Notice: The manufacturer reserves the right to make any changes and improvements
to the products described in this manual at any time and without notice. This manual
is copyrighted. This document may not, in whole or in part, be copied, reproduced,
translated, or converted to any electronic medium or machine readable form, for
commercial purposes, without prior written consent from the copyright holder.
Note: Although we provide assistance on our products both personally and through
our literature, it is the complete responsibility of the user to determine the suitability
of any product to their application.
The manufacturer does not warrant or assume responsibility for the use of its
products in life support applications or systems.
Wide-Range Laminar Flow Element Patent:
The wide-range laminar ow element and products using the wide-range laminar
ow element are covered by U.S. Patent Number: 5,511,416. Manufacture or use of
the wide-range laminar ow element in products other than products licensed under
said patent will be deemed an infringement.
Warranty
This product is warranted to the original purchaser for a period of one year from the date
of purchase to be free of defects in material or workmanship. Under this warranty the
product will be repaired or replaced at manufacturer’s option, without charge for parts or
labor when the product is carried or shipped prepaid to the factory together with proof of
purchase. This warranty does not apply to cosmetic items, nor to products that are damaged,
defaced or otherwise misused or subjected to abnormal use. See “Application” under the
Installation section. Where consistent with state law, the manufacturer shall not be liable
for consequential economic, property, or personal injury damages. The manufacturer does
not warrant or assume responsibility for the use of its products in life support applications
or systems.
10/24/06 Rev. 0 DOC-APEXMAN16C
Table of ContentsPage
Installation5
Plumbing5
Mounting5
Application5
Power and Signal Connections6
Input Signals7
Analog Input Signal7
RS-232 Input Signal7
Output Signals7
RS-232 Digital Output Signal8
Standard Voltage (0-5 Vdc) Output Signal8
Optional 0-10 Vdc Output Signal8
Optional Current (4-20 mA) Output Signal8
Optional 2nd Analog Output Signal8
MC Series Mass Flow Controller Operation10
Main Mode10
Set Pt.10
Gas Absolute Pressure10
Gas Temperature11
Volumetric Flow Rate11
Mass Flow Rate11
Flashing Error Message11
Select Menu Mode11
Control Setup Mode12
Input12
Loop13
Select13
Gas Select Mode14
Communication Select Mode15
Unit ID15
Baud15
Data Rate15
Manufacturer Data Mode16
VC Series Volumetric Flow Controller Operation17
Main Mode17
Volume17
Set Pt.17
Flashing Error Message17
Select Menu Mode18
Control Setup Mode18
Input18
Select18
Gas Select Mode20
Communication Select Mode20
Table of ContentsPage
Manufacturer Data Mode20
RS-232 Output and Input20
Conguring HyperTerminal®20
Changing from Streaming to Polling Mode 20
Sending a Set-Point via RS-23221
To adjust the P & D terms via RS-23221
Gas Select 23
Collecting Data24
Data Format 24
Sending a Simple Script File to HyperTerminal®25
Operating Principle26
Gas Viscosity26
Other Gases27
Volume Flow vs. Mass Flow27
Volumetric Flow and Mass Flow Conversion28
Compressibility28
Standard Gas Data Tables29
Gas Viscosities and Densities Table30
Volumetric Flow Meters Under Pressure31
Troubleshooting32
Maintenance and Recalibration33
Technical Specications34
Dimensional Drawings38
Figure 1. 8 Pin Mini-DIN Connector 6
Figure 2. Simple method for providing set-point to controllers7
Figure 3. Mini-DIN to DB-9 Connection for RS-232 Signals8
Figure 4. Typical Multiple Device (Addressable) Wiring Conguration 9
Figure 5. Optional Industrial Connector9
Figure 6. Main Mode Display, MC Series Flow Controller10
Figure 7. Select Menu Display11
Figure 8. MC Series Control Setup Display12
Figure 9. Gas Select Display14
Figure 10. Communication Select Display15
Figure 11. Manufacturer Data Displays16
Figure 12. Main Mode Display, VC Series Flow Controller17
Figure 13. VC Series Control Setup Display18
Thank you for purchasing an Apex MC or VC Series Gas Flow Controller. Please take the time to nd
and read the information contained in this manual. This will help to ensure that you get the best possible
service from your instrument. This manual covers the following Apex instruments:
MC Series 16 Bit Mass Gas Flow Controllers
VC Series 16 Bit Volumetric Gas Flow Controllers
Installation
Plumbing
All MC and VC Series Gas Flow Controllers are equipped with female inlet and outlet port connections.
Because the ow meters set up a laminar ow condition within the ow body, no straight runs of pipe
are required upstream or downstream of the controller. The inlet and outlet ports are equal in size and
symmetric (in-line). The port sizes (process connections) and mechanical dimensions for different ow
ranges are shown on pages 34-37.
Controllers with 10-32 ports have o-ring face seals and require no further sealant or tape. On other
controllers, avoid the use of pipe dopes or sealants on the ports as these compounds can cause
permanent damage to the controller should they get into the ow stream. Use of thread sealing Teon
tape is recommended to prevent leakage around the threads. When applying the tape, avoid wrapping
the rst thread or two to minimize the possibility of getting a piece of shredded tape into the ow stream.
When changing ttings, always clean any tape or debris from the port threads.
It is also recommended that a 20 micron lter be installed upstream of controllers with full scale ranges
of 1(S)LPM or less and a 50 micron lter be installed upstream of controllers with full scale ranges
above 1(S)LPM.
Mounting
All MC and VC Series Gas Flow Controllers have mounting holes for convenient mounting to at panels.
The sizes and dimensions for the mounting holes are shown on pages 38-40. Position sensitivity is not
generally an issue with small valve controllers. Large valve controllers are somewhat position sensitive
because of the fairly massive stem assembly. It is generally recommended that they be mounted so
that the valve cylinder is vertical and upright. The primary concern in mounting a large valve controller
in a position other than the recommended position is the increased risk of leakage when the controller
is given a zero set-point and is being held closed by the spring force.
Application
Maximum operating line pressure is 125 PSIG (862 kPa).
Caution: Exceeding the maximum specied line pressure may cause permanent damage to the
solid-state differential pressure transducer.
If the line pressure is higher than 125 PSIG (862 kPa), a pressure regulator should be used upstream
from the ow meter to reduce the pressure to 125 PSIG (862 kPa) or less if possible. Many of our
controllers are built after extensive consultations with the customer regarding the specic application.
The result is that two controllers with the same ow range and part number may look and act quite
differently depending upon the application the controller was built for. Care should be taken in moving a
controller from one application to another to test for suitability in the new application. Note that volumetric
meters and controllers are not recommended for high pressure or high backpressure applications (see
page 31).
5
Power and Signal Connections
78
1
2
345
AC/DC Adapter Jack
6
Power can be supplied to your MC or VC Series controller through either the power jack or the 8 pin
Mini-DIN connector as shown in Figure 1. An AC to DC adapter which converts line AC power to DC
voltage and current as specied below. The power jack accepts 2.1 mm female power plugs with positive
centers. Cables and AC/DC adaptors may purchased from the manufacturer (see Accessories page 43)
and are commonly available at local electronics suppliers. Alternatively, power can be supplied through
the Mini-DIN connector as shown below:
Small Valve: If your controller utilizes a small valve (about the size of your thumb), a 12-18
Vdc (standard 68ohm valve coil) or 19-28 Vdc (optional 136ohm valve coil) power supply with a 2.1
mm female positive center plug capable of supplying 300 mA is recommended. Note: 4-20mA output
requires at least 15 Vdc.
Large Valve: If your controller utilizes a large valve (about the size of your st), a 24-30 Vdc power
supply with a 2.1 mm female positive center plug capable of supplying at least 750mA is required.
7Power In (as described above)Blue
8Ground (common for power, communications and signals)Purple
Note: The above pin-out is applicable to all the ow meters and controllers available with the MiniDIN connector. The availability of different output signals depends on the ow meter options ordered.
UnderlinedItems in the above table are optional congurations that are noted on the unit’s
calibration sheet.
Static 5.12 Vdc or Secondary Analog Output (4-20mA, 5Vdc, 10Vdc) or
Basic Alarm
2
45
7
8
Mini-DIN
cable color
Brown
Figure 1. 8 Pin Mini-DIN Connector
CAUTION: Do not connect power to pins 1 through 6 as permanent damage can occur!
Note: Upon initial review of the pin out diagram in Figure 1, it is common to mistake Pin 2 (labeled
5.12 Vdc Output) as the standard 0-5 Vdc analog output signal! In fact Pin 2 is normally a constant
5.12 Vdc that reects the system bus voltage and can be used as a source for the set-point signal.
6
Input Signals
7
6
5
4
3
2
1
8
5.12 Vdc
50 KOhm
Potentiometer
0-5 Vdc
Analog Input Signal
Apply analog input to Pin 4 as shown in Figure 1.
Standard 0-5 Vdc: Unless ordered otherwise, 0-5 Vdc is the standard analog input signal. Apply the
0-5 Vdc input signal to pin 4, with common ground on pin 8. The 5.12 Vdc output on pin 2 can be wired
through a 50K ohm potentiometer and back to the analog input on pin 4 to create an adjustable 0-5 Vdc
input signal source as shown below.
Figure 2. Simple method for providing set-point to controllers
Optional 0-10 Vdc: If specied at time of order, a 0-10 Vdc input signal can be applied to pin 4, with
common ground on pin 8.
Optional 4-20 mA: If specied at time of order, a 4-20 mA input signal can be applied to pin 4, with
common ground on pin 8. Note: 4-20mA output requires at least 15 Vdc power input.
RS-232 Digital Input Signal
If you will be using the RS-232 input signal, it is necessary to connect the RS-232 Output Signal (Pin
5), the RS-232 Input Signal (Pin 3), and Ground (Pin 8) to your computer serial port as shown in Figure
3. Adapter cables are available from the manufacturer or they can be constructed in the eld with parts
from an electronics supply house. In Figure 3, note that the diagrams represent the “port” side of the
connections, i.e. the connector on top of the meter and the physical DB-9 serial port on the back of the
computer. The cable ends will be mirror images of the diagram shown in Figure 3. (See page 20 for
details on accessing RS-232 input.)
Output Signals
Note: Upon initial review of the pin out diagram in Figure 1 (page 6), it is common to mistake Pin 2
(labeled 5.12 Vdc Output) as the standard 0-5 Vdc analog output signal! In fact Pin 2 is normally a
constant 5.12 Vdc that reects the system bus voltage and can be used as a source for the input signal.
This allows the user in the eld to run this output through a 50K ohm potentiometer and back into the
analog set-point pin to create a 0-5 Vdc set-point source.
RS-232 Digital Output Signal
If you will be using the RS-232 output signal, it is necessary to connect the RS-232 Output Signal (Pin
5), the RS-232 Input Signal (Pin 3), and Ground (Pin 8) to your computer serial port as shown in Figure
3. Adapter cables are available from the manufacturer or they can be constructed in the eld with parts
from an electronics supply house. In Figure 3, note that the diagrams represent the “port” side of the
7
connections, i.e. the connector on top of the meter and the physical DB-9 serial port on the back of the
computer. The cable ends will be mirror images of the diagram shown in Figure 3. (See page 20 for
details on accessing RS-232 output.)
Standard Voltage (0-5 Vdc) Output Signal
All MC and VC Series ow controllers have a 0-5 Vdc (optional 0-10 Vdc) output signal available on
Pin 6. This is generally available in addition to other optionally ordered outputs. This voltage is usually
in the range of 0.010 Vdc for zero ow and 5.0 Vdc for full-scale ow. The output voltage is linear over
the entire range. Ground for this signal is common on Pin 8.
Optional 0-10 Vdc Output Signal
If your controller was ordered with a 0-10 Vdc output signal, it will be available on Pin 6. (See the
Calibration Data Sheet that shipped with your controller to determine which output signals were
ordered.) This voltage is usually in the range of 0.010 Vdc for zero ow and 10.0 Vdc for full-scale ow.
The output voltage is linear over the entire range. Ground for this signal is common on Pin 8.
Optional Current (4-20 mA) Output Signal
If your controller was ordered with a 4-20 mA current output signal, it will be available on Pin 1. (See
the Calibration Data Sheet that shipped with your controller to determine which output signals were
ordered.) The current signal is 4 mA at 0 ow and 20 mA at the controller’s full scale ow. The output
current is linear over the entire range. Ground for this signal is common on Pin 8. (Current output units
require 15-30Vdc power.)
Note: This is a current sourcing device. Do not attempt to connect it to “loop powered” systems.
Optional 2nd Analog Output Signal
You may specify an optional 2nd analog output on Pin 2 at time of order. (See the Calibration Data
Sheet that shipped with your controller to determine which output signals were ordered.) This output
may be a 0-5 Vdc, 0-10 Vdc, or 4-20 mA analog signal that can represent any measured parameter.
With this optional output, a volumetric ow controller could output the volumetric ow rate with a 0-5
Vdc signal (on pin 6) and a 4-20 mA signal (on pin 2), or a mass ow controller could output the mass
ow rate (0-5 Vdc on pin 6) and the absolute pressure (0-5 Vdc on pin 2).
Note: This is a current sourcing device. Do not attempt to connect it to “loop powered” systems.
2
4
6
7
5
8
Figure 3. Mini-DIN to DB-9 Connection for RS-232 Signals
Note: The above pin-out is applicable to all the ow meters and controllers ordered with the industrial
connector. The availability of different output signals depends on the ow controller options ordered.
9
MC Series Mass Flow Controller Operation
The MC Series Mass Flow Controller provides a multitude of useful ow data in one simple, rugged
device. The MC Series can have several screen “modes” depending on how the device is ordered.
All MC Series controllers have a default Main Mode, Select Menu Mode, Control Set Up Mode, Gas
Select Mode (the Gas Select Mode may not be available on controllers calibrated for a custom gas or
blend), Communication Select Mode and Manufacturer Data Mode. (In addition, your device may have
been ordered with a Totaliizing Mode, page 41.) The device defaults to Main Mode as soon as power
is applied to the controller.
Main Mode
The main mode screen defaults on power up with the mass ow on the primary display. The following
parameters are displayed in the main mode as shown in Figure 6.
PSIA oC Set Pt.
+13.49 +22.73 0.000
SCCM
Air
+0.000 +0.000
Volume Mass Main
MASS
Figure 6. Main Mode Display, MC Series Flow Controller
The “MODE” button in the lower right hand corner toggles the display between modes.
Set Pt. – The set-point is shown in the upper right corner of the display. The set-point cannot be adjusted
from the main mode screen. For information on changing the set-point, see “Set”, page 13.
Gas Absolute Pressure: The MC Series ow controllers utilize an absolute pressure sensor to measure
the line pressure of the gas ow being monitored. This sensor references hard vacuum and accurately
reads line pressure both above and below local atmospheric pressure. This parameter is located in
the upper left corner of the display under the dynamic label “PSIA”. This parameter can be moved to
the primary display by pushing the button just above the dynamic label (top left). The engineering unit
associated with absolute pressure is pounds per square inch absolute (PSIA). This can be converted
to gage pressure (PSIG = the reading obtained by a pressure gauge that reads zero at atmospheric
pressure) by simply subtracting local atmospheric pressure from the absolute pressure reading:
PSIG = PSIA – (Local Atmospheric Pressure)
The ow meters use the absolute pressure of the gas in the calculation of the mass ow rate. For
working in metric units, note that 1 PSI = 6.89 kPa.
10
Gas Temperature: The MC Series ow controllers utilize a temperature sensor to measure the line
temperature of the gas ow being monitored. The temperature is displayed in engineering units of
degrees Celsius (°C). The ow controllers use the temperature of the gas in the calculation of the mass
ow rate. This parameter is located in the upper middle portion of the display under “°C”. This parameter
can be moved to the primary display by pushing the top center button above “°C”.
Volumetric Flow Rate: The volumetric ow rate is determined using the Flow Measurement Operating
Principle described on page 26. This parameter is located in the lower left corner of the display over
“Volume”. This parameter can be moved to the primary display by pushing the “Volume” button (lower
left). In order to get an accurate volumetric ow rate, the gas being measured must be selected (see
Gas Select Mode). This is important because the device calculates the ow rate based on the viscosity
of the gas at the measured temperature. If the gas being measured is not what is selected, an incorrect
value for the viscosity of the gas will be used in the calculation of ow, and the resulting output will be
inaccurate in direct proportion to the ratio between the two gases viscosities.
Mass Flow Rate: The mass ow rate is the volumetric ow rate corrected to a standard temperature
and pressure (typically 14.696 psia and 25°C). This parameter is located in the lower middle portion
of the display over “Mass”. This parameter can be moved to the primary display by pushing the button
located below “Mass” (bottom center). The controllers uses the measured temperature and the measured
absolute pressure to calculate what the ow rate would be if the gas pressure was at 1 atmosphere and
the gas temperature was 25°C. This allows a solid reference point for comparing one ow to another.
Flashing Error Message: Our ow meters and controllers display an error message (MOV = mass
overrange, VOV = volumetric overrange, POV = pressure overrange, TOV = temperature overrange)
when a measured parameter exceeds the range of the sensors in the device. When any item ashes
on the display, neither the ashing parameter nor the mass ow measurement is accurate. Reducing
the value of the ashing parameter to within specied limits will return the unit to normal operation and
accuracy.
Select Menu Mode
Pushing “Mode” once will bring up the “Select Menu” display. Push the button nearest your selection
to go to the corresponding screen. Push “Mode” again to return to the Main Mode display. (Note: If
your controller was ordered with Totalizing Mode option (page 41), pushing the “Mode” button once will
bring up the “Totalizing Mode” display. Pushing “Mode” a second time will bring up the “Select Menu”
display.)
Gas Control
Select
SELECT
MENU
Comm. Mfg.
RS-232 Data Menu
Figure 7. Select Menu Display
11
Control Setup Mode
The Control Setup Mode is accessed by pressing the center button above “Control” on the Select Menu
display (Fig.7) This mode allows the user to set up most parameters commonly associated with PID
control. MC Series ow controllers allow the user to select how the set-point is to be conveyed to the
controller, what that set-point is if control is local, and what the Proportional and Differential terms of the
PID control loop will be. The UP and DOWN buttons for adjusting variables can be held down for higher
speed adjustment or pressed repeatedly for ne adjustment.
Input – MC Series Flow Controllers normally ship defaulted to analog control as indicated in Figure 8.
To change how the set-point will be conveyed to the controller push the button in the upper right hand
corner just above the dynamic label “Input” until the arrow is directly in front of the desired option. The
controller will ignore any set-point except that of the selected input and it will remember which input is
selected even if the power is disconnected.
Analog refers to a remote analog set-point applied to Pin 4 of the Mini-DIN connector as described
in the installation section of this manual. To determine what type of analog set-point your controller
was ordered with, refer to the Calibration Data Sheet that was included with your controller. 0-5 Vdc is
standard unless ordered otherwise. Note that if nothing is connected to Pin 4, and the controller is set
for analog control, the set-point will oat. CAUTION! Neverleavea CoNtrollerwithaNyNoN-zeroset-
Serial refers to a remote digital RS-232 set-point applied via a serial connection to a computer or
PLC as described in the Installation and RS-232 sections of this manual. CAUTION! Neverleavea
Loop—The selection of what variable to close the loop on is a feature unique to these mass ow
controllers. When the mass ow controller is supplied with the control valve upstream of the electronics
portion of the system, the unit can be set to control on outlet pressure (absolute pressures only) or
volumetric ow rate, instead of mass ow rate. Repeatedly pressing the button adjacent to the word
“Loop” on the control setup screen will change what variable is controlled. The change from mass to
volume can usually be accomplished without much, if any, change in the P and D settings. When you
change from controlling ow to controlling pressure, sometimes fairly radical changes must be made
to these variables. Note: Full scale pressure is normally 160PSIA. Consult the factory if you are having
difculties with this procedure.
Select – To avoid accidental changing of the PID loop parameters or the set-point, the Control Setup
mode defaults with the selector on a null position. To change the set-point or the P and D PID loop
parameters, push the button in the upper left corner just above the dynamic label “Select” until the
selection arrow is pointing to the parameter you wish to change. When the parameter you wish to
change is selected, it may be adjusted up or down with the buttons under the display below the dynamic
labels “Up” and “Down”. Press the buttons repeatedly to make slow adjustments or hold them down to
make fast adjustments.
P refers to the Proportional term of the PID loop. Before changing this parameter, it is good practice to
write down the initial value so that it can be returned to the factory settings if necessary.
D refers to the Differential term of the PID loop. Before changing this parameter, it is good practice to
write down the initial value so that it can be returned to the factory settings if necessary.
AUT0on / AUT0off refers to the standard auto-tare or “auto-zero” feature. It is recommended that the
controller be left in the default auto-tare ON mode unless your specic application requires that it be
turned off. The auto-tare feature automatically tares (takes the detected signal as zero) the unit when it
receives a zero set-point for more than two seconds. A zero set-point results in the closing of the valve
and a known “no ow” condition. This feature helps to make the device more accurate by periodically
removing any cumulative errors associated with drift.
Set refers to the Set-Point. This parameter may only be changed if “Local” is selected as the Input. See
above for information on selecting the input. Using the UP and DOWN buttons, the set-point may be
adjusted between zero and the full-scale range of the controller. CAUTION! Neverleavea CoNtroller
withaNyNoN-zeroset-poiNtifNopressureisavailabletomakeflow. theCoNtrollerwillapplyfull
powertothevalveiNaNattempttoreaChtheset-poiNt. wheNthereisNoflow, thisCaNmakethevalve
very hot!
13
Gas Select Mode
The gas select mode is accessed by pressing the button above “Gas Select” on the Select Menu
display. The screen will appear as shown in Figure 9.
PgUP PgDWN Main
H2 Hydrogen
He Helium
>N2 Nitrogen
N2O Nitrous Oxide
Ne Neon
O2 Oxygen
UP DOWN Gas
Figure 9. Gas Select Mode
The selected gas is displayed on the default main mode screen as shown in Figure 6, and is indicated
by the arrow in the Gas Select Mode screen in Figure 9. To change the selected gas, use the buttons
under “UP” and “DOWN” or above “PgUP” and “PgDWN” to position the arrow in front of the desired
gas. When the mode is cycled back to the Main Mode, the selected gas will be displayed on the main
screen. (Note: Gas Select Mode may not be available for units ordered for use with a custom gas or
blend.)
14
Communication Select Mode
The Communication Select mode is accessed by pressing the button below “Comm. RS-232” on the
Select Menu display. The screen will appear as shown in Figure 10.
Select Main
>
Unit ID (A).....A
Baud (19200)....19200
Data Rate......Fast
Comm.
UP DOWN RS-232
Figure 10. Communication Select Display
Unit ID – Valid unit identiers are letters A-Z and @ (see Note below). This identier allows the user
to assign a unique address to each device so that multiple units can be connected to a single RS-232
port on a computer. The Communication Select Mode allows you to view and/or change a unit’s unique
address. To change the unit ID address, press the “Select” button in the upper left corner of the display
until the cursor arrow is in front of the word “Unit ID”. Then, using the UP and DOWN buttons at the
bottom of the display, change the unit ID to the desired letter. Any ID change will take effect when the
Communication Select Screen is exited by pushing the MODE button.
Note: When the symbol @ is selected as the unit ID, the device will go into streaming mode when the
Communication Select Mode is exited by pushing the MODE button. See RS-232 Communications
(page 18) for information about the streaming mode.
Baud – The baud rate (bits per second) determines the rate at which data is passed back and forth
between the instrument and the computer. Both devices must send/receive at the same baud rate in
order for the devices to communicate via RS-232. The default baud rate for these devices is 19200
baud, sometimes referred to as 19.2K baud. To change the baud rate in the Communication Select
Mode, press the “Select” button in the upper left corner of the display until the cursor arrow is in front
of the word “Baud”. Then, using the UP and DOWN buttons at the bottom of the display, select the
required baud rate to match your computer or PLC. The choices are 38400, 19200, 9600, or 2400 baud.
Any baud rate change will not take effect until power to the unit is cycled.
Data Rate – Changing the Data Rate affects the rate at which the instrument dumps its data in the
streaming mode. Slow is ½ the Fast rate. The speed of the Fast rate is determined by the selected
baud rate. It is sometimes desirable to reduce the data rate if the communication speed bogs down
the computer’s processor (as is not uncommon in older laptops), or to reduce the size of data les
collected in the streaming mode. To change the data rate in the Communication Select Mode, press the
“Select” button in the upper left corner of the display until the cursor arrow is in front of the word “Data
Rate”. Then, using the UP and DOWN buttons at the bottom of the display, select either Fast or Slow.
Any data rate change will be effective immediately upon changing the value between Fast and
Slow.
15
Manufacturer Data Mode
“Manufacturer Data” is accessed by pressing the “Mfg. Data” button on the Select Menu display (Figure
11). The “Mfg 1” display shows the name and telephone number of the manufacturer. The“Mfg 2”
display shows important information about your ow meter including the model number, serial number,
and date of manufacture.
Main
Apex
Ph 404-474-3115
Mfg 1
Main
Model MC-10SLPM-D
Serial No 27117
Date Mfg.11/07/2005
Calibrated By.DL
Software GP07R23
Mfg 2
Figure 11. Manufacturer Data Displays
16
VC Series Volumetric Flow Controller Operation
The VC Series can have several screen “modes” depending on how the device is ordered. All VC Series
controllers have a default Main Mode, Select Menu Mode, Control Setup Mode, Gas Select Mode (the
Gas Select Mode may not be available on meters calibrated for a custom gas or blend), Communication
Select Mode and Manufacturer Data Mode. (In addition, your device may have been ordered with
a Totaliizing Mode, page 41.) The device defaults to Main Mode as soon as power is applied to the
controller. Note that volumetric controllers are intended for use in near atmospheric conditions (Please
see page 31).
Main Mode
The main mode screen shows the volumetric ow in the units specied at time of order. In the ow
mode, only two buttons are active as shown in Figure 12. The process gas that is selected is shown
directly under the ow units.
Set Pt.
0.000
Volume
CCM
Air
+0.000
Volume Main
Figure 12. Main Mode Display, VC Series Flow Controller
The “MODE” button in the lower right hand corner toggles the display between the Main Display and
the Menu Display.
Volume – The volume ow rate is defaulted on the primary display. If the set-point has been toggled to
the primary screen as described below, the volume ow rate can be toggled back to the primary display
by pushing the button (lower left corner) directly beneath the dynamic label “Volume”.
Set Pt – The set-point is shown in the upper right corner of the display. The set-point cannot be adjusted
from the main mode screen. For information on changing the set-point, see “Control Setup Mode”.
Flashing Error Message: Our volumetric ow meters and controllers display an error message (VOV
= volumetric overrange) when a measured parameter exceeds the range of the sensors in the device.
When any item ashes on the display, the ashing parameter is not accurate. Reducing the value of the
ashing parameter to within specied limits will return the unit to normal operation and accuracy.
17
Select Menu Mode
Pushing “Mode” once will bring up the “Select Menu” display (Figure 7, page 11). Push the button
nearest your selection to go to the corresponding screen. Push “Mode” again to return to the Main
Mode display. (Note: If your controller was ordered with Totalizing Mode option (page 41), pushing
the “Mode” button once will bring up the “Totalizing Mode” display. Pushing “Mode” a second time will
bring up the “Select Menu” display.)
Control Setup Mode
The Control Setup Mode is accessed by pressing the center button above “Control” on the Select Menu
Display (Fig.7 page 11) This mode allows the user to set up most parameters commonly associated
with PID control. VC Series ow controllers allow the user to select how the set-point is to be conveyed
to the controller, what that set-point is if control is local, and what the Proportional and Differential terms
of the PID control loop will be. The UP and DOWN buttons for adjusting variables can be held down for
higher speed adjustment or pressed repeatedly for ne adjustment
Select Loop Input
>P 200 >Analog
D 500 Volume Serial
AUT0on
Set 0.00
Up Down Setup
Local
Control
Figure 13. VC Series Control Setup Display
Input – VC Series Flow Controllers normally ship defaulted to analog control as indicated in Figure 13
above. To change how the set-point will be conveyed to the controller push the button in the upper right
hand corner just above the dynamic label “Input” until the arrow is directly in front of the desired option.
The controller will ignore any set-point except that of the selected input and it will remember which input
is selected even if the power is disconnected.
Analog refers to a remote analog set-point applied to Pin 4 of the Mini-DIN connector as described
in the installation section of this manual. To determine what type of analog set-point your controller
was ordered with, refer to the Calibration Data Sheet that was included with your controller. 0-5 Vdc is
standard unless ordered otherwise. Note that if nothing is connected to Pin 4, and the controller is set
for analog control, the set-point will oat. CAUTION! Neverleavea CoNtrollerwithaNyNoN-zeroset-
Serial refers to a remote digital RS-232 set-point applied via a serial connection to a computer or
PLC as described in the Installation and RS-232 sections of this manual. CAUTION! Neverleavea
Select – To avoid accidental changing of the PID loop parameters or the set-point, the Control Setup
mode defaults with the selector on a null position. To change the set-point or the P and D PID loop
parameters, push the button in the upper left corner just above the dynamic label “Select” until the
selection arrow is pointing to the parameter you wish to change. When the parameter you wish to
change is selected, it may be adjusted up or down with the buttons under the display below the dynamic
labels “UP” and “DOWN”. Press the buttons repeatedly to make slow adjustments or hold them down
to make fast adjustments.
P refers to the Proportional term of the PID loop. Before changing this parameter, it is good practice to
write down the initial value so that it can be returned to the factory settings if necessary.
D refers to the Differential term of the PID loop. Before changing this parameter, it is good practice to
write down the initial value so that it can be returned to the factory settings if necessary.
AUT0on / AUT0off refers to the standard auto-tare or “auto-zero” feature. It is recommended that the
controller be left in the default auto-tare ON mode unless your specic application requires that it be
turned off. The auto-tare feature automatically tares (takes the detected signal as zero) the unit when it
receives a zero set-point for more than two seconds. A zero set-point results in the closing of the valve
and a known “no ow” condition. This feature helps to make the device more accurate by periodically
removing any cumulative errors associated with drift.
Set refers to the Set-point. This parameter may only be changed if “Local” is selected as the Input. See
above for information on selecting the input. Using the UP and DOWN buttons, the set-point may be
adjusted between zero and the full-scale range of the controller. CAUTION! Neverleavea CoNtroller
withaNyNoN-zeroset-poiNtifNopressureisavailabletomakeflow. theCoNtrollerwillapplyfull
powertothevalveiNaNattempttoreaChtheset-poiNt. wheNthereisNoflow, thisCaNmakethevalve
very hot!
19
Gas Select Mode
The Gas Select Mode is accessed by pressing the button above “Gas Select” on the Select Menu
display. The screen will appear as shown in Figure 9 (page 13). The selected gas is displayed on the
default main mode screen as shown in Figure 11, and is indicated by the arrow in the gas select mode
screen in Figure 9. To change the selected gas, use the buttons under “UP” and “DOWN” or those
above “PgUP” and “PgDWN” to position the arrow in front of the desired gas. When the mode is cycled
back to the main mode, the selected gas will be displayed on the main screen.
Note: Gas Select Mode may not be available for units ordered for use with a custom gas or blend.
Communication Select Mode
The Communication Select mode is accessed by pressing the button below “Comm. RS-232” on the
Select Menu display. Please see page 14 for Communication Select mode instructions.
Manufacturer Data Mode
“Manufacturuer Data” is accessed by pressing the “Mfg. Data” button on the Select Menu display
(Figure 7, page 11). The “Mfg 1” display shows the name and telephone number of the manufacturer.
The“Mfg 2” display shows important information about your ow controller including the model number,
serial number, and date of manufacture (Figure 10, page 14).
RS-232 Output and Input
Conguring HyperTerminal®:
Open your HyperTerminal® RS-232 terminal program (installed under the “Accessories” menu on
1.
all Microsoft Windows operating systems).
Select “Properties” from the le menu.
2.
Click on the “Congure” button under the “Connect To” tab. Be sure the program is set for: 19,200
3.
baud (or matches the baud rate selected in the RS-232 communications menu on the controller)
and an 8-N-1-None (8 Data Bits, No Parity, 1 Stop Bit, and no Flow Control) protocol.
Under the “Settings” tab, make sure the Terminal Emulation is set to ANSI or Auto Detect.
4.
Click on the “ASCII Setup” button and be sure the “Send Line Ends with Line Feeds” box is not
5.
checked and the “Echo Typed Characters Locally” box and the “Append Line Feeds to Incoming
Lines” boxes are checked. Those settings not mentioned here are normally okay in the default
position.
Save the settings, close HyperTerminal® and reopen it.
6.
In Polling Mode, the screen should be blank except the blinking cursor. In order to get the data streaming
to the screen, hit the “Enter” key several times to clear any extraneous information. Type “*@=@”
followed by “Enter” (or using the RS-232 communcation select menu, select @ as identier and exit the
screen). If data still does not appear, check all the connections and com port assignments.
Changing From Streaming to Polling Mode:
When the meter is in the Streaming Mode, the screen is updated approximately 10-60 times per second
(depending on the amount of data on each line) so that the user sees the data essentially in real time.
It is sometimes desirable, and necessary when using more than one unit on a single RS-232 line, to be
able to poll the unit.
20
In Polling Mode the unit measures the ow normally, but only sends a line of data when it is “polled”.
Each unit can be given its own unique identier or address. Unless otherwise specied each unit is
shipped with a default address of capital A. Other valid addresses are B thru Z.
Once you have established communication with the unit and have a stream of information lling your
screen:
Type *@=A followed by “Enter” (or using the RS-232 communcation select menu, select A as identier
1.
and exit the screen) to stop the streaming mode of information. Note that the ow of information will
not stop while you are typing and you will not be able to read what you have typed. Also, the unit
does not accept a backspace or delete in the line so it must be typed correctly. If in doubt, simply hit
enter and start again. If the unit does not get exactly what it is expecting, it will ignore it. If the line
has been typed correctly, the data will stop.
You may now poll the unit by typing A followed by “Enter”. This does an instantaneous poll of unit
2.
A and returns the values once. You may type A “Enter” as many times as you like. Alternately you
could resume streaming mode by typing *@=@ followed by “Enter”. Repeat step 1 to remove the
unit from the streaming mode.
To assign the unit a new address, type *@=New Address, e.g. *@=B. Care should be taken not to
3.
assign an address to a unit if more than one unit is on the RS232 line as all of the addresses will be
reassigned. Instead, each should be individually attached to the RS-232 line, given an address, and
taken off. After each unit has been given a unique address, they can all be put back on the same
line and polled individually.
Sending a Set-point via RS-232: To send a set-point via RS-232, “Serial” must be selected under
the “Input” list in the control set up mode. To give controllers a set-point, or change an existing point,
simply type in a number between 0 and 65535 (2% over range), where 64000 denotes full-scale ow
rate, and hit “Enter”. The set-point column and ow rates should change accordingly. If they do not,
try hitting “Enter” a couple of times and repeating your command. The formula for performing a linear
interpolation is as follows:
Value = (Desired Set-point X 64000) / Full Scale Flow Range
For example, if your device is a 100 SLPM full-scale unit and you wish to apply a set-point of 35 SLPM
you would enter the following value:
22400 = (35 SLPM X 64000) / 100 SLPM
If the controller is in polling mode as described in Changing from Streaming Mode to Polling Mode, the
set-point must be preceded by the address of the controller. For example, if your controller has been
given an address of D, the set-point above would be sent by typing:
D22400 followed by “Enter”
To adjust the Proportional and Differential (P&D) terms via RS-232:
Type *@=A followed by “Enter” to stop the streaming mode of information.
To adjust the “P” or proportional term of the PID controller, type *R21 followed by “Enter”.
21
The computer will respond by reading the current value for register 21 between 0-65535. It is good
practice to write this value down so you can return to the factory settings if necessary. Enter the value
you wish to try by writing the new value to register 21. For example, if you wished to try a “P” term of
220, you would type *W21=220 followed by “Enter” where the bold number denotes the new value.
The computer will respond to the new value by conrming that 21=220. To see the effect of the change
you may now poll the unit by typing A followed by “Enter”. This does an instantaneous poll and returns
the values once. You may type A “Enter” as many times as you like. Alternately you could resume
streaming mode by typing *@=@ followed by “Enter”. Repeat step 3 to remove the unit from the
streaming mode.
To adjust the “D” or proportional term of the PID controller, type *R22 followed by “Enter”.
The computer will respond by reading the current value for register 22 between 0-65535. It is good
practice to write this value down so you can return to the factory settings if necessary. Enter the value
you wish to try by writing the new value to register 22. For example, if you wished to try a “D” term of
25, you would type *W22=25 followed by “Enter” where the bold number denotes the new value.
The computer will respond to the new value by conrming that 22=25. To see the effect of the change
you may now poll the unit by typing A followed by “Enter”. This does an instantaneous poll and returns
the values once. You may type A “Enter” as many times as you like. Alternately you could resume
streaming mode by typing *@=@ followed by “Enter”. Repeat.
You may test your settings for a step change by changing the set-point. To do this type A32000 (A is the
default single unit address, if you have multiple addressed units on your RS-232 line the letter preceding
the value would change accordingly.) followed by “Enter” to give the unit a ½ full scale setpoint. Monitor
the unit’s response to the step change to ensure it is satisfactory for your needs. Recall that the “P” term
controls how quickly the unit goes from one setpoint to the next, and the “D” term controls how quickly
the signal begins to “decelerate” as it approaches the new set-point (controls the overshoot).
22
Gas Select – The selected gas can be changed via RS-232 input. To change the selected gas, enter
the following commands:
In Streaming Mode: $$#<Enter>
In Polling Mode: Address$$#<Enter> (e.g. B$$#<Enter>)
Where # is the number of the gas selected from the table below. Note that this also corresponds to the
gas select menu on the ow controller screen:
#GAS
0AirAir
1Argon Ar
2Methane CH4
3Carbon Monoxide CO
4Carbon Dioxide CO2
5Ethane C2H6
6Hydrogen H2
7Helium He
8Nitrogen N2
For example, to select Propane, enter: $$12<Enter>
23
Collecting Data:
The RS-232 output updates to the screen many times per second. Very short-term events can be
captured simply by disconnecting (there are two telephone symbol icons at the top of the HyperTerminal®
screen for disconnecting and connecting) immediately after the event in question. The scroll bar can be
driven up to the event and all of the data associated with the event can be selected, copied, and pasted
into Microsoft® Excel® or other spreadsheet program as described below.
For longer term data, it is useful to capture the data in a text le. With the desired data streaming to the
screen, select “Capture Text” from the Transfer Menu. Type in the path and le name you wish to use.
Push the start button. When the data collection period is complete, simply select “Capture Text” from
the Transfer Menu and select “Stop” from the sub-menu that appears.
Data that is selected and copied, either directly from HyperTerminal® or from a text le can be pasted
directly into Excel®. When the data is pasted it will all be in the selected column. Select “Text to
Columns...” under the Data menu in Excel® and a Text to Columns Wizard (dialog box) will appear.
Make sure that “Fixed Width” is selected under Original Data Type in the rst dialog box and click “Next”.
In the second dialog box, set the column widths as desired, but the default is usually acceptable. Click
on “Next” again. In the third dialog box, make sure the column data format is set to “General”, and click
“Finish”. This separates the data into columns for manipulation and removes symbols such as the plus
signs from the numbers. Once the data is in this format, it can be graphed or manipulated as desired.
For extended term data capture see: “Sending a Simple Script to HyperTerminal®” on page 25.
Data Format:
The data stream on the screen represents the ow parameters of the main mode in the units shown
on the display. For volumetric ow controllers, there are three columns of data representing volumetric
ow rate in the units specied at time of order, set point and the selected gas.
+4.123 4.125 Air
+4.123 4.125 Air
+4.123 4.125 Air
+4.123 4.125 Air
+4.124 4.125 Air
+4.125 4.125 Air
VC Series Volumetric Flow Controller Data Format
For mass ow controllers, there are 6 columns of data representing pressure, temperature, volumetric
ow, mass ow and the selected gas. The rst column is absolute pressure (normally in PSIA), the
second column is temperature (normally in °C), the third column is volumetric ow rate (in the units
specied at time of order and shown on the display), and the fourth column is mass ow (also in the
units specied at time of order and shown on the display). For instance, if the meter was ordered in
units of SCFM, the display on the meter would read 2.004 SCFM and the last two columns of the output
below would represent volumetric ow and mass ow in CFM and SCFM respectively.
+014.70 +025.00 +02.004 +02.004 2.004 Air
+014.70 +025.00 +02.004 +02.004 2.004 Air
+014.70 +025.00 +02.004 +02.004 2.004 Air
+014.70 +025.00 +02.004 +02.004 2.004 Air
+014.70 +025.00 +02.004 +02.004 2.004 Air
+014.70 +025.00 +02.004 +02.004 2.004 Air
MC Series Mass Flow Controller Data Format
24
Sending a Simple Script File to HyperTerminal®
It is sometimes desirable to capture data for an extended period of time. Standard streaming mode
information is useful for short term events, however, when capturing data for an extended period of
time, the amount of data and thus the le size can become too large very quickly. Without any special
programming skills, the user can use HyperTerminal and a text editing program such as Microsoft Word
to capture text at user dened intervals.
1. Open your text editing program, MS Word for example.
2. Set the cap lock on so that you are typing in capital letters.
3. Beginning at the top of the page, type A<Enter> repeatedly. If you’re using MS Word, you can tell how
many lines you have by the line count at the bottom of the screen. The number of lines will correspond
to the total number of times the ow device will be polled, and thus the total number of lines of data it
will produce.
For example: A
A
A
A
A
A
will get a total of six lines of data from the ow meter, but you can enter as many as you like.
The time between each line will be set in HyperTerminal.
4. When you have as many lines as you wish, go to the File menu and select save. In the save dialog
box, enter a path and le name as desired and in the “Save as Type” box, select the plain text (.txt)
option. It is important that it be saved as a generic text le for HyperTerminal to work with it.
5. Click Save.
6. A le conversion box will appear. In the “End Lines With” drop down box, select CR Only. Everything
else can be left as default.
7. Click O.K.
8. You have now created a “script” le to send to HyperTerminal. Close the le and exit the text editing
program.
9. Open HyperTerminal and establish communication with your ow device as outlined in the manual.
10. Set the ow device to Polling Mode as described in the manual. Each time you type A<Enter>, the
meter should return one line of data to the screen.
11. Go to the File menu in HyperTerminal and select “Properties”.
12. Select the “Settings” tab.
13. Click on the “ASCII Setup” button.
14. The “Line Delay” box is defaulted to 0 milliseconds. This is where you will tell the program how often
to read a line from the script le you’ve created. 1000 milliseconds is one second, so if you want a line
of data every 30 seconds, you would enter 30000 into the box. If you want a line every 5 minutes, you
would enter 300000 into the box.
15. When you have entered the value you want, click on OK and OK in the Properties dialog box.
16. Go the Transfer menu and select “Send Text File…” (NOT Send File…).
17. Browse and select the text “script” le you created.
18. Click Open.
19. The program will begin “executing” your script le, reading one line at a time with the line delay you
specied and the ow device will respond by sending one line of data for each poll it receives, when it
receives it.
You can also capture the data to another le as described in the manual under “Collecting Data”. You
will be simultaneously sending it a script le and capturing the output to a separate le for analysis.
25
Operating Principle
All M and V Series Gas Flow Meters (and MC and VC Series Gas Flow Controllers) are based on the
accurate measurement of volumetric ow. The volumetric ow rate is determined by creating a pressure
drop across a unique internal restriction, known as a Laminar Flow Element (LFE), and measuring
differential pressure across it. The restriction is designed so that the gas molecules are forced to move
in parallel paths along the entire length of the passage; hence laminar (streamline) ow is established
for the entire range of operation of the device. Unlike other ow measuring devices, in laminar ow
meters the relationship between pressure drop and ow is linear. The underlying principle of operation
of the 16 Series ow meters is known as the Poiseuille Equation:
Q = (P1-P2)�r4/8ηL (Equation 1)
Where: Q = Volumetric Flow Rate
P1 = Static pressure at the inlet
P
= Static pressure at the outlet
2
r = Radius of the restriction
η = (eta) absolute viscosity of the uid
L = Length of the restriction
Since �, r and L are constant; Equation 1 can be rewritten as:
Q = K (∆P/η) (Equation 2)
Where K is a constant factor determined by the geometry of the restriction. Equation 2 shows the linear
relationship between volumetric ow rate (Q) differential pressure (∆P) and absolute viscosity (η) in a
simpler form.
Gas Viscosity: In order to get an accurate volumetric ow rate, the gas being measured must be
selected (see Gas Select Mode, page 14). This is important because the device calculates the ow rate
based on the viscosity of the gas at the measured temperature. If the gas being measured is not what
is selected, an incorrect value for the viscosity of the gas will be used in the calculation of ow, and the
resulting output will be inaccurate in direct proportion to the difference in the two gases viscosities.
Gas viscosity, and thus gas composition, can be very important to the accuracy of the meter. Anything
that has an effect on the gas viscosity (e.g. water vapor, odorant additives, etc.) will have a direct
proportional effect on the accuracy. Selecting methane and measuring natural gas for instance, will
result in a fairly decent reading, but it is not highly accurate (errors are typically < 0.6%) because
natural gas contains small and varying amounts of other gases such as butane and propane that result
in a viscosity that is somewhat different than pure methane.
Absolute viscosity changes very little with pressure (within the operating ranges of these meters) therefore
a true volumetric reading does not require a correction for pressure. Changes in gas temperature do
affect viscosity. For this reason, the M and V Series internally compensate for this change.
26
Other Gases: M Series Flow Meters/Controllers can easily be used to measure the ow rate of gases
other than those listed as long as “non-corrosive” gas compatibility is observed. For example, a ow
meter that has been set for air can be used to measure the ow of argon.
The conversion factor needed for measuring the ow of different gases is linear and is simply determined
by the ratio of the absolute viscosity of the gases. This factor can be calculated as follows:
Qog = Q1 [η1 / ηog ]
Where: Q1 = Flow rate indicated by the ow meter
η1 = Viscosity of the calibrated gas at the measured temp.
Qog = Flow rate of the alternate gas
η
= Viscosity of the alternate gas at the measured temp.
og
Say we have a meter set for air and we want to ow argon through it. With argon owing through the
meter, the display reads 110 SLPM. For ease of calculation, let us say the gas temperature is 25°C.
What is the actual ow of argon?
Qog = Actual Argon Flow Rate
Q1 = Flow rate indicated by meter (110 SLPM)
η1 = Viscosity of gas selected or calibrated for by the meter at the
measured temp.
ηog = Viscosity of gas owing through the meter at the measured temp.
At 25°C, the absolute viscosity of Air (η1) is 184.918 micropoise.
At 25°C, the absolute viscosity of Argon (ηog) is 225.593 micropoise.
So, the actual ow of Argon through the meter is 90.17 SLPM. As you can see, because the Argon gas
is more viscous than the Air the meter is set for, the meter indicates a higher ow than the actual ow.
A good rule of thumb is: “At a given ow rate, the higher the viscosity, the higher the indicated ow.”
Volume Flow vs. Mass Flow
: At room temperature and low pressures the volumetric and mass ow
rate will be nearly identical, however, these rates can vary drastically with changes in temperature and/
or pressure because the temperature and pressure of the gas directly affects the volume. For example,
assume a volumetric ow reading was used to ll balloons with 250 mL of helium, but the incoming
line ran near a furnace that cycled on and off, intermittently heating the incoming helium. Because
the volumetric meter simply measures the volume of gas ow, all of the balloons would initially be the
same size. However, if all the balloons are placed in a room and allowed to come to an equilibrium
temperature, they would generally all come out to be different sizes. If, on the other hand, a mass ow
reading were used to ll the balloons with 250 standard mL of helium, the resulting balloons would
initially be different sizes, but when allowed to come to an equilibrium temperature, they would all turn
out to be the same size.
This parameter is called corrected mass ow because the resulting reading has been compensated
for temperature and pressure and can therefore be tied to the mass of the gas. Without knowing the
temperature and pressure of the gas and thus the density, the mass of the gas cannot be determined.
27
Once the corrected mass ow rate at standard conditions has been determined and the density at
standard conditions is known (see the density table at the back of this manual), a true mass ow can
be calculated as detailed in the following example:
Mass Flow Meter Reading = 250 SCCM (Standard Cubic Centimeters/Minute)
Gas: Helium
Gas Density at 25C and 14.696 PSIA = .16353 grams/Liter
True Mass Flow = (Mass Flow Meter Reading) X (Gas Density)
True Mass Flow = (250 CC/min) X (1 Liter / 1000 CC) X (.16353 grams/Liter)
True Mass Flow = 0.0409 grams/min of Helium
Volumetric and Mass Flow Conversion: In order to convert volume to mass, the density of the gas
must be known. The relationship between volume and mass is as follows:
Mass = Volume x Density
The density of the gas changes with temperature and pressure and therefore the conversion of
volumetric ow rate to mass ow rate requires knowledge of density change. Using ideal gas laws, the
effect of temperature on density is:
ρ
/ ρs = Ts / T
a
a
Where: ρa = density @ ow condition
T
= absolute temp @ ow condition in °Kelvin
a
ρs = density @ standard (reference ) condition
Ts = absolute temp @ standard (reference) condition in °Kelvin
ºK = ºC + 273.15 Note: ºK=ºKelvin
The change in density with pressure can also be described as:
ρa / ρs = Pa / P
s
Where: ρa = density @ ow condition
Pa = ow absolute pressure
ρs = density @ standard (reference ) condition
Ps = Absolute pressure @ standard (reference) condition
Therefore, in order to determine mass ow rate, two correction factors must be applied to volumetric
rate: temperature effect on density and pressure effect on density.
Compressibility: Heretofore, we have discussed the gasses as if they were “Ideal” in their characteristics.
The ideal gas law is formulated as:
PV=nRT where: P = Absolute Pressure
V = Volume (or Volumetric Flow Rate)
n = number moles (or Molar Flow Rate)
R = Gas Constant (related to molecular weight)
T = Absolute Temperature
Most gasses behave in a nearly ideal manner when measured within the temperature and pressure
limitations of our products. However, some gasses (such as propane and butane) can behave in a less
than ideal manner within these constraints. The non-ideal gas law is formulated as:
PV=ZnRT
Where: “Z” is the compressibility factor. This can be seen in an increasingly blatant manner as gasses
approach conditions where they condense to liquid. As the compressibility factor goes down (Z=1 is
the ideal gas condition), the gas takes up less volume than what one would expect from the ideal gas
calculation.
28
This reduces to: Pa Va / Za Ta = Ps Vs / Zs Ts , eliminating R and n.
M Series mass ow meters/controllers model gas ows based upon the non-ideal gas characteristics
of the calibrated gas. The ow corrections are normally made to 25 C and 14.696 PSIA and the
compressibility factor of the gas under those conditions. This allows the user to multiply the mass ow
rate by the density of the real gas at those standard conditions to get the mass ow rate in grams per
minute.
Because we incorporate the compressibility factor into our ‘full gas model’; attempts to manually
compute mass ows from only the P, V, and T values shown on the display will sometimes result in
modest errors.
Note: Although the correct units for mass are expressed in grams, kilograms, etc. it has become standard
that mass ow rate is specied in SLPM (standard liters / minute), SCCM (standard cubic centimeters
/ minute) or SmL/M (standard milliliters / minute).
This means that mass ow rate is calculated by normalizing the volumetric ow rate to some standard
temperature and pressure (STP). By knowing the density at that STP, one can determine the mass ow
rate in grams per minute, kilograms per hour, etc.
STP is usually specied as the sea level conditions; however, no single standard exists for this
convention. Examples of common reference conditions include:
0°C and 14.696 PSIA
25°C and 14.696 PSIA
0°C and 760 torr (mmHG)
70°F and 14.696 PSIA
68°F and 29.92 inHG
20°C and 760 torr (mmHG)
M Series Flow Meters/Controllers reference 25ºC and14.696 PSIA (101.32kPa) - unless ordered
otherwise and specied in the notes eld of the calibration sheet.
Standard Gas Data Tables: We have incorporated the latest data sets from NIST (including their
REFPROP 7 data) in our products’ built-in gas property models. Be aware that calibrators that you may
be spot checking against may be using older data sets such as the widely distributed Air Liquide data.
This may generate apparent calibration discrepancies of up to 0.6% of reading on well behaved gases
and as much as 3% of reading on some gases such as propane and butane, unless the standard was
directly calibrated on the gas in question. As the older standards are phased out of the industry, this
difference in readings will cease to be a problem. If you see a difference between the meter and your in-
house standard, in addition to calling Apex, call the manufacturer of your standard for clarication as to
which data set they used in their calibration. This comparison will in all likelihood resolve the problem.
Gas Viscosities, Densities and Compressibilities at 0o C
31
Volumetric Flow Meters Under Pressure
16 Series Volumetric Gas Flow Meters and Flow Controllers are intended for use in low
pressure applications. This is because an accurate measurement of the volumetric ow rate
by means of differential pressure requires the ow at the differential pressure sensor to be in a
laminar state. The state of the ow is quantied by what is known as the Reynolds Number. If
the Reynolds Number gets above a certain point, generally accepted as approximately 2000,
the ow will become non-laminar. The Reynolds Number for a given Newtonian uid ow is
dened as:
Re =
Where: ρ = densityV = average velocity
L = Constant determined by length and geometry of passage
η = absolute viscosity
From this relationship we see that increasing the gas density or velocity increases the Reynolds
Number, and increasing the gas viscosity decreases the Reynolds number. For a given gas in
a given meter at a given temperature, L and η are roughly xed constants.
For the purpose of illustration, let us put two 100 (S)LPM ow meters, identical in every way
except that one is a volumetric ow meter and one is a mass ow meter, in series with one
another in a pipeline. Now let us pass a small constant air ow through the meters, thus xing
the velocity V though both meters. With the ow xed, let us begin increasing the pressure,
and thus the density ρ. The mass ow meter, which is measuring the absolute pressure and
compensating for the density change registers this pressure increase as an increase in mass
ow rate because the number of molecules of gas keeps going up in the xed volume of ow.
In addition, the Reynolds number has increased proportionately with the pressure increase
because the density goes up with the pressure. If you increase the pressure high enough,
the mass ow meter will max out at 100 SLPM, the Reynolds number has increased fairly
dramatically, and the volumetric meter still registers your small xed ow rate.
ρVL/η
Now if we maintain the higher pressure and try to take the volumetric meter up to its published
full scale ow of 100 LPM, our density ρ AND our velocity V will be high, which often results
in a high Reynolds number and non-laminar ow. When the ow is non-laminar, the Poiseuille
Equation upon which we base our volumetric ow measurement is no longer valid and the
meter reading is therefore no longer valid.
Gas properties also need to be taken into account in deciding whether you can use a volumetric
ow meter at a particular line pressure. Helium, which has a relatively low density and a
relatively high viscosity at standard conditions, can generally get away with higher pressures in
a volumetric ow meter. Propane, on the other hand, has a relatively high density and relatively
low viscosity making it a considerably more difcult gas to measure at higher pressures in a
volumetric ow meter. In air, most volumetric meters make valid full scale measurements up to
10-15 PSIG line pressure.
32
TROUBLESHOOTING
Display does not come on or is weak.
Check power and ground connections.
Flow reading is approximately xed either near zero or near full scale regardless of actual line
ow.
Differential pressure sensor may be damaged. Avoid installations that can subject sensor to pressure
drops in excess of 10 PSID. A common cause of this problem is instantaneous application of highpressure gas as from a snap acting solenoid valve upstream of the meter. Damage due to excessive
pressure differential is not covered by warranty.
Displayed mass ow, volumetric ow, pressure or temperature is ashing and message MOV,
VOV, POV or TOV is displayed:
Our ow meters and controllers display an error message (MOV = mass overrange, VOV = volumetric
overrange, POV = pressure overrange, TOV = temperature overrange) when a measured parameter
exceeds the range of the sensors in the device. When any item ashes on the display, neither the
ashing parameter nor the mass ow measurement is accurate. Reducing the value of the ashing
parameter to within specied limits will return the unit to normal operation and accuracy.
After installation, there is no ow.
Apex MC and VC controllers incorporate normally closed valves and require a set-point to operate.
Check that your set-point signal is present and supplied to the correct pin and that the correct input
is selected under the Input list in the control set up mode screen. Also check that the unit is properly
grounded.
The ow lags below the set-point.
Be sure there is enough pressure available to make the desired ow rate. If either the set-point signal line
and/or the output signal line is relatively long, it may be necessary to provide heavier wires (especially
ground wiring) to negate voltage drops due to line wire length. An inappropriate PID tuning can also
cause this symptom if the D term is too large relative to the P term.
Meter does not agree with another meter I have in line.
Volumetric meters will often not agree with one another when put in series because they are affected
by pressure drops. Volumetric ow meters should not be compared to mass ow meters. Mass ow
meters can be compared against one another provided there are no leaks between the two meters and
they are set to the same standard temperature and pressure. Both meters must also be calibrated (or
set) for the gas being measured. M Series mass ow meters are normally set to Standard Temperature
and Pressure conditions of 25° C and 14.696 PSIA. Note: it is possible to special order meters with a
customer specied set of standard conditions. The calibration sheet provided with each meter lists its
standard conditions.
Controller is slow to react to a set-point change or imparts an oscillation to the ow.
An inappropriate PID tuning can cause these symptoms. Use at conditions considerably different than
those at which the device was originally set up can necessitate a re-tuning of the PID loop.
The output signal is lower than the reading at the display.
This can occur if the output signal is measured some distance from the meter as voltage drops in the
wires increase with distance. Using heavier gauge wires, especially in the ground wire, can reduce this
effect.
My volumetric controller reading is strange, inconsistent, or incorrect.
Make sure you use a volumetric ow controller only under low pressure (close to atmospheric) and with
little to no back pressure for accurate readings. Mass controllers should be used for higher pressure
applications. See “Volumetric Flow Meters Under Pressure” page 30.
33
RS-232 Serial Communications is not responding.
Check that your meter is powered and connected properly. Be sure that the port on the computer to which
the meter is connected is active. Conrm that the port settings are correct per the RS-232 instructions
in this manual (Check the RS-232 communications select screen for current meter readings). Close
Hyperterminal® and reopen it. Reboot your PC.
Slower response than specied.
MC and VC Series controllers feature an RS-232 programmable Geometric Running Average (GRA).
Depending on the full scale range of the meter, it may have the GRA set to enhance the stability/
readability of the display, which would result in slower perceived response time. If you require the fastest
possible response time, please consult the factory for written instructions on adjusting the GRA.
Jumps to zero at low ow.
MC and VC Series controllers feature an RS-232 programmable zero deadband. The factory setting is
usually 0.5% of full scale. This can be adjusted via RS-232 programming between NONE and 6.375%
of full scale. Contact the factory for more information.
Discrepancies between old and new units.
Please see “Standard Gas Data Tables” explanation on page 29.
Maintenance and Recalibration
General: MC and VC Series Flow Controllers require minimal maintenance. They have no moving
parts. The single most important thing that affects the life and accuracy of these devices is the quality
of the gas being measured. The controller is designed to measure CLEAN, DRY, NON-CORROSIVE
gases. A 20 micron lter (50 micron for 50LPM and up) mounted upstream of the controller is highly
recommended. Moisture, oil, and other contaminants can affect the laminar ow elements and/or reduce
the area that is used to calculate the ow rate. This directly affects the accuracy.
Recalibration: The recommended period for recalibration is once every year. Providing that the CLEAN,
DRY, and NON-CORROSIVE mantra is observed, this periodic recalibration is sufcient. A label located
on the back of the meter lists the recalibration due date. The meter should be returned to the factory for
recalibration near the listed due date. Before calling to schedule a recalibration, please note the serial
number on the back of the meter. The Serial Number, Model Number, and Date of Manufacture are also
available on the Manufacture Data 2 screen (page 16).
Cleaning: MC and VC Series Flow Controllers require no periodic cleaning. If necessary, the outside of
the controller can be cleaned with a soft dry rag. Avoid excess moisture or solvents.
For repairs, recalibrations, or recycling of this product contact:
Apex Vacuum
222 Riverstone Drive
Canton, GA 30114
USA
Ph. 404-474-3115
Website: www.apexvacuum.com
34
Technical Data for Micro Flow Mass & Volumetric Flow Controllers
1. Volumetric meters only: Operating pressure limitations determined by Reynolds number thresholds. For
operating pressures >10PSIG, please contact the manufacturer for more details.
2. 24 volt applications should specify 24 volt coils.
At calibration conditions after tare
At calibration conditions after tare
PSIG
0-5 Vdc or 0-10Vdc or 420mA
2
Mechanical Specications
Full Scale Flow
Mass Controller
0.5SCCM up to
1SCCM
2SCCM up to
50SCCM
∗ Units ≤50SCCM F.S. are shipped with 10-32 Male Buna-N O-ring face seal to 1/8” Female NPT ttings.
These adaptor ttings were selected for customer convenience in process connection. It should be noted
that the 1/8” Female NPT introduces additional dead volume. To minimize dead volume, please see
Accessories for the 10-32 Male to 1/8”OD compression tting.
1. Compatible with Beswick®, Swagelok® tube, Parker®, face seal, push connect and compression adapter
ttings.
2. Lower Pressure Drops Available, please contact the manufacturer.
Full Scale Flow
Volumetric
Controller
0.5CCM up to
1CCM
2CCM up to
50CCM
Mechanical
Dimensions
3.9”H x 3.5”W x 1.1”D
Process
Connections
10-32 Female
Thread*
1
(PSID)
0.5
1.0
Pressure Drop2
Dimensional Drawings: page 38
35
Technical Data for Low Flow Mass & Volumetric Flow Controllers
1. Volumetric meters only: Operating pressure limitations determined by Reynolds number thresholds. For
operating pressures >10PSIG, please contact the manufacturer for more details.
2. 24 volt applications should specify 24 volt coils.
At calibration conditions after tare
At calibration conditions after tare
PSIG
0-5 Vdc or 0-10Vdc or 420mA
2
Mechanical Specications
Full Scale Flow
Mass Controller
>50SCCM to
500SCCM
1SLPM1LPM
5SLPM5LPM2.0
10SLPM10LPM5.0
20SLPM20LPM
1. Compatible with Beswick®, Swagelok® tube, Parker®, face seal, push connect and compression adapter
ttings.
2. Lower Pressure Drops Available, please contact the manufacturer.
Full Scale Flow
Volumetric
Controller
>50CCM to
500CCM
Mechanical
Dimensions
4.1”H x 3.6”W x 1.1”D
4.2”H x 2.4”W x 1.1”D
Process
Connections
1/8” NPT Female
Pressure Drop2
1
(PSID)
1.0
1.5
20.0
Dimensional Drawings: page 38, 39
36
Technical Data for Moderate Flow Mass & Volumetric Flow Controllers
1. Volumetric meters only: Operating pressure limitations determined by Reynolds number thresholds. For
operating pressures >10PSIG, please contact the manufacturer for more details.
At calibration conditions after tare
At calibration conditions after tare
PSIG
0-5 Vdc or 0-10Vdc or 420mA
Mechanical Specications
Full Scale Flow
Mass Controller
>20SLPM>20LPM4.7”H x 6.9”W x 2.3”D
100SLPM100LPM4.7”H x 7.4”W x 2.3”D
250SLPM250LPM
1. Compatible with Beswick®, Swagelok® tube, Parker®, face seal, push connect and compression adapter
ttings.
2. Lower Pressure Drops Available, please contact the manufacturer.
Full Scale Flow
Volumetric
Controller
Mechanical
Dimensions
5.0”H x 6.9”W x 2.3”D1/2” NPT Female
Process
Connections
1/4” NPT Female
1
(PSID)
2.5
5.0
10.0
Pressure Drop2
Dimensional Drawings: page 39, 40
37
Technical Data for High Flow Mass & Volumetric Flow Controllers
High Accuracy Option± 0.4% of Reading ±0.2% of Full Scale
Repeatability± 0.2%Full Scale
Operating Range1% to 100% Full ScaleMeasure
Typical Response Time100Milliseconds (Adjustable)
Standard Conditions (STP)25ºC & 14.696PSIANot ApplicableMass Reference Conditions
Operating Temperature−10 to +50ºCelsius
Zero Shift0.02%Full Scale / ºCelsius / Atm
Span Shift0.02%Full Scale / ºCelsius / Atm
Humidity Range0 to 100%Non–Condensing
Controllable Flow Rate102.4%Full Scale
Maximum Pressure125125*PSIG
Input /Output Signal Digital
Input / Output Signal AnalogMass FlowVolumetric Flow0-5Vdc
Optional Input / Output
Signal Secondary Analog
Electrical Connections8 PinMini-DIN
Supply Voltage24 to 30 Vdc
Supply Current1.0Amp maximum
Mounting Attitude Sensitivity0%
Warm-up Time< 1Second
Wetted Materials
* Volumetric meters only: Operating pressure limitations determined by Reynolds number thresholds. For
operating pressures >10PSIG, please contact the manufacturer for more details.
1. Compatible with Beswick®, Swagelok® tube, Parker®, face seal, push connect and compression adapter
ttings.
2. Lower Pressure Drops Available, Please contact the manufacturer.
Controllers ≥ 500 (S)LPM utilize a low drop valve that seals off only in the positive ow direction. If
the downstream pressure exceeds the inlet pressure, reverse ow will occur.
Full Scale Flow
Volumetric
Controller
Mechanical
Dimensions
5.0”H x 7.4”W x 2.3”D3/4” NPT Female
Process
Connections
1
Pressure Drop2
(PSID)
4.1
Dimensional Drawings: page 40
38
394041
Option: Totalizing Mode
16 Series Flow Meters and Controllers can be purchased with the Totalizing Mode option. This option
adds an additional mode screen that displays the total ow (normally in the units of the main ow
screen) that has passed through the meter or controller since the last time the totalizer was cleared.
The Totalizing Mode screen shown below is accessed by pushing the “MODE” button until the label
over it reads “Total”. If your meter or controller is ordered with Totalizing Mode option, pushing the
“Mode” button once will bring up the “Totalizing Mode” display. Pushing “Mode” a second time will bring
up the “Select Menu” display. Pushing it a third time will return you to the Main Mode Sreen.
Hours Mass Clear
0.3 0.00
Mass
SLtr
Air
+0.0 SCCM
Total
Counter – The counter can have as many as six digits. At the time of order, the customer must specify
the resolution of the count. This directly affects the maximum count. For instance, if a resolution of
1/100ths of a liter is specied on a meter which is totalizing in liters, the maximum count would be
9999.99 liters. If the same unit were specied with a 1 liter resolution, the maximum count would be
999999 liters.
Rollover – The customer can also specify at the time of order what the totalizer is to do when the
maximum count is reached. The following options may be specied:
No Rollover – When the counter reaches the maximum count it stops counting until the counter is
cleared.
Rollover – When the counter reaches the maximum count it automatically rolls over to zero and continues
counting until the counter is cleared.
Rollover with Notication – When the counter reaches the maximum count it automatically rolls over to
zero, displays an overow error, and continues counting until the counter is cleared.
Hours.–.The display will show elapsed time since the last reset in 0.1 hour increments. The maximum
measurable elapsed time is 6553.5 hours (about nine months). The hours count resets when the “clear”
button is pushed, an RS-232 clear is executed or on loss of power
Clear – The counter can be reset to zero at any time by pushing the dynamically labeled “Clear” button
located above the upper right corner of the display. To clear the counter via RS-232, establish serial
communication with the meter or controller as described in the RS-232 section of the manual. To reset
the counter, enter the following commands:
In Streaming Mode: $$T <Enter>
In Polling (addressable) Mode: Address$$T <Enter> (e.g. B$$T <Enter>)
42
Option: Local Set-Point Module
The Local Set-Point Module (LSPM) is designed to provide the user with a simple “turn of the dial”
method of changing a ow or pressure controller
set-point.
DC-62 Double Ended
8Pin Mini-DIN Cable
The LSPM features a set-point control dial, a digital
LED display which can be set to show either the
set-point or the actual process measurement, and
a tracking alarm LED which glows red whenever
the actual process measurement deviates from the
set-point by more than 2% of full scale. This device
is handy as a remote control/display device where
the controller is out of convenient reach or view.
It is supplied with a 6’ double ended cable to run
between the controller and the LSPM. There is an
additional 8 pin Mini-DIN port on the LSPM that
allows access to normal signal/power functions of
the controller’s Mini-DIN port.
8 Pin Mini-DIN connector connects to controller or to external device for power or output
•
signal recording
LCD Display can display either the set-point or the process measurement.
•
Set-point Adjustment Knob provides simple “dial it in” process changes.
•
Display button switches display between actual set-point and measured ow parameter.
•
LED indicator switches from green to red when the measured parameter deviates from the
•
set-point by more than 2% of full scale.
Operation Notes: The LSPM requires a double ended DC-62 8 Pin Mini-DIN cable connected
between either the top or bottom connector socket of the LSPM to the connector socket on top of
the controller. The two connector sockets on the LSPM are “pass through” connected so that the
unused socket can be connected to a DC-61 single ended cable for connection of output signals
and/or power. Appropriate power can be connected to either the LSPM or the controller, whichever
is more convenient. Unless specially ordered otherwise, the LSPM utilizes the 5.12 Vdc output pin
on the controller (pin 2) as a source. The 5.12 volts is connected through the potentiometer and
returned to the controller on the set-point pin (pin 4) as a 0 though 5.12 Vdc input signal depending
on the position of the adjustment knob.
43
Accessories
Local Set-Point Module
Multi-Drop Box
8 Pin Male Mini-DIN connector cable, single ended, 6 foot length