Your DMF Mass Flow Controller was carefully packed in a sturdy cardboard carton, with anti-static cushioning materials to withstand shipping shock. Upon
receipt, inspect the package for possible external damage. In case of external
damage to the package contact the shipping company immediately.
1.2 Unpack the Mass Flow Controller
Open the carton carefully from the top and inspect for any sign of concealed shipping damage. In addition to contacting the shipping carrier please forward a copy
of any damage report to your distributor or Dwyer directly.
When unpacking the instrument please make sure that you hav e all the items indicated on the Packing List.Please report any shortages promptly.
1.3Returning Merchandise for Repair
Please contact the customer service representative of your distributor or Dwyer if
you purchased your Mass Flow Controller directly, and request a Return
Authorization Number (RAN). Equipment returned without an RAN will not
be accepted. Dwyer reserves the right to charge a fee to the customer for equip-
ment returned under warranty claims if the instruments are tested to be free from
warrantied defects.
Shipping charges are borne by the customer.Meters returned "collect" will not be
accepted!
It is mandatory that any equipment returned for servicing be purged and neutralized of any dangerous contents including but not limited to toxic, bacterially infectious, corrosive or radioactive substances. No work shall be performed on a
returned product unless the customer submits a fully executed, signed SAFETY
CERTIFICATE. Please request form from the Service Manager.
2. INSTALLATION
2.1Primary Gas Connections
Please note that the DMF Mass Flow Controller will not operate with liquids.Only
clean gases are allowed to be introduced into the instrument. If gases are contaminated they must be filtered to prev ent the introduction of impediments into the
sensor.
Caution: DMF transducers should not be used for monitoring
OXYGEN gas unless specifically cleaned and prepared for such
application. For more information, contact your distributor or Dwyer.
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Attitude sensitivity of the Mass Flow Controller is +15F. This means that the gas flow
path of the Flow Controller must be horizontal within those stated limits. Should
there be need for a different orientation of the meter, re-calibration may be necessary.It is also preferable to install the DMF transducer in a stable environment, free
of frequent and sudden temperature changes, high moisture, and drafts.
Prior to connecting gas lines inspect all parts of the piping system including ferrules and fittings for dust or other contaminants.
Be sure to observe the direction of gas flow as indicated by the arrow on the front
of the meter when connecting the gas system to be monitored.
Insert tubing into the compression fittings until the ends of the properly sized tubings home flush against the shoulders of the fittings. Compression fittings are to
be tightened according to the manufacturer's instructions to one and one quarter
turns. Avoid over tightening which will seriously damage the Restrictor Flow
Elements (RFE's)!
DMF transducers are supplied with standard 1/4 inch (DMF 41401-41433) or 3/8
inch (DMF 41842), or optional 1/8 inch inlet and outlet compression fittings which
should not be removed unless the meter is being cleaned or calibrated for a new
flow range.
Using a Helium Leak Detector or other equivalent method perform a thorough
leak test of the entire system.
age within stated limits. See specifications in this manual.)
(All DMF's are checked prior to shipment for leak-
2.2 Electrical Connections
DMF transducers require a +15VDC and -15VDC power supply to operate.
Additionally, a readout panel meter, digital multimeter, or other equivalent device
is required to observe the flow signal in analog mode. A variable analog 0-5VDC
reference input is required for DMF models to operate in analog mode. The Dwyer
SDPROC accessory Command Modules offer a convenient and compact means
to fulfill these needs.
DMF is supplied with a 25 pin "D" connector. Pin diagram is presented in figure b-2.
2.3 Communication Parameters and Connections
Baud rate: 9600 baudStop bit:1
Data bits:8Parity:NON
RS-232 option: Crossover connection has to be established:
Pin 11 (TX) of the “D” connector has to be connected to RX
(pin 2 on the DB9 connector).
Pin 24 (RX) of the “D” connector has to be connected to TX
(pin 3 on the DB9 connector).
Pin 20 (Common) of the “D” connector has to be connected
to GND (pin 5 on the DB9 connector).
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Page 6
RS-485 option:
The RS485 converter/adapter has to be configured for:multidrop, 2 wire, half duplex
mode.The transmitter circuit has to be enabled by TD or RTS (depending on which
is available on the con v erter/adapter).Settings for the receiver circuit usually should
follow the selection made for the transmitter circuit in order to eliminate Echo.
Pin 11 (-) of the “D” connector has to be connected to
T- or R- on the RS-485 converter/adapter.
Pin 24 (+) of the “D” connector has to be connected to
T+ or R+ on the RS-485 converter/adapter.
Pin 20 (Common) of the “D” connector has to be connected
to GND on the RS-485 converter/adapter.
3
Page 7
FIGURE b-1, WIRING DIAGRAM FOR DMF TRANSDUCERS.
4
Page 8
PIN FUNCTION
1+15 VDC Power Supply
2 0-5 VDC Flow Signal (4-20mA Option)
3 0-5 VDC Set Point Input (4-20mA Option)
4 Force Valve Open Control
5 Force Valve Closed Control
6 (Reserved)
7 (Reserved)
8 Relay No. 1 - Common Contact
9 Relay No. 1 - Nor mally Open Contact
10 Relay No.2 - Normally Closed Contact
11 RS485 (-) (Optional RS232 TX)
12 (No Connection)
13 Chassis Ground
14 -15 VDC Power Supply
15 Common, Signal Ground For Pin 2
16 Common, Signal Ground For Pin 3
17 (Optional) RS232 Common
18 Common, Power Supply
19 Common
20 Common
21 Relay No.1 - Normally Closed Contact
22 Relay No.2 - Common Contact
23 Relay No.2 - Normally Open Contact
24 RS485 (+) (Optional RS232 RX)
25 Return for Pin 2 (Optional 4-20 mA Only)
In general, "D" Connector numbering patterns are standardized.There are, however , some connectors with nonconf orming patterns and the numbering sequence
on your mating connector may or may not coincide with the numbering sequence
shown in our pin configuration table above. It is imperative that you match the
appropriate wires in accordance with the correct sequence regardless of the particular numbers displayed on your mating connector.
Make sure power is OFF when connecting or disconnecting any cab les in the system.
The (+) and (-) power inputs are each protected by a 500mA M (medium time-lag)
resettable fuse. If a shorting condition or polarity reversal occurs, the fuse will cut
power to the flow transducer circuit. Disconnect the power to the unit, remove the
faulty condition, and reconnect the power. The fuse will reset once the faulty condition has been removed.
Cable length may not exceed 9.5 feet (3 meters).
5
Page 9
Use of the DMF flow transducer in a manner other than that specified in this man-
F
ual or in writing from Dwyer, ma y impair the protection provided b y the equipment.
3. PRINCIPLE OF OPERATION
The stream of gas entering the Mass Flow transducer is split by shunting a small
portion of the flow through a capillary stainless steel sensor tube. The remainder
of the gas flows through the primary flow conduit. The geometr y of the primary
conduit and the sensor tube are designed to ensure laminar flow in each branch.
According to principles of fluid dynamics the flow rates of a gas in the two laminar flow conduits are proportional to one another.Therefore, the flow rates measured in the sensor tube are directly proportional to the total flow through the transducer.
In order to sense the flow in the sensor tube, heat flux is introduced at two sections of the sensor tube by means of precision wound heater sensor coils.Heat is
transferred through the thin wall of the sensor tube to the gas flowing inside. As
gas flow takes place heat is carried by the gas stream from the upstream coil to
the downstream coil windings. The resultant temperature dependent resistance
differential is detected by the electronic control circuit.The measured gradient at
the sensor windings is linearly proportional to the instantaneous rate of flow taking place.
An output signal is generated that is a function of the amount of heat carried by
the gases to indicate mass molecular based flow rates.
Additionally , DMF model Mass Flo w Controllers incorporate a microprocessor and
non-volatile memory that stores all calibration factors and directly controls a proportionating solenoid valve. The digital closed loop control system of the DMF
continuously compares the mass flow output with the selected flow rate.
Deviations from the set point are corrected by compensating valve adjustments,
thus maintaining the desired flow parameters with a high degree of accuracy.
4.SPECIFICATIONS
FLOW MEDIUM:Please note that DMF Mass Flow Controllers are
designed to work with clean gases only. Never try to
meter or control flow rates of liquids with any DMF.
CALIBRATIONS:Performed at standard conditions [14.7 psia
(1.01 bars) and 70
requested or stated.
ENVIRONMENTAL (PER IEC 664):
Installation Level II;Pollution Degree II.
F (21.1FC)] unless otherwise
6
Page 10
4.1DMF Mass Flow Controllers
F
F
F
ACCURACY: +
59
F to 77FF (15FC to 25FC) and pressures of 10 to 60 psia (0.7 to 4.1 bars).
REPEATABILITY: +
TEMPERATURE COEFFICIENT: 0.1% of full scale/
1% of full scale, including linearity for gas temperatures ranging from
0.15% of full scale.
C.
PRESSURE COEFFICIENT: 0.01% of full scale/psi (0.07 bar).
RESPONSE TIME: DMF 41401-41411: 300ms time constant; approximately 1
second to within +
2% of set flow rate for 25% to 100% of full scale flow.
DMF41431-41842: 600ms time constant; approximately 2
seconds to within +
2% of set flow rate for 25% to 100% of full scale flow.
GAS PRESSURE: 500 psig (34.5 bars) maximum; optimum pressure is 20 psig (1.4
bars); 25 psig (1.7 bars gauge) for DMF 41842.
DIFFERENTIAL PRESSURES REQUIRED: 5 to 50 psig (0.35 to 3.34 bars) differential
pressures. Optimum differential pressure is 25 psid (1.7 bars). See Table IV for
pressure drops associated with various models and flow rates.
MAXIMUM PRESSURE DIFFERENTIAL: 50 psid for DMF 41401-41433, 40 psid for
DMF 41842.
GAS AND AMBIENT TEMPERATURE: 41
F to 122FF (5FC to 50FC).
RELATIVE GAS HUMIDITY: Up to 70%.
LEAK INTEGRITY: 1 x 10
-9
sccs He maximum to the outside environment.
ATTITUDE SENSITIVITY: 1% shift for a 90 degree rotation from horizontal to vertical; standard calibration is in horizontal position.
OUTPUT SIGNALS: Linear 0-5 VDC (2000 : minimum load impedance); 4-20 mA
optional (50-500 :loop resistance); 20 mV peak to peak max noise.
Contact your distributor or Dwyer for optional RS232 or IEEE488 interfaces.
5% VDC, 450 mA max; 6.75 watts max; Power inputs are each pro-
5% VDC, 450 mA max, 6.75 watts
tected by a 500mA M (medium time-lag) resettable fuse, and an inverse shunt
rectifier diode for polarity protection.
WETTED MATERIALS: 316 stainless steel, 416 stainless steel, VITON7 O-rings;
BUNA-N7, NEOPRENE7 or KALREZ7 O-rings are optional.
7
Page 11
Dwyer makes no expressed or implied guarantees of corrosion resistance of
mass flow meters as pertains to different flow media reacting with components of
meters. It is the customers' sole responsibility to select the model suitable for a
particular gas based on the fluid contacting (wetted) materials offered in the different models.
INLET AND OUTLET CONNECTIONS: 1/4" (DMF 41401-41433) (DMF 41842) or 3/8"
compression fittings standard; 1/8" or 3/8" compression fittings and 1/4" VCR7 fit-
tings are optional.
TRANSDUCER INTERFACE CABLE:Flat cable with 25-pin "D" connectors on the
ends is standard.Optional shielded cable is available with male/female 25-pin "D"
connector ends. [Cable length may not exceed 9.5 feet (3 meters)]
4.2 CE Compliance
Any model DMF bearing a CE marking on it, is in compliance with the below
stated test standards currently accepted.
EMC Compliance with 89/336/EEC as amended;
Emission Standard: EN 55011:1991, Group 1, Class A
Immunity Standard: EN 55082-1:1992
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Page 12
FLOW RANGES
TABLE I DMF 41 LOW FLOW MASS FLOW CONTROLLERS*
CODE
4010 to 10070 to 1
4020 to 20080 to 2
4030 to 50090 to 5
4040 to 100100 to 10
4050 to 200
4060 to 500
scc/min [N2]
CODE
std liters/min [N
TABLE II DMF 36 MEDIUM FLOW MASS FLOW CONTROLLERS*
CODEstandard liters/min [N2]
110 to 15
3020
3130
3240
3350
]
2
TABLE III DMF 46 HIGH FLOW MASS FLOW CONTROLLERS*
CODEstandard liters/min [N2]
4060
4180
42100
* Flow rates are stated for Nitrogen at STP conditions [i.e. 70FF (21.1FC) at 1 atm].
For other gases use the K factor as a multiplier from APPENDIX 2.
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Page 13
TABLE IV PRESSURE DROPS
MODEL
DMF 41411up to 107201.0675
DMF 41431
DMF 41433 5054408.00551
DMF 418421001285018.891302
FLOW RATE
[std liters/min]
1526303.87266
3023803.50241
MAXIMUM PRESSURE DROP
[mm H2O][psid][mbar]
TABLE V APPROXIMATE WEIGHTS
MODELWEIGHTSHIPPING WEIGHT
DMF 41401-41411 controller2.20 lbs (1.00 kg)3.70 lbs (1.68 kg)
DMF 41431-41842 controller2.84 lbs (1.29 kg)4.34 lbs (1.97 kg)
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Page 14
5. OPERATING INSTRUCTIONS
5.1 Preparation and Warm Up
It is assumed that the Mass Flow Controller or Controller has been correctly
installed and thoroughly leak tested as described in section (2). Make sure the
flow source is OFF. Power up the transducer using your own power supply (or
switch the POWER switch to the ON position at the front panel of your SDPROC
Command Module). Allow the Mass Flow Meter or Controller to warm-up for a
minimum of 15 minutes.
During initial powering of the DMF transducer, the flow output signal will be indicating a higher than usual output. This is indication that the DMF transducer has
not yet attained it's minimum operating temperature. This condition will automatically cancel within a few minutes and the transducer should eventually zero.
Caution: If the valve is left in the AUTO (control) or OPEN mode for an
extended period of time, it may become warm or even hot to the touch.
Use care in avoiding direct contact with the valve during operation.
5.2 Flow Signal Output Readings
The flow signal output can be viewed on the panel meter, digital multimeter, or
other display device used as shown in figure b-1.
When using the accessory SDPROC Command Module the flow rate will appear
on the display at the front panel.The obser ved reading is a 0 to 100% indication
(direct engineering units are optional). [If using a multichannel readout, be sure
that the CHANNEL selector switch is set to the correct channel.]
Analog output flow signals of 0 to 5 VDC or optional 4 to 20 mA are attained at
the appropriate pins the 25-pin "D" connector (see Figure b-2) on the side of the
DMF transducer.The output flow signal is also a v ailab le at the DATA connector on
the rear panel of the SDPROC Command Module.
Meter signal output is linearly proportional to the mass molecular flow rate of the
gas being metered. The full scale range and gas for which your meter has been
calibrated are shown on the flow transducer's front label.
For information on the RS485 or optional RS232 interfaces please contact your
distributor or Dwyer.
5.3 Swamping Condition
If a flow of more than 10% above the maximum flow rate of the Mass Flow
Controller is taking place, a condition known as "swamping" may occur.Readings
of a "swamped" meter cannot be assumed to be either accurate or linear. Flow
must be restored to below 110% of maximum meter range. Once flow rates are
lowered to within calibrated range, the swamping condition will end. Operation of
the meter above 110% of maximum calibrated flow may increase recovery time.
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Page 15
5.4 Set Point Reference Signal
DMF flow controllers have a built-in solenoid valve and allow the user to set the
flow to any desired flow rate within the range of the particular model installed.This
valve is normally closed when no power is applied.
The set point input in analog mode responds to an analog 0 to 5 VDC reference
voltage or 4-20mA reference current.This voltage is a linear representation of 0
to 100% of the full scale mass flow rate.Response time to set point changes are
1 second to within 2% of the final flow over 25 to 100% of full scale.
A variable 0 to 5VDC analog signal may be applied directly to the SET POINT and
COMMON connections of the DMF transducer (see Figure b-1).
If a potentiometer is used to adjust the set point reference signal its value should
be between 5K to 100K ohm and it should be capable of at least 10-turns or more
for adjustment.
5.5 Valve OFF Control
It may, at times, be desirable to set the flow and maintain that setting while being
able to turn the flow control valve off and on again.This can be accomplished via
pin 5 on the 25-pin "D" connector.When 0 VDC (LO W) signal is applied (connection
via a relay, switch or NPN open collector transistor is permissible), the solenoid
valve is not powered and therefore will remain normally closed. Conversely, when
the pin is disconnected from 0 VDC ("floating”) the solenoid v alv e will remain activ e .
The simplest means for utilizing the VALVE OFF control feature, is to connect a
toggle switch between the COMMON and FORCE VALVE CLOSED pins of the
DMF transducer.Toggling the switch on and off will allow for activating and deactivating the solenoid valve.
5.6 Valve Open /Purge
At times, it may be necessary to purge the flow system with a neutralizing gas
such as pure dry nitrogen.The DMF transducer is capable of a full open condition
for the solenoid valve, regardless of set point conditions. Connecting the FORCE
VALVE OPEN pin (pin 4 on 25-pin "D" connector) to ground will fully open the
valve. This connection can be made with a relay, switch or NPN open collector
transistor. Conversely, when the pin is disconnected from 0 VDC ("floating”) the
solenoid valve will remain active. (Note: in digital mode hardware I/O overrides
software command)
The simplest means for utilizing the V ALVE OPEN control f eature, is to connect a toggle switch between the COMMON and FORCE VALVE OPEN pins of the DMF transducer.Toggling the switch on will cause the v alv e to open fully and purge the system.
Toggling the switch off will allow the solenoid valve to resume normal activity.
Caution: If the valve is left in the AUTO (control) or OPEN mode for an
extended period of time, it may become warm or even hot to the touch.
Use care in avoiding direct contact with the valve during operation.
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5.7 Analog Interface Configuration
The DMF can be configured for the desired range and scaling by selection of
analog board (see APPENDIX 1 on page 21) jumpers as follows:
0 to 5 V output:Jumper pins 2 and 3 of JP6.
Jumper pins 2 and 3 of JP3.
Jumper pins 2 and 3 of JP5.
Jumper pins 1 and 2 of JP12.
0 to 5 V input:Jumper pins 2 and 3 of JP2.
Jumper pins 2 and 3 of JP4.
Jumper pins 1 and 2 of JP11.
0 to 10 V output:As for 0 to 5V, but jumper pins 2 and 3 of JP12.
4 to 20 mA output:Jumper pins 1 and 2 of JP6.
Jumper pins 1 and 2 of JP3.
Jumper pins 1 and 2 of JP5.
Jumper pins 1 and 2 of JP12.
4 to 20 mA input:Jumper pins 1 and 2 of JP2.
Jumper pins 1 and 2 of JP4.
Jumper pins 1 and 2 of JP11.
By default the DMF is configured for analog input output ranges set to 0-5V
(unless ordered with special configuration).
6. MAINTENANCE
6.1 Introduction
It is important that the Mass Flow Controller is used with clean, filtered gases only .
Liquids may not be metered. Since the RTD sensor consists, in part, of a small
capillary stainless steel tube, it is prone to occlusion due to impediments or gas
crystallization. Other flow passages are also easily obstructed. Therefore, great
care must be exercised to avoid the introduction of any potential flow impediment.
To protect the instrument a 50 micron (DMF41401-41411) or 60 micron
(DMF41431-41842) filter is built into the inlet of the flow transducer. The filter
screen and the flow paths may require occasional cleaning as described below.
There is no other recommended maintenance required. It is good practice, however, to keep the meter away from vibration, hot or corrosive environments and
excessive RF or magnetic interference.
If periodic calibrations are required they should be performed by qualified personnel and calibrating instruments, as described in section (7). It is recommended that units are returned to Dwyer for repair service and calibration.
CAUTION: TO PROTECT SERVICING PERSONNEL IT IS MANDATORY
THAT ANY INSTRUMENT BEING SERVICED IS COMPLETELY
PURGED AND NEUTRALIZED OF TOXIC, BACTERIOLOGICALLY
INFECTED, CORROSIVE OR RADIOACTIVE CONTENTS.
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Page 17
6.2 Flow Path Cleaning
Before attempting any disassembly of the unit for cleaning, try inspecting the flow
paths by looking into the inlet and outlet ends of the meter for any debris that ma y
be clogging the flow through the meter. Remove debris as necessary. If the flow
path is not unclogged, then proceed with steps below.
Do not attempt to disassemble the sensor. If blockage of the sensor tube is not
alleviated by flushing through with cleaning fluids, please return meter to Dwyer
for servicing.
6.2.1 Restrictor Flow Element (RFE)
The Restrictor Flow Element (RFE) is a precision flow divider inside the transducer, which splits the inlet gas flow by a preset amount to the sensor and main
flow paths.The particular RFE used in a given Mass Flow Controller depends on
the gas and flow range of the instrument.
6.2.2 DMF 41401-41411 models
Unscrew the inlet compression fitting of meter.Note that the Restrictor Flow
Element (RFE) is connected to the inlet fitting.
Carefully disassemble the RFE from the inlet connection. The 50 micron filter
screen will now become visible.Push the screen out through the inlet fitting.Clean
or replace each of the removed parts as necessary. If alcohol is used for cleaning, allow time for drying.
Inspect the flow path inside the transducer for any visible signs of contaminants.
If necessary, flush the flow path through with alcohol. Thoroughly dr y the flow
paths by flowing clean dry gas through.
Carefully re-install the RFE and inlet fitting, avoiding any twisting and deforming
the RFE. Be sure that no dust has collected on the O-ring seal.
Note: Overtightening will deform and render the RFE defective.
It is advisable that at least one calibration point be checked after re installing the
inlet fitting - see section (7).
6.2.3 DMF 41431-41842 models
Unscrew the four socket head cap screws (two 10-24 and two 6-32) at the inlet
side of the meter.This will release the short square block containing the inlet compression fitting.
The 60 micron filter screen will now become visible.Remove the screen.DO NOT
remove the RFE inside the flow transducer! Clean or replace each of the remo v ed
parts as necessary. If alcohol is used for cleaning, allow time for drying.
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Page 18
Inspect the flow path inside the transducer for any visible signs of contaminants.
If necessary, flush the flow path through with alcohol. Thoroughly dr y the flow
paths by flowing clean dry gas through.
Re-install the inlet parts and filter screen. Be sure that no dust has collected on
the O-ring seal.
It is advisable that at least one calibration point be checked after re installing the
inlet fitting - see section (7).
6.2.4 Valve Maintenance (DMF)
The solenoid valve consists of 316 and 416 stainless steel, and VITON7 (or
optional NEOPRENE7 or KALREZ7) O-rings and seals. No regular maintenance
is required except for periodic cleaning.
Various corrosive gases may demand more frequent replacement of VITON7
O- rings and seals inside the valve.Be sure to use an elastomer material, appropriate for your specific gas application. Contact your distributor or Dwyer for
optional sealing materials available.
Set the DMF into PURGE mode, and attempt to flush through with a clean, filtered, and neutral gas such as nitrogen.[Another option for fully opening the valve
is to remove the plastic cap on top of the valve, and turn the set screw counterclockwise until it stops. Set valve for the closed position. Apply an inlet pressure
of 5 psig and atmospheric pressure at the outlet. If a small flow occurs, turn the
set screw on top of the solenoid valve clockwise until the flow through the DMF
just stops.
Note: Removal of the factory installed calibration seals and/or any
adjustments made to the meter, as described in this section, will void
any calibration warranty applicable.
7. CALIBRATION PROCEDURES
7.1 Flow Calibration
Dwyer Instruments' Flow Calibration Laboratory offers professional calibration
support for Mass Flow Meters and Controllers, using precision calibrators under
strictly controlled conditions. NIST traceable calibrations are available.
Calibrations can also be performed at customers' site using available standards.
Factory calibrations are performed using NIST traceable precision volumetric calibrators incorporating liquid sealed frictionless actuators.
Generally, calibrations are performed using dry nitrogen gas. The calibration can
then be corrected to the appropriate gas desired based on relative correction [K]
factors shown in the gas fa ctor table see Appendix 2.A reference gas, other than
nitrogen, may be used to closer approximate the flow characteristics of cer tain
gases. This practice is recommended when a reference gas is found with thermodynamic properties similar to the actual gas under consideration. The appro-
15
Page 19
priate relative correction factor should be recalculated see section (9).
It is standard practice to calibrate Mass Flow Meters/Controllers with dry nitrogen
gas at 70FF (21.1EC), 20 psig (1.4 bars) [25 psig (1.7 bars) for DMF 41842] inlet
pressure and 0 psig (0 bar) outlet pressure. It is best to calibrate the DMF transducers to actual operating conditions. Specific gas calibrations of non-toxic and
non-corrosive gases are available at specific conditions. Please contact your distributor or Dwyer for a price quotation.
It is recommended that a flow calibrator of at least four times better collectiv e accuracy than that of the Mass Flow Controller to be calibrated be used. Equipment
required for calibration includes a flow calibration standard and a certified high
sensitivity multimeter (which together have a collective accuracy of +
ter), an insulated (plastic) screwdriver, a flow regulator (example: metering needle
valve) installed upstream from the Mass Flow Controller and a pressure regulated
source of dry filtered nitrogen gas (or other suitable reference gas).
The gas and ambient temperature, as well as inlet and outlet pressure conditions
should be set up in accordance with actual operating conditions.
7.2 Calibration of DMF Mass Flow Controllers
All adjustments to the DMF calibration and control loop tuning are accomplished
using the RS485 (or optional RS232) interface in conjunction with setup and calibration software available from Dwyer. The sensor zero is automatically adjusted internally whenever the control valve is fully closed (set point less than 2% of
full scale) and the unit is warmed up.
0.25% or bet-
DMF Mass Flow Meters may be field recalibrated/checked using the setup and
calibration program for the same range they were originally factory calibrated for.
Flow range changes may require a different Restrictor Flow Element (RFE).
Additionally, a different Solenoid Valve Orifice for the DMF Mass Flow Controller
(see Table VI) may also be required. Consult your distributor or Dwyer for more
information.
TABLE VI DMF SOLENOID VALVE ORIFICE SELECTION TABLE
ORIFICE PART NUMBERFLOW RATE [N2]
OR.010
OR.020
OR.0401 to 5 slpm
OR.0555 to 10 slpm
OR.06310 to 15 slpm
OR.07315 to 20 slpm
OR.09420 to 50 slpm
OR.12550 to 100 slpm
Under 10 sccm
10 to 1000 sccm
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Page 20
8. TROUBLESHOOTING
8.1 Common Conditions
Your Mass Flow Controller was thoroughly checked at numerous quality control
points during and after manufacturing and assembly operations.It was calibrated in accordance to your desired flow and pressure conditions for a given gas or
a mixture of gases.
It was carefully packed to prevent damage during shipment. Should you feel that
the instrument is not functioning properly please check for the following common
conditions first:
Are all cables connected correctly?
Are there any leaks in the installation?
Is the power supply correctly selected according to requirements? When several
meters are used a power supply with appropriate current rating should be selected.
Were the connector pinouts matched properly? When interchanging with other
manufacturers' equipment, cables and connectors must be carefully wired for correct pin configurations.
Is the pressure differential across the instrument sufficient?
For best results it is recommended that instruments are returned to the factory
for servicing. See section 1.3 for return procedures.
8.2 Technical Assistance
Dwyer Instruments will provide technical assistance over the phone to qualified
repair personnel. Please call our Technical Assistance at (219) 879-8000.
Please have your Serial Number and Model Number ready when you call.
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Page 21
8.3Troubleshooting Guide
Indication
lack of
reading
or output
output reads
at (+) or (-)
saturation
only
Likely Reason
power supply off
fuse blown
(DMF)
fuse blown
(SDPROC)
filter screen obstructed at inlet
occluded sensor tube
pc board defect
valve adjustment wrong
fuse blown
(DMF)
Remedy
check connection of power supply
disconnect DMF transducer from
power supply; remove the shorting
condition or check polarities;
fuse resets automatically
disconnect power cord from AC supply; remove and inspect fuses at AC
power input connector of SDPROC;
replace as necessary
REMOVE CAUSE OF SHORT CIRCUIT!
flush clean or disassemble to remove
impediments or replace
flush clean or disassemble to remove
impediments or return to factory for
replacement
return to factory for replacement
re-adjust valve (section 6.2.4)
disconnect DMF transducer from
power supply; remove the shorting
condition or check polarities; fuse
resets automatically
flow reading
does not
coincide with
the set point
(DMF models
only)
no response
to set point
(DMF models
only)
unstable or no
zero reading
inadequate gas pressure
filter screen obstructed at inlet
ground loop
inadequate gas pressure
cable or connector
malfunction
set point is too low
(<2% of full scale)
valve adjustment wrong
gas leak
pc board defective
18
REMOVE CAUSE OF SHORT CIRCUIT!
apply appropriate gas pressure
flush clean or disassemble to remove
impediments or replace
signal and power supply commons are
different
apply appropriate gas pressure
check cables and all connections or
replace
re-adjust set point
re-adjust valve (section 6.2.4)
locate and correct
return to factory for replacement
Page 22
Indication
full scale
output at
"no flow"
condition or
with valve
closed
Likely Reason
defective sensor
gas Leak
Remedy
return to factory for replacement
locate and repair
calibration off
DMF valve
does not work
in open
position
gas metered is not the same
as what meter was calibrated
for
composition of gas changed
gas leak
pc board defective
RFE dirty
occluded sensor tube
filter screen obstructed at inlet
transducer is not mounted
properly
incorrect valve adjustment
pc board defect
cable or connectors
malfunction
use matched calibration
see K factor tables in APPENDIX 2
locate and correct
return to factory for replacement
flush clean or disassemble to remove
impediments
flush clean or disassemble to remove
impediments or return to factory for
replacement
flush clean or disassemble to remove
impediments or replace
check for any tilt or change in the
mounting of the transducer; generally,
units are calibrated for horizontal
installation (relative to the sensor tube)
re-adjust valve (section 6.2.4)
return to factory for replacement
check cable and connectors or replace
DMF valve
does not
work in close
position
differential pressure too high
insufficient inlet pressure
incorrect valve adjustment
pc board defect
cable or connectors
malfunction
orifice obstructed
19
decrease pressure to correct level
adjust appropriately
re-adjust valve (section 6.2.4)
return to factory for replacement
check cable and connectors or replace
disassemble to remove impediments
or return to factory
Page 23
9.CALIBRATION CONVERSIONS FROM REFERENCE
F
GASES
The calibration conversion incorporates the K factor.The K factor is derived from
gas density and coefficient of specific heat. For diatomic gases:
gas
d X C
p
1
=
K
where d = gas density (gram/liter)
C
= coefficient of specific heat (cal/gram)
p
Note in the above relationship that d and Cp are usually chosen at standard conditions of one atmosphere and 25
C.
If the flow range of a Mass Flow Controller or Controller remains unchanged, a
relative K factor is used to relate the calibration of the actual gas to the reference
gas.
Q
a
=
K
Q
r
K
a
=
K
r
where Qa= mass flow rate of an actual gas (sccm)
Q
r
K
a
K
r
= mass flow rate of a reference gas (sccm)
= K factor of an actual gas
= K factor of a reference gas
For example, if we want to know the flow rate of oxygen and wish to calibrate
with nitrogen at 1000 SCCM, the flow rate of oxygen is:
Q
= Qa= Qrx K = 1000 X 0.9926 = 992.6 sccm
O
2
where K = relative K factor to reference gas (oxygen to nitrogen)
NOTES: Dwyer reserves the right to change designs and dimensions at its sole
discretion at any time without notice. For certified dimensions please contact
Dwyer.
29
Page 33
DMF 41431-41842 Mass Flow Controller
NOTES: Dwyer reserves the right to change designs and dimensions at its sole
discretion at any time without notice. For certified dimensions please contact
Dwyer.
30
Page 34
APPENDIX 4
SENDING COMMANDS TO THE DMF
RS485
The standard DMF comes with an RS485 interface. The protocol described below
allows for the unit using either a custom software program or a “dumb terminal”.
All values are sent as printable ASCII characters. The start character is always !and
the command string is terminated with a carriage return (line feeds are
automatically stripped out by the DMF:
!<Addr>, <Cmd>,Arg1,Arg2,Arg3,Arg4<CR>
WHERE:
!Start character
AddrRS485 device address in the ASCII representation of
hexadecimal (00 through FF are valid).**
CmdThe one or two character command from the table above.
Arg1 to Arg4The command arguments from the table above.
Multiple arguments are comma delimited.
CRCarriage return character.
**Default address for all units is 11.
Several examples of commands follow.
All assume that the DMF has been configured for address 15 (0F hex) on the RS485 bus:
1.To put the unit in digital mode:!0F,M,D<CR>
The DMF will reply:!0FMD<CR>
2.To set the flow of 50% of FS:!0F,S,50.0<CR>
The DMF will reply:!0FS50.0<CR>
3.To get a flow reading:!0F,F<CR>
The DMF will reply:!0F50.0<CR>
(Assuming the flow is at 50% FS)
4.Set the high alarm limit to 5% above Set point:!0F,A,H,5.0<CR>
The DMF will reply:!0FA5.0<CR>
31
32
Page 35
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333435
Page 37
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Page 39
36
Page 40
APPENDIX 5
CALIBRATION TABLE: GAS DEPENDENT VARIABLES
INDEX
0BlankSDPROCchar[10] Do not modify. For internal use only.
1SerialNumberchar[20]
2ModelNumberchar[20]
3SoftwareVerchar[10]
4TimeSinceCalHrfloatTime since last calibration in hours.
5OptionsuintMisc. Options.
6AOutOffset_mAint
7AddressRS485char[3] Two character address for RS485 only.
8AInScaleVfloat
9AInOffsetVfloat
10AInScale_mAfloat
11AInOffset_mAfloat
12AoutScaleVfloat
13AoutScale_mAfloat
14SensorZerouint
15Klag[0]float
16Klag[1]float
17Klag[2]float
18Klag[3]float
19Klag[4]float
20Klag[5]float
21Reservedfloat
22Reservedfloat
23Reservedfloat
24Reservedfloat
25Reservedfloat
26Reservedfloat
27Kgain[0]float
28Kgain[1]float
NAME
DATA
TYPE
NOTES
37
Page 41
INDEXNAME
29Kgain[2]float
30Kgain[3]float
31Kgain[4]float
32Kgain[5]float
33Reservedfloat
34Reservedfloat
35Reservedfloat
36Reservedfloat
37Reservedfloat
38Reservedfloat
39ValveTbl[0][open]floatIndex 0: Valve actuation. Must be 0.0.- Do Not Alter
40ValveTbl[0][valve value]uintIndex 0: Valve: D/A value - Do Not Alter
41ValveTbl[1][flow]floatIndex 1: Actual valve opening in % FS. Do Not Alter
42ValveTbl[1][valve value]uintIndex 1: Valve D/A counts corresponding to flow. Do Not Alter
43ValveTbl[2][flow]floatDo Not Alter
44ValveTbl[2][valve value]uintDo Not Alter
45ValveTbl[3][flow]floatDo Not Alter
46ValveTbl[3][valve value]uintDo Not Alter
47ValveTbl[4][flow]floatDo Not Alter
48ValveTbl[4][valve value]uintDo Not Alter
49ValveTbl[5][flow]floatDo Not Alter
50ValveTbl[5][valve value]uintDo Not Alter
51ValveTbl[6][flow]floatDo Not Alter
52ValveTbl[6][valve value]uintDo Not Alter
53ValveTbl[7][flow]floatDo Not Alter
54ValveTbl[7][valve value]uintDo Not Alter
55ValveTbl[8][flow]floatDo Not Alter
56ValveTbl[8][valve value]uintDo Not Alter
57ValveTbl[9][flow]floatIndex 9: Valve fully open. Must be 1.0- Do Not Alter
58ValveTbl[9][valve value]uintIndex 9: D/A count for a fully open valve. Must be 4095.- Do Not Alter
59AutoTune Time ConstantuintDo Not Alter
DATA
TYPE
NOTES
38
Page 42
CALIBRATION TABLE: GAS INDEPENDENT VARIABLES
INDEXNAME
100GasIdentiferchar[27]
101FullScaleRangefloat
102StdTempfloat
103StdPressurefloat
104StdDensityfloat
105CalibrationGaschar[27]
106CalibratedBychar[20]
107CalibratedAtchar[20]
108DateCalibratedchar[10]
109DateCalibrationDuechar[10]
110PID_Kpfloat
111PID_Kifloat
112PID_Kdfloat
113 SensorTbl[0][Sensor Value]uintIndex 0: Must be 120 (zero value)
114SensorTbl[0][Flow]floatIndex 0: Must be 0.0 (zero PFS)
115 SensorTbl[1][Sensor Value]uintA/D value from sensor.
DATA
TYPE
NOTES
116SensorTbl[1][Flow]floatActual Flow in PFS.
117 SensorTbl[2][Sensor Value]uint
118SensorTbl[2][Flow]float
119 SensorTbl[3][Sensor Value]uint
120SensorTbl[3][Flow]float
121 SensorTbl[4][Sensor Value]uint
122SensorTbl[4][Flow]float
123 SensorTbl[5][Sensor Value]uint
124SensorTbl[5][Flow]float
125 SensorTbl[6][Sensor Value]uint
126SensorTbl[6][Flow]float
127 SensorTbl[7][Sensor Value]unit
128SensorTbl[7][Flow]float
39
Page 43
INDEXNAME
129 SensorTbl[8][Sensor Value]uint
130SensorTbl[8][Flow]float
131 SensorTbl[9][Sensor Value]uint
132SensorTbl[9][Flow]float
133 SensorTbl[10][Sensor Value]uint
134SensorTbl[10][Flow]floatFlow in PFS. Should be 1.0
135
136
137
DATA
TYPE
Note:Values will be available for selected gas only.
NOTES
40
Page 44
APPENDIX 6
WARRANTY
Dwyer Mass Flow Systems are warranted against parts and workmanship for
a period of one year from the date of purchase. Calibrations are warranted
for up to six months after date of purchase, provided calibration seals have
not been tampered with. It is assumed that equipment selected by the customer is constructed of materials compatible with gases used. Proper selection is the responsibility of the customer. It is understood that gases under
pressure present inherent hazards to the user and to equipment, and it is
deemed the responsibility of the customer that only operators with basic
knowledge of the equipment and its limitations are permitted to control and
operate the equipment covered by this warranty. Anything to the contrary will
automatically void the liability of Dwyer and the provisions of this warranty.
Defective products will be repaired or replaced solely at the discretion of
Dwyer at no charge. Shipping charges are borne by the customer. This warranty is void if the equipment is damaged by accident or misuse, or has been
repaired or modified by anyone other than Dwyer or factory authorized service facility. This warranty defines the obligation of Dwyer and no other warranties expressed or implied are recognized.
NOTE: Follow Return Procedures In Section 1.3.
TRADEMARKS
Dwyer7 is a registered trademark of Dwyer Instruments.
Buna7 is a registered trademark of DuPont Dow Elastometers.
Kalrez7 is a registered trademark of DuPont Dow Elastomers.
Neoprene7 is a registered trademark of DuPont.
Viton7 is a registered trademark of Dupont Dow Elastometers L.L.C.
41
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