Dwyer GFM4 User Manual

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FUNCTION

+15 Vdc (Optional +12 or +24 Vdc) Power Supply

0 to 5 Vdc or 4 to 20 mA Flow Signal Output

0 to 5 Vdc or 4 to 20 mA Temperature Signal

Output (Optional)

0 to 5 Vdc or 4 to 20 mA Pressure Signal
Output (Optional)

(reserved)

Relay No. 1 - Common Contact

Relay No. 1 - Normally Open Contact

Relay No. 2 - Normally Closed Contact

RS485 (-) (Optional RS232 TX)

(No Connection)

Common

-15 VDC Power Supply (Only for ±15Vdc option)

Common, Signal Ground For Pin 2
(4 to 20 mA return)

Common, Signal Ground For Pin 3
(4 to 20 mA return)

Common, Signal Ground For Pin 4
(4 to 20 mA return)

Common, Power Supply (- DC power for
12 and 24 Vdc)

Common

RS232 Signal GND (RS-485 GND Optional)

Relay No. 1 - Normally Closed Contact

Relay No. 2 - Common Contact

Relay No. 2 - Normally Open Contact

RS485 (+) (Optional RS232 RX)

Chassis Ground

The (+) and (-) power inputs are each protected by a 400 mA 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. DC Power cable length may not exceed 9.5´ (3
meters).

Use of the GFM3/4 flow transducer in a manner other than that specified in this
manual or in writing from Dwyer

Instruments, Inc, may impair the protection

provided by 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 geometry 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, the GFM3/4
model Mass Flow Meter incorporates a Digital Signal Processor (DSP) and non-
volatile memory that stores all hardware specific variables and up to 10 different
calibration tables. Multi parameter flow meters provide accurate data on three
different fluid parameters:
• flow
• pressure
• temperature

The flow rate can be displayed in volumetric flow or mass flow engineering units for
standard or actual (temperature, pressure) conditions. Flow meters can be
programmed locally via the four button keypad and LCD, or remotely, via the RS-
232/RS-485 interface. GFM3/4 flow meters support various functions including:
flow totalizer, flow, temperature, pressure alarms, automatic zero adjustment, 2
SPDT relays output, 0 to 5 Vdc / 0 to 10 Vdc / 4 to 20 mA analog outputs for flow,
pressure and temperature.

4. SPECIFICATIONS
GFM3
Service: Clean gases compatible with wetted parts.
Wetted Materials: 316 SS, 416 SS; Fluoroelastomer, Buna-N, EPR or PTFE O-
rings.
Accuracy: ±1% FS.
Repeatability: ±0.25% FS.
Response Time: 0.6 to 1.0 s to within ±2% of setpoint over 20 to 100% FS.
Output Signal: Linear 0 to 5 VDC (3000 Ω min. load impedance); 0 to 10 VDC
(6000 Ω min. load impedance); 4 to 20 mA (500 Ω max. loop resistance).
Max. Particulate Size: 5 microns.
Temperature Limits: Ambient: 32 to 122°F (0 to 50°C); Dry Gases: 14 to 122°F (-
10 to 50°C).
Power Supply: ±12 VDC; ±15 VDC; ±24 VDC.
Process Connections: 1/8˝ compression fitting for flow rates ≤ 10 L/min; 1/4˝ for ≤
50 L/min; 3/8˝ for ≤ 100 L/min.
Pressure Limits: 500 psi (35 bar).
Leak Integrity: 1 x 10

-9

smL/sec of helium.

Display: 128 x 64 graphic LCD with backlight.

GFM4
Service: Clean gases compatible with wetted parts.
Wetted Materials: 316 SS, 416 SS; Fluoroelastomer, Buna-N, EPR or PTFE O-
rings.
Accuracy: ±1% FS.
Repeatability: ±0.25% FS.
Response Time: 0.6 to 1.0 s to within ±2% of setpoint over 20 to 100% FS.
Output Signal: Linear 0 to 5 VDC (3000 Ω min. load impedance); 0 to 10 VDC
(6000 Ω min. load impedance); 4 to 20 mA (500 Ω max. loop resistance).
Max. Particulate Size: 5 microns.
Temperature Limits: Ambient: 32 to 122°F (0 to 50°C); Dry Gases: 14 to 122°F (-
10 to 50°C).
Power Supply: ±12 VDC; ±15 VDC; ±24 VDC.
Process Connections: 1/8˝ compression fitting for flow rates ≤ 10 L/min; 1/4˝ for ≤
50 L/min; 3/8˝ for ≤ 100 L/min.
Pressure Limits: 200 psia (13.79 barA).
Leak Integrity: 1 x 10

-9

smL/sec of helium.

Display: 128 x 64 graphic LCD with backlight.

In general, "D" Connector numbering patterns are

standardized. There are, however, some connectors with

nonconforming 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 then particular numbers
displayed on the mating connector.

NOTICE

Make sure power is OFF when connecting or disconnecting
any cables in the system.

NOTICE

Figure b-1, GFM3/4 Pin "D"

Connector Configuration

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This manual is related to the following products:

GFM3