Apex Digital Precision Gas Flow Meter User Manual

16 Series Mass and Volumetric Flow Meters

Precision Gas Flow Meter

Operating Manual

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.

10/24/06 Rev. 0 DOC-APEXMAN16

Table of Contents Page

Installation 5 Plumbing Mounting Application

Power and Signal Connections 6 RS-232 Digital Output Signal 7 Standard Voltage (0-5 Vdc) Output Signal 7 Optional 0-10 Vdc Output Signal 7 Optional Current (4-20 mA) Output Signal 7 Optional 2nd Analog Output Signal 7 M Series Mass Flow Meter Operation 10

Main Mode Tare Gas Absolute Pressure Gas Temperature Volumetric Flow Rate 11 Mass Flow Rate Flashing Error Message 11

Select Menu Mode 12 Gas Select Mode 12 Communication Select Mode 13 Unit ID 13

Baud Data Rate Manufacturer Data Mode

V Series Volumetric Flow Meter Operation 15

Main Mode Tare Flashing Error Message 16

Select Menu Mode 16 Gas Select Mode 16 Communication Select Mode 16

Manufacturer Data Mode

RS-232 Output and Input 16 Conguring HyperTerminal® 16 Changing from Streaming to Polling Mode 17

Tare

Gas Select 17

5 5 5

10 10 11 11

13 13

15 15

Table of Contents Page

Collecting Data Data Format Sending a Simple Script File to HyperTerminal® 20 Operating Principle Gas Viscosity 21 Other Gases

Volume Flow vs. Mass Flow 23 Volumetric Flow and Mass Flow Conversion 23

Compressibility

Standard Gas Data Tables 24 Gas Viscosities and Densities Table 25 Volumetric Flow Meters Under Pressure 26

Troubleshooting 27 Maintenance and Recalibration Warranty Technical Specications 29 Dimensional Drawings

Additional Information

Option: Totalizing Mode Option: Battery Pack Accessories Flow Conversion Table Calibration Certicate Pocket 40

19 19

36 37 39 39

Table of Figures

Figure 1. 8 Pin Mini-DIN Connector

Figure 2. Mini-DIN to DB-9 Connection for RS-232 Signals 8 Figure 3. Typical Multiple Device (Addressable) Wiring Conguration 8

Figure 4. Optional Industrial Connector

Figure 5. Proper Set Up for Remote Tare on Meters 9 Figure 6. Main Mode Display, M Series Flow Meter 10 Figure 7. Select Menu Display 12 Figure 8. Gas Select Display 12 Figure 9. Communication Select Display 13

Figure 10. Manufacturer Data Display

Figure 11. Main Mode Display, V Series Flow Meter 15

Thank you for purchasing an Apex Gas Flow Meter. 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:

M Series 16 Bit Mass Gas Flow Meters V Series 16 Bit Volumetric Gas Flow Meters

Installation

Plumbing

All M or V Series Gas Flow Meters 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 meter. The inlet and outlet ports are equal in size and symmetric (inline). The port sizes (process connections) and mechanical dimensions for different ow ranges are shown on pages 29-32.

Meters with 10-32 ports have o-ring face seals and require no further sealant or tape. On other meters,

avoid the use of pipe dopes or sealants on the ports as these compounds can cause permanent damage

to the meter should they get into the ow stream. Use of thread sealing Teon 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 meters with full scale ranges of 1(S)LPM or less and a 50 micron lter be installed upstream of meters with full scale ranges above 1(S)LPM.

Mounting

All M or V Series Gas Flow Meters have mounting holes for convenient mounting to at panels. These

meters are position insensitive and can be mounted in any orientation. The sizes and dimensions for

the mounting holes are shown on pages 33-35.

Application

Maximum operating line pressure is 145 PSIG (1000 kPa).

Caution: Exceeding the maximum specied line pressure may cause permanent damage to the

solid-state differential pressure transducer.

If the line pressure is higher than 145 PSIG (1000 kPa), a pressure regulator should be used upstream from the ow meter to reduce the pressure to 145 PSIG (1000 kPa) or less if possible. Although the meter’s operation is uni-directional, reversing the ow direction will inict no damage as long as the maximum specied limits are not exceeded.

Note: Avoid installations (such as snap acting solenoid valves upstream) that apply instantaneous

high pressure to the meter as permanent damage to the differential pressure sensor could result.

This damage is not covered under warranty!

Power and Signal Connections

7 8

1 2

4 5

AC/DC Adapter Jack

Power can be supplied to your M or V Series meter 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

between 7 and 30 volts is required to use the power jack. The adapter current should be at least 100mA. The power jack accepts 2.1 mm female power plugs with positive centers. Cables and AC/DC adaptors may purchased from Apex (see Accessories page 42) and are commonly available at local electronics

suppliers. Alternatively, power can be supplied through the Mini-DIN connector as shown below:

Pin Function

1 Inactive or 4-20mA Primary Output Signal Black

3 RS-232 Input Signal Red 4 Analog Input Signal = Remote Tare (Ground to Tare) Orange 5 RS-232 Output Signal Yellow 6 0-5 Vdc (or 0-10 Vdc) Output Signal Green 7 Power In (7-30 Vdc, 100mA) or (15-30Vdc for 4-20mA units) Blue 8 Ground (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.

Underlined Items in the above table are optional congurations that are noted on the unit’s calibration sheet.

Static 5.12 Vdc or Secondary Analog Output (4-20mA, 5Vdc, 10Vdc) or Basic Alarm

4 5

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 reects the system bus voltage and can be used as a source for the input signal.

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

2. Adapter cables are available from the manufacturer or they can be constructed in the eld with parts

from an electronics supply house. In Figure 2, 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 2. (See page 16 for details on accessing RS-232 output.)

Standard Voltage (0-5 Vdc) Output Signal

All M or V Series ow meters 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 meter 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 meter 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 meter 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 meter to determine which output signals were ordered.) The current signal is 4 mA at 0 ow and 20 mA at the meter’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 meter 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 meter 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 meter 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.

DB-9 Serial Port

5----------Ground--------------------------------------Ground----------8 3----------Transmit------------------------------------Receive---------3 2----------Receive-------------------------------------Transmit--------5

8 Pin Mini-DIN Port

1 2 3 4 5

6 7

8 9

Figure 2. Mini-DIN to DB-9 Connection for RS-232 Signals

Purple (Ground)

Red

Yellow

Unit A

Purple

Red

Yellow

Unit B

Purple

Red

Yellow

Unit C

Female Serial Cable Front

Figure 3. Typical Multiple Device (Addressable) Wiring Conguration

An optional industrial connector is also available:

Pin Function Cable Color

Power In ( + )

2 RS-232 Output Blue 3 RS-232 Input Signal White 4 Remote Tare (Ground to Tare) Green 5 Ground (commom for power,

communications and signals)

6 Signal Out (Voltage or Current as ordered) Brown

Figure 4. Optional Industrial Connector

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 meter options ordered.

Red

Black

Figure 5. Proper set up for remote tare on meters (Momentarily ground Pin 4 to Tare)

M Series Mass Flow Meter Operation

The M Series Mass Flow Meter provides a multitude of useful ow data in one simple, rugged device. The M Series can have several display “modes” depending on how the device is ordered. All M Series meters have a default Main Mode, Select Menu Mode, a Gas Select Mode (the Gas Select Mode may not be available on meters calibrated for a custom gas or blend), a Communication Select Mode and a Manufacturer Data Mode. (In addition, your device may have been ordered with a Totaliizing Mode, page 36.) The device defaults to Main Mode as soon as power is applied to the meter.

Main Mode

The main mode display 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 Tare

+13.49 +22.73

SCCM Air

+0.000 +0.000

Volume Mass Main

MASS

Figure 6. Main Mode Display, M Series Flow Meter

The “MODE” button in the lower right hand corner toggles the display between Main Display and the

Select Menu Display.

Tare – Pushing the dynamically labeled “Tare” button in the upper right hand corner tares the ow meter and provides it with a reference point for zero ow. This is a simple but important step in obtaining accurate measurements. It is good practice to “zero” the ow meter each time it is powered up. If the ow reading varies signicantly from zero after an initial tare, give the unit a minute or so to warm up

and re-zero it.

If possible, zero the unit near the expected operating pressure by positively blocking the ow downstream of the ow meter prior to pushing the “Tare” button. Zeroing the unit while there is any ow will directly affect the accuracy by providing a false zero point. If in doubt about whether a zero ow condition exists,

remove the unit from the line and positively block both ports before pressing the “Tare” button. If the unit

reads a signicant negative value when removed from the line and blocked, it is a good indication that it was given a false zero. It is better to zero the unit at atmospheric pressure and a conrmed no ow

conditions than to give it a false zero under line pressure.

Note: A remote tare can be achieved by momentarily grounding pin 4 to tare as shown in Figure 5

on page 9.

Gas Absolute Pressure: The M Series ow meters 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.

Gas Temperature: The M Series ow meters also 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 meters 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 elsewhere in this manual. 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 meter 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 specied 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 display. Push “Mode” again to return to the Main Mode display. (Note: If your

meter was ordered with Totalizing Mode option (page 36), 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

Select

SELECT

Comm. Mfg.

RS-232 Data Menu

Figure 7. Select Menu Display

Gas Select Mode

The gas select mode is accessed by pressing the button above “Gas Select” on the Select Menu

display. The display will appear as shown in Figure 8 below.

PgUP PgDWN Main

H2 Hydrogen He Helium >N2 Nitrogen N2O Nitrous Oxide Ne Neon O2 Oxygen UP DOWN Gas

Figure 8. Gas Select Display

The selected gas is displayed on the default main mode display as shown in Figure 6, and is indicated

by the arrow in the Gas Select Mode display in Figure 8. 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

display. (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. The screen will appear as shown in Figure 9 below.

Select Main

Unit ID (A).....A

Baud (19200)....19200

Data Rate......Fast

Comm.

UP DOWN RS-232

Figure 9. Communication Select Display

Unit ID – Valid unit identiers are letters A-Z and @ (see Note below). This identier 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 or Main 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 or Main button. See the RS-232

Communications chapter in this manual 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.

Manufacturer Data

“Manufacturer Data” is accessed by pressing the “Mfg. Data” button on the Select Menu display (Figure

7). 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 M-10SLPM-D Serial No 27117 Date Mfg.11/07/2005 Calibrated By.DL

Software GP07R23

Mfg 2

Figure 10. Manufacturer Data Displays

V Series Volumetric Flow Meter Operation

The V Series can have several display “modes” depending on how the device is ordered. All V Series meters have a default Main Mode,a Select Menu Mode, a Gas Select Mode (the Gas Select Mode may not be available on meters calibrated for a custom gas or blend), a Communication Select Mode and a Manufacturer Data Mode. (In addition, your device may have been ordered with a Totaliizing Mode, page 36.) The device defaults to Main Mode as soon as power is applied to the meter. Note that volumetric meters are intended for use in near atmospheric conditions (Please see page 26).

Main Mode

The main mode display shows the volumetric ow in the units specied at time of order. In the ow

mode, only two buttons, Tare and Mode, are active as shown in Figure 11. The process gas that is

selected is shown directly under the ow units.

Tare

Volume

CCM Air

+0.000 Volume Main

Figure 11. Main Mode Display, V Series Flow Meter

The “MODE” button in the lower right hand corner toggles the display between the Main Display and

the Select Menu Display.

Tare – Pushing the dynamically labeled “Tare” button in the upper right hand corner tares the ow meter and provides it with a reference point for zero ow. This is a simple but important step in obtaining accurate measurements. It is good practice to “zero” the ow meter each time it is powered up and whenever a known zero ow condition exists. If the ow reading varies signicantly from zero after an

initial tare, give the unit a minute or so to warm up and re-zero it.

Zeroing the unit while there is any ow will directly affect the accuracy by providing a false zero point. If in doubt about whether a zero ow condition exists, remove the unit from the line and positively block both ports before pressing the “Tare” button. If the unit reads a signicant negative value when removed

from the line and blocked, it is a good indication that it was given a false zero. It is better to zero the

unit at atmospheric pressure and a conrmed “no ow” condition than to give it a false zero under line

pressure.

Note: A remote tare can be achieved by momentarily grounding pin 4 to tare as shown in Figure 5 on

page 9.

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 specied limits will return the unit to normal operation and accuracy.

Select Menu Mode

Pushing “Mode” once will bring up the “Select Menu” display (Figure 7, page 12). Push the button nearest your selection to go to the corresponding display. Push “Mode” again to return to the Main Mode

display. (Note: If your meter was ordered with Totalizing Mode option (page 36), 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 Select Mode

The Gas Select Mode is accessed by pressing the button above “Gas Select” on the Select Menu display. The display will appear as shown in Figure 8 (page 12). The selected gas is displayed on the

default main mode display as shown in Figure 11, and is indicated by the arrow in the gas select mode

display in Figure 8. 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 display.

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 13 for Communication Select mode instructions.

Manufacturer Data

“Manufacturer Data” is accessed by pressing the “Mfg. Data” button on the Select Menu display (Figure 7, page 12). 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 (Figure 10, page 14).

RS-232 Output and Input

Conguring HyperTerminal®:

Open your HyperTerminal® RS-232 terminal program (installed under the “Accessories” menu on

all Microsoft Windows operating systems). Select “Properties” from the le menu.

Click on the “Congure” 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 meter) 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.

Click on the “ASCII Setup” button and be sure the “Send Line Ends with Line Feeds” box is not

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.

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 identier 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.

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 identier or address. Unless otherwise specied 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 identier

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.

Tare –Tareing (or zeroing) the ow meter provides it with a reference point for zero ow. This is a simple but important step in obtaining accurate measurements. It is good practice to “zero” the ow meter each

time it is powered up. A unit may be Tared by following the instructions on page 10 or it may be Tared

via RS-232 input.

To send a Tare command via RS-232, enter the following strings:

In Streaming Mode: $$V<Enter>

In Polling Mode: Address$$V<Enter> (e.g. B$$V<Enter>)

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 meter display:

# GAS 0 Air Air 1 Argon Ar 2 Methane CH4 3 Carbon Monoxide CO 4 Carbon Dioxide CO2 5 Ethane C2H6 6 Hydrogen H2 7 Helium He 8 Nitrogen N2 9 Nitrous Oxide N2O

10 Neon Ne 11 Oxygen O2 12 Propane C3H8 13 normal-Butane n-C4H10 14 Acetylene C2H2 15 Ethylene C2H4 16 iso-Butane i-C2H10 17 Krypton Kr 18 Xenon Xe 19 Sulfur Hexauoride SF6 20 21 22 23 24 25 26 27

90% Helium / 7.5% Argon / 2.5% CO2

90% Argon / 8% CO2 / 2% Oxygen

75% Argon / 25% CO2

90% Argon / 10% CO2

92% Argon / 8% CO2

98% Argon / 2% CO2

75% CO2 / 25% Argon

75% Argon / 25% Helium

75% Helium / 25% Argon

(Praxair - Helistar® A1025)

(Praxair - Stargon® CS)

95% Argon / 5% Methane

C-25 C-10

C-8

C-2 C-75 A-75 A-25

A1025

Star29

P-5

For example, to select Propane, enter: $$12<Enter>

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 20.

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 meters, there are two columns of data representing volumetric ow rate in the units specied at time of order and the selected gas.

+4.123 Air +4.123 Air +4.123 Air +4.123 Air

+4.124 Air

+4.125 Air

V Series Volumetric Flow Meter Data Format

For mass ow meters, there are 5 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 specied at time of order and shown on the display), and the fourth column is mass ow (also in the units specied 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 Air +014.70 +025.00 +02.004 +02.004 Air +014.70 +025.00 +02.004 +02.004 Air +014.70 +025.00 +02.004 +02.004 Air +014.70 +025.00 +02.004 +02.004 Air +014.70 +025.00 +02.004 +02.004 Air

M Series Mass Flow Meter Data Format

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 dened 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 specied 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.

Operating Principle

All M or V Series Gas Flow Meters 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 P2 = Static pressure at the outlet

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 12). This is important because the device calculates the ow

ratebased 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 or V Series internally compensate for this change.

Other Gases: M Series Flow Meters 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

= Viscosity of the alternate gas at the measured temp.

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.

Qog = Q1 (η 1 / ηog) Qog = 110 SLPM (184.918 / 225.593) Qog = 90.17 SLPM

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.

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:

/ ρs = Ts / T

Where: ρa = density @ ow condition

Ta = absolute temp @ ow condition in °Kelvin

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

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.

This reduces to: P

Our mass ow meters 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 specied 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 specied as the sea level conditions; however, no single standard exists for this

convention. Examples of common reference conditions include:

Va / Za Ta = Ps Vs / Zs Ts , eliminating R and n.

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 reference 25ºC and14.696 PSIA (101.32kPa) - unless ordered otherwise.

Refer to the calibration sheet to conrm the reference point.

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 clarication as to

which data set they used in their calibration. This comparison will in all likelihood resolve the problem.

Gas

Number

0 Air Air 184.918 1.1840 0.9997 1 Ar Argon 225.593 1.6339 0.9994 2 CH4 Methane 111.852 0.6569 0.9982 3 CO Carbon Monoxide 176.473 1.1453 0.9997 4 CO2 Carbon Dioxide 149.332 1.8080 0.9949 5 C2H6 Ethane 93.540 1.2385 0.9924 6 H2 Hydrogen 89.153 0.08235 1.0006 7 He Helium 198.457 0.16353 1.0005 8 N2 Nitrogen 178.120 1.1453 0.9998

9 N2O Nitrous Oxide 148.456 1.8088 0.9946 10 Ne Neon 311.149 0.8246 1.0005 11 O2 Oxygen 204.591 1.3088 0.9994 12 C3H8 Propane 81.458 1.8316 0.9841 13 n-C4H10 normal-Butane 74.052 2.4494 0.9699 14 C2H2 Acetylene 104.448 1.0720 0.9928 15 C2H4 Ethylene 103.177 1.1533 0.9943 16 i-C4H10 iso-Butane 74.988 2.4403 0.9728 17 Kr Krypton 251.342 3.4274 0.9994 18 Xe Xenon 229.785 5.3954 0.9947 19 SF6 Sulfur Hexauoride 153.532 6.0380 0.9887 20 C-25 75% Argon / 25% CO2 205.615 1.6766 0.9987 21 C-10 90% Argon / 10% CO2 217.529 1.6509 0.9991 22 C-8 92% Argon / 8% CO2 219.134 1.6475 0.9992 23 C-2 98% Argon / 2% CO2 223.973 1.6373 0.9993 24 C-75 75% CO2 / 25% Argon 167.451 1.7634 0.9966 25 A-75 75% Argon / 25% Helium 230.998 1.2660 0.9997 26 A-25 75% Helium / 25% Argon 234.306 0.5306 1.0002

27 A1025

28 Star29

29 P-5 95% Argon / 5% Methane 223.483 1.5850 0.9993

*in micropoise (1 Poise = gram / (cm) (sec)) ** Grams/Liter (NIST REFPROP 7 database)

Short Form Long Form

90% Helium / 7.5% Argon /

2.5% CO2

(Praxair - Helistar® A1025)

90% Argon / 8% CO2

/ 2% Oxygen

(Praxair - Stargon® CS)

Viscosity*

25 deg C

14.696 PSIA

214.840 0.3146 1.0003

218.817 1.6410 0.9992

Density**

25 deg C

14.696 PSIA

Compressibility

25 deg C

14.696 PSIA

Gas Viscosities, Densities and Compressibilities at 25o C

Gas

Number

0 Air Air 172.588 1.2927 0.9994

1 Ar Argon 209.566 1.7840 0.9991

2 CH4 Methane 103.657 0.7175 0.9976

3 CO Carbon Monoxide 165.130 1.2505 0.9994

4 CO2 Carbon Dioxide 137.129 1.9768 0.9933

5 C2H6 Ethane 86.127 1.3551 0.9900

6 H2 Hydrogen 83.970 0.08988 1.0007

7 He Helium 186.945 0.17849 1.0005

8 N2 Nitrogen 166.371 1.2504 0.9995

9 N2O Nitrous Oxide 136.350 1.9778 0.9928 10 Ne Neon 293.825 0.8999 1.0005 11 O2 Oxygen 190.555 1.4290 0.9990 12 C3H8 Propane 74.687 2.0101 0.9787 13 n-C4H10 normal-Butane 67.691 2.7048 0.9587 14 C2H2 Acetylene 97.374 1.1728 0.9905 15 C2H4 Ethylene 94.690 1.2611 0.9925 16 i-C4H10 iso-Butane 68.759 2.6893 0.9627 17 Kr Krypton 232.175 3.7422 0.9991 18 Xe Xenon 212.085 5.8988 0.9931 19 SF6 Sulfur Hexauoride 140.890 6.6154 0.9850 20 C-25 75% Argon / 25% CO2 190.579 1.8309 0.9982 21 C-10 90% Argon / 10% CO2 201.897 1.8027 0.9987 22 C-8 92% Argon / 8% CO2 203.423 1.7989 0.9988 23 C-2 98% Argon / 2% CO2 208.022 1.7877 0.9990 24 C-75 75% CO2 / 25% Argon 154.328 1.9270 0.9954 25 A-75 75% Argon / 25% Helium 214.808 1.3821 0.9995 26 A-25 75% Helium / 25% Argon 218.962 0.5794 1.0002

27 A1025

28 Star29

29 P-5 95% Argon / 5% Methane 207.633 1.7307 0.9990

*in micropoise (1 Poise = gram / (cm) (sec)) ** Grams/Liter (NIST REFPROP 7 database)

Short Form Long Form

90% Helium / 7.5% Argon

/ 2.5% CO2

(Praxair - Helistar® A1025)

90% Argon / 8% CO2

/ 2% Oxygen

(Praxair - Stargon® CS)

Viscosity*

0 deg C

14.696 PSIA

201.284 0.3434 1.0002

203.139 1.7918 0.9988

Density**

0 deg C

14.696 PSIA

Compressibility

0 deg C

14.696 PSIA

Gas Viscosities, Densities and Compressibilities at 0o C

Volumetric Flow Meters Under Pressure

V Series Volumetric Flow Meters 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 quantied 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 dened as:

Re = ρVL/η

Where: ρ = density V = 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.

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 difcult 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.

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 high-

pressure 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 specied limits will return the unit to normal operation and accuracy.

Meter reads negative ow when there is a conrmed no ow condition.

This is an indication of an improper tare. If the meter is tared while there is ow, that ow is accepted as zero ow. When an actual zero ow condition exists, the meter will read a negative ow. Simply re-tare at the conrmed zero ow condition. Also note that while the meter is intended for positive ow, it will read negative ow with reasonable accuracy (it is not calibrated for bi-directional ow) and no damage

will result.

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 specied set of standard conditions. The calibration sheet provided with each meter lists its

standard conditions.

Flow utters or is jumpy.

The meters are very fast and will pick up any actual ow uctuations such as from a diaphragm pump, etc. Also, inspect the inside of the upstream connection for debris such a Teon tape shreds. Note: M & V Series meters feature a programmable geometric running average (GRA) that can aid in allowing a rapidly uctuating ow to be read.

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 meter reading is strange, inconsistent, or incorrect.

Make sure you use a volumetric ow meter only under low pressure (close to atmospheric) and with

little to no back pressure for accurate readings. Mass meters should be used for higher pressure

applications. See page 26.

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. Conrm 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 specied.

M or V Series meters 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.

M or V Series meters 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 24.

Maintenance and Recalibration

General: M or V Series Flow Meters 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 meter is designed to measure CLEAN, DRY, NON-CORROSIVE gases. A 20 micron lter (50 micron for 50 LPM and up) mounted upstream of the meter 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 sufcient. 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 14).

Cleaning: M or V Series Flow Meters require no periodic cleaning. If necessary, the outside of the meter

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

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.

Technical Data for Micro Flow Mass & Volumetric Flow Meters

0-0.5SCCM Full Scale up to 0-50SCCM Full Scale

Specication Mass Meter Volumetric Meter Description

Accuracy ± 0.8% of Reading ±0.2% of Full Scale

High Accuracy Option ± 0.4% of Reading ±0.2% of Full Scale

Repeatability ± 0.2% Full Scale

Operating Range

Typical Response Time

Standard Conditions (STP) 25ºC & 14.696PSIA Not Applicable Mass Reference Conditions

Operating Temperature

Zero Shift 0.02% Full Scale / ºCelsius / Atm

Span Shift 0.02% Full Scale / ºCelsius / Atm

Humidity Range 0 to 100% Non–Condensing

Measurable Flow Rate

Maximum Pressure

Input /Output Signal Digital

Input / Output Signal Analog Mass Flow Volumetric Flow 0-5Vdc

Optional Input / Output

Signal Secondary Analog

Electrical Connections 8 Pin

Supply Voltage 7 to 30 Vdc (15-30Vdc for 4-20mA outputs) Supply Current 0.035Amp (+ output current on 4-20mA)

Mounting Attitude Sensitivity 0% Tare after installation

Warm-up Time

Wetted Materials

* Volumetric meters only: Operating pressure limitations determined by Reynolds number thresholds. For operating pressures >10PSIG, please contact the manufacturer for more details.

Mass, Volume, Pressure

& Temperature

Mass, Volume, Pressure

or Temperature

303 & 302 Stainless Steel, Viton®, Silicon, RTV, Glass Reinforced Nylon,

Aluminum, Buna-N.

1% to 100% Full Scale Measure

10 Milliseconds (Adjustable)

−10 to +50 ºCelsius

128% Full Scale

125 125* PSIG

Volumetric Flow RS-232 Serial

Volumetric Flow

< 1 Second

At calibration conditions after tare

0-5 Vdc or 0-10Vdc or 4-

20mA Mini-DIN

Mechanical Specications

Full Scale Flow

Mass Meter

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 Meter

0.5CCM up to

1CCM

2CCM up to

50CCM

Mechanical

Dimensions

3.9”H x 2.4”W x 1.1”D

Process

Connections

10-32 Female

Thread*

Pressure Drop2

(PSID)

0.5

1.0

Dimensional Drawings: page 33

Technical Data for Low Flow Mass & Volumetric Flow Meters

>50SCCM Full Scale up to 0-20SLPM Full Scale

Specication Mass Meter Volumetric Meter Description

Accuracy ± 0.8% of Reading ±0.2% of Full Scale

High Accuracy Option ± 0.4% of Reading ±0.2% of Full Scale

Repeatability ± 0.2% Full Scale

Operating Range

Typical Response Time

1% to 100% Full Scale Measure

10 Milliseconds (Adjustable)

Standard Conditions (STP) 25ºC & 14.696PSIA Not Applicable Mass Reference Conditions

Operating Temperature

−10 to +50 ºCelsius

Zero Shift 0.02% Full Scale / ºCelsius / Atm

Span Shift 0.02% Full Scale / ºCelsius / Atm

Humidity Range 0 to 100% Non–Condensing

Measurable Flow Rate

Maximum Pressure

Input /Output Signal Digital

125 125* PSIG

Mass, Volume, Pressure

& Temperature

128% Full Scale

Volumetric Flow RS-232 Serial

Input / Output Signal Analog Mass Flow Volumetric Flow 0-5Vdc

Optional Input / Output

Signal Secondary Analog

Mass, Volume, Pressure

or Temperature

Volumetric Flow

Electrical Connections 8 Pin

Supply Voltage 7 to 30 Vdc (15-30Vdc for 4-20mA outputs) Supply Current 0.035Amp (+ output current on 4-20mA)

Mounting Attitude Sensitivity 0% Tare after installation

Warm-up Time

Wetted Materials

303 & 302 Stainless Steel, Viton®, Silicon, RTV, Glass Reinforced Nylon,

Aluminum.

< 1 Second

* 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

0-5 Vdc or 0-10Vdc or 4-

20mA Mini-DIN

Mechanical Specications

Full Scale Flow

Mass Meter

>50SCCM to

10SLPM

>50SCCM to

20SLPM

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 Meter

>50CCM to 10LPM 4.1”H x 2.4”W x 1.1”D 1/8” NPT Female

>50CCM to 20LPM 4.2”H x 2.4”W x 1.1”D 1/8” NPT Female

Mechanical

Dimensions

Process

Connections

Pressure Drop2

(PSID)

1.0

Dimensional Drawings: page 33, 34

Technical Data for Moderate Flow Mass & Volumetric Flow Meters

>20SLPM Full Scale up to 0-250SLPM Full Scale

Specication Mass Meter Volumetric Meter Description

Accuracy ± 0.8% of Reading ±0.2% of Full Scale

High Accuracy Option ± 0.4% of Reading ±0.2% of Full Scale

Repeatability ± 0.2% Full Scale

Operating Range

Typical Response Time

1% to 100% Full Scale Measure

10 Milliseconds (Adjustable)

Standard Conditions (STP) 25ºC & 14.696PSIA Not Applicable Mass Reference Conditions

Operating Temperature

−10 to +50 ºCelsius

Zero Shift 0.02% Full Scale / ºCelsius / Atm

Span Shift 0.02% Full Scale / ºCelsius / Atm

Humidity Range 0 to 100% Non–Condensing

Measurable Flow Rate

Maximum Pressure

Input /Output Signal Digital

125 125* PSIG

Mass, Volume, Pressure

& Temperature

128% Full Scale

Volumetric Flow RS-232 Serial

Input / Output Signal Analog Mass Flow Volumetric Flow 0-5Vdc

Optional Input / Output

Signal Secondary Analog

Mass, Volume, Pressure

or Temperature

Volumetric Flow

Electrical Connections 8 Pin

Supply Voltage 7 to 30 Vdc (15-30Vdc for 4-20mA outputs) Supply Current 0.035Amp (+ output current on 4-20mA)

Mounting Attitude Sensitivity 0% Tare after installation

Warm-up Time

Wetted Materials

303 & 302 Stainless Steel, Viton®, Silicon, RTV, Glass Reinforced Nylon,

Aluminum.

< 1 Second

* 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

0-5 Vdc or 0-10Vdc or 4-

20mA Mini-DIN

Mechanical Specications

Full Scale Flow

Mass Meter

>20 to 100SLPM >20 to 100SLPM 4.4”H x 4.0”W x 1.1”D 1/4” NPT Female

>50SCCM to

20SLPM

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 Meter

>50CCM to 20LPM 5.0”H x 4.0”W x 1.6”D 1/2” NPT Female

Mechanical

Dimensions

Process

Connections

(PSID)

1.0

1.7

Pressure Drop2

Dimensional Drawings: page 34, 35

Technical Data for High Flow Mass & Volumetric Flow Meters

>250 SLPM Full Scale up to 0-1500 SLPM Full Scale

Specication Mass Meter Volumetric Meter Description

Accuracy ± 0.8% of Reading ±0.2% of Full Scale

High Accuracy Option ± 0.4% of Reading ±0.2% of Full Scale

Repeatability ± 0.2% Full Scale

Operating Range

Typical Response Time

Standard Conditions (STP) 25ºC & 14.696PSIA Not Applicable Mass Reference Conditions

Operating Temperature

Zero Shift 0.02% Full Scale / ºCelsius / Atm

Span Shift 0.02% Full Scale / ºCelsius / Atm

Humidity Range 0 to 100% Non–Condensing

Measurable Flow Rate

Maximum Pressure

Input /Output Signal Digital

Input / Output Signal Analog Mass Flow Volumetric Flow 0-5Vdc

Optional Input / Output

Signal Secondary Analog

Electrical Connections 8 Pin

Supply Voltage 7 to 30 Vdc (15-30Vdc for 4-20mA outputs) Supply Current 0.035Amp (+ output current on 4-20mA)

Mounting Attitude Sensitivity 0% Tare after installation

Warm-up Time

Wetted Materials

* Volumetric meters only: Operating pressure limitations determined by Reynolds number thresholds. For operating pressures >10PSIG, please contact the manufacturer for more details.

Mass, Volume, Pressure

& Temperature

Mass, Volume, Pressure

or Temperature

303 & 302 Stainless Steel, Viton®, Silicon, RTV, Glass Reinforced Nylon,

Aluminum.

1% to 100% Full Scale Measure

10 Milliseconds (Adjustable)

−10 to +50 ºCelsius

128% Full Scale

125 125* PSIG

Volumetric Flow RS-232 Serial

Volumetric Flow

< 1 Second

At calibration conditions after tare

0-5 Vdc or 0-10Vdc or 4-

20mA Mini-DIN

Mechanical Specications

Full Scale Flow

Mass Meter

>250SLPM >250LPM 1000SLPM 1000LPM 6.8 1500SLPM 1500LPM 12.0

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 Meter

Mechanical

Dimensions

5.0”H x 4.0”W x 1.6”D 3/4” NPT Female

Process

Connections

Pressure Drop2

(PSID)

2.5

Dimensional Drawings: page 35

343536

Option: Totalizing Mode

M or V 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 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 specied on a meter which is totalizing in liters, the maximum count would be

9999.99 liters. If the same unit were specied 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 specied:

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 Notication – When the counter reaches the maximum count it automatically rolls over to zero, displays an overow 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 side 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>)

Option: 9 Volt Battery Pack

A Battery Pack that uses a common 9 Volt battery can be mounted to the top of your M or V Series Flow Meter. Power is passed from the battery to the ow meter through the 8 pin Mini-DIN connector. Output signals from the ow meter or pressure guage are passed through the male connector on the bottom

of the battery pack to the female connector on top of the battery pack so the signals can be accessed

normally. Turn off the switch on top of the battery pack when the meter is not in use. (Note: The Battery Pack cannot be used with Flow Controllers)

Normal (9V alkaline) battery life is approximately 8 hours (30-40 hours with a 9V-lithium battery), however many factors can affect this. Replace the battery as often as required. A common indicator that the battery

may be approaching the end of its life is a sharp increase in the temperature indicated on the meter. This false signal can result when the voltage drops below its normally regulated level. This can affect the accuracy of the meter so it is good practice to check that the temperature is approximately correct

(25°C is about room temperature) or use a fresh battery especially if the measurement is critical.

Replacing the Battery:

The battery can be replaced with the battery pack installed on the ow meter.

Remove the four Phillips head screws from the back cover and gently remove it as shown below.

Remove the 9V battery, pulling the top of the battery out rst.

2. Remove the old battery from the harness and replace it with a new battery.

3. Install the new battery bottom end rst and replace the back cover so that the cushioning pad

4. presses directly down on the battery. Replace the four Phillips head screws.

Battery Pack Back Cover Removal

Battery Pack Installation and Removal:

The battery must be removed before the battery pack can be installed or removed.

Remove the back cover of the battery pack and remove the battery if installed (see “Replacing the

Battery”). Carefully place the battery pack on top of the ow meter, being especially careful that the pins in the

8 pin Mini-DIN plug are inserted properly into the 8 pin Mini-DIN socket on top of the ow meter. The

two screws trapped in the bottom of the battery pack will not allow the plug to be completely inserted into the socket until they are screwed into place.

Slip the included hex wrench into either of the two holes on the top of the battery pack as shown

below and start the screw into the corresponding threaded hole in the top of the meter. Before the screw is tightened down all the way, move the hex wrench to the other hole and tighten

4. the other screw gently down. Avoid over tightening the screw.

Return the hex wrench to the rst hole and tighten the rst screw gently down. Avoid over tightening

the screw. Install the battery and replace the back cover as described above.

6. Removal is the reverse of the installation.

Wrench Access Hole

3/32 Hex Wrench

9 volt

battery

Trapped Mounting ScrewTrapped Mounting Screw

8 Pin Mini DIN Plug

Back of

Meter

Battery Pack Installation/Removal

Accessories

Battery Pack

Muti-Drop Box

8 Pin Male Mini-DIN connector cable, single ended, 6 foot length

8 Pin Male Mini-DIN connector cable, double ended, 6 foot length

8 Pin Male Mini-DIN connector cable, single ended, 25 foot length

8 Pin Male Right Angle Mini-Din Cable, single ended, 6 foot length

8 Pin Male Mini-DIN to DB9 Female Adaptor 6 foot length

AC to DC 12 Volt Power Supply Adapter

AC to DC 24 Volt Power Supply Adapter

AC to DC 12 Volt European Power Supply Adapter

AC to DC 24 Volt European Power Supply Adapter

Industrial cable, 6 Pin, single ended, 10 foot length

Flow Conversion Table:

CCM CCH LPM LPH CFM CFH

CFH 0.0021 0.00003 2.1189 0.035 60.0 1.0

CFM 0.000035 0.0000005 0.035 0.00059 1.0 0.0166

LPH 0.06 0.001 60.0 1.0 1699.0 28.316

LPM 0.001 0.000017 1.0 0.0166 28.316 0.4719

CCH 60.0 1.0 60000.0 1000.0 1699011.0 28317.0

CCM 1.0 0.0167 1000.0 16.667 28317.0 471.947

Serial Number: ____________________________

Model Number: ____________________________

Calibration Certicate

(Store device calibration certicate in the pocket below.)

Apex Digital Precision Gas Flow Meter User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual