M Series Variable Area Flowmeters
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Specifications:
- Product: Variable Area Flowmeters
- Models: G Series (Glass-tube) and M Series (Metal-tube)
- Installation: Vertical mounting for accurate flow reading
Product Usage Instructions:
Installation:
For optimal performance, prior to installation:
- Flush out the pipe or tube leading to the flowmeter.
- Dry the pipe or tube for gas flow applications.
The flowmeter must be installed vertically for accurate flow
reading, except for the Swagelok MH horizontal model.
Reading the Flowmeter:
Glass-Tube Models: Read by the position of the
float or ball within the tube. The flow rate is read at the upper
edge of the float or ball.
Metal-Tube Models: Read with the pointer on the
scale or LED display.
Startup:
- Ensure system media, pressure, and temperature are consistent
with the calibration of the flowmeter for accurate
measurement.
FAQ:
Q: How should the flowmeter be positioned for accurate
readings?
A: The flowmeter should be installed
vertically, except for specific models like the Swagelok MH
horizontal model, to ensure accurate flow readings.
Q: How are Glass-Tube and Metal-Tube models read?
A: Glass-Tube models are read by the position
of the float or ball within the tube, while Metal-Tube models are
read with a pointer on the scale or LED display.
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Variable Area Flowmeters
Installation Instructions G Series and M Series
Safety Definitions
Potential danger to life or of serious injuries.
· Potential for personal injury from electrical shock.
Glass-tube models, G series
Safety Information
Swagelok variable area flowmeters must be installed, operated, and serviced according to NEC, applicable local regulations, and these instructions. Otherwise, serious personal injuries, damage, or both can occur.
The electrical connections provided on any electronic relays should be used as originally supplied and not bypassed or modifed (other than wire length). Only qualified personnel should work on these products.
Metal-tube models, M series
Contents
Safety Definitions . . . . . . . . . . . . . . . . . . . . . 1 Safety Information . . . . . . . . . . . . . . . . . . . . 1 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Reading the Flowmeter . . . . . . . . . . . . . . . . . 2 Reading the Flowmeter Using a
Conversion Factor . . . . . . . . . . . . . . . . . . . . 2 Limit Switches
Without a Junction Box . . . . . . . . . . 3 With a Junction Box . . . . . . . . . . . . 3 Adjusting . . . . . . . . . . . . . . . . . . . . . 4 To an Isolated Switch Amplifier With
Relay Output . . . . . . . . . . . . . . . . . . 5 Output Signal . . . . . . . . . . . . . . . . . . . . . . . 6
Safe Product Use
Follow any enclosed instructions and refer to the product catalog for detailed product information. When using a variable area flowmeter, the total system design must be considered to ensure safe, troublefree performance. Function, material compatibility, adequate ratings, proper installation, operation, and maintenance are the responsibilities of the system designer and user. Improper selection or misuse of the product may result in serious personal injury or property damage.
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Installation
For optimal performance, prior to installation: flush out the pipe or tube leading to the flowmeter. For gas flow applications, dry the pipe or tube
leading to the flowmeter.
The variable area flowmeter must be installed as vertically as possible to ensure the most accurate flow reading, with the exception of the Swagelok MH horizontal model.
Reading the Flowmeter
Glass-Tube Models Glass-Tube flowmeters are read by the position of the float or ball within the flowmeter tube. The flow rate is read at the upper, top edge of the float or ball.
Metal-Tube Models The flow rate is read with the pointer on the scale or the LED display.
G Series Vertical Mount
Direction of flow is from bottom to top in vertical models and can be either right to left or left to right in horizontal models, as specified when ordering.
Left-to-right Horizontal Mount
Align the pipe or tube leading to and from the flowmeter axially with the connections on the flowmeter to keep them free of stress. If necessary, support the pipe or tube leading to and from the flowmeter to prevent vibration being transmitted to the flowmeter.
Startup
1. For accurate flow measurement, the system media, pressure, and temperature should be consistent with the calibration of the flowmeter.
2. Close the integral metering valve on the flowmeter before the system is pressurized. Note: M4 and M4H models do not contain an integral metering valve.
3. Open the shutoff valves upstream and downstream of the flowmeter.
4. Add system pressure slowly.
NOTICE Open the metering valve slowly when starting the flow to prevent damage to the float.
5. Adjust the metering valve until the flowmeter shows the desired flow rate.
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Reading the Flowmeter using a
Conversion Factor
Flowmeters calibrated for one fluid at a specific pressure and temperature can be used to measure other fluids and different pressures and temperatures by using a conversion factor. Use the following equation to calculate the conversion factor. Multiply the conversion factor by the flowmeter reading for flowmeters in gas service to determine the flow rate for the new conditions.
F =
cal new
×
Pnew Pcal
×
273 + Tcal 273 + Tnew
where
F = conversion factor
cal = fluid density of calibrated scale new = new fluid density Pcal = pressure (in standard condition) of calibrated scale Pnew = new pressure (in standard condition) Tcal = temperature of calibrated scale, in °C Tnew = new temperature, in °C
Note: For temperatures in °F, replace 273 in equation with 460.
Example Calibrated scale: = 1.5 kg/m3 P = 7 bar (abs) T = 30°C
F =
1.5 1.5
×
New fluid or conditions:
= 1.5 kg/m3 P = 10 bar (abs) T = 60°C
10
7×
273 + 30 273 + 60
= 1.14
Multiply 1.14 by the calibrated scale to determine the flow rate.
Example:
The flowmeter reading is 100 NL/h or 3.8 SCFH.
100 NL/h × 1.14 = 114 NL/h
3.8 SCFH × 1.14 = 4.3 SCFH
Use the following equation to calculate the conversion factor for flowmeters in liquid service. Multiply the conversion factor by the flowmeter reading to determine the flow rate for the new conditions.
F = square root (cal / new) A conversion factor in case of viscosity change cannot be given in a simplified formula like for the density change. The conversion factor for viscosity change is based on arrays of characteristic measurement curves. Please contact the supplier.
Limit Switches
· Do not wire limit switches for initial installation
while system is in operation.
Up to two limit switches compliant with IEC 60947-5-6 (NAMUR EN 60947-5-6) may be connected to the flowmeter. Connect the limit switch(es) to the desired monitoring device. Note: When using two limit switches, space the limit
switches a mininum of 0.63 in. (16 mm) apart. Note: Any flowmeter with a limit switch installed must
be kept a minimum of 0.24 in. (6 mm) from any moving object containing nickel, iron or cobalt.
Wiring a Limit Switch Without a Junction Box All Models 1. Connect the brown wire extending from the
flowmeter/limit switch assembly to the positive (+) input of the monitoring device. 2. Connect the blue wire extending from the flowmeter/ limit switch assembly to the negative () input of the monitoring device.
Wiring a Limit Switch With a Junction Box
Glass-Tube Models 1. Loosen screws and remove the front cover of the
junction box. 2. Feed the connecting cable (max 16 AWG or 1.31
mm2) through the cable gland and screw down the cable gland. 3. Connect the positive and negative wires. Note: When using one limit switch only, wire to
Terminal 1. When using two limits switches, wire the lower switch to Terminal 1 and the upper switch to Terminal 2.
Terminal 1
Terminal 2
Cable gland
Metal-Tube Models M1 Model 1. Loosen the screw on the connector plug and
remove the plug from the junction box.
Screw Terminal block
Connector plug Cable gland
2. Remove the screw from the plug. 3. Place a screwdriver in the opening, lift and remove
the terminal block.
Screwdriver opening
4. Feed the connecting cable (max 16 AWG or 1.31 mm2) through the cable gland of the plug and screw down the cable gland.
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5. Connect the wires to the positive and negative locations on underside of the terminal block for the minimum, maximum, or both.
6. Reinstall the terminal block into the plug, snapping in place.
7. Reinstall plug onto junction box and replace the screw. Tighten screw.
M2 Model 1. Remove the screws and cover from the flowmeter. 2. Feed the connecting wires through the cable gland
(max 16 AWG) and screw down the cable gland. 3. Connect the wires to the positive and negative
locations of the minimum, maximum, or both. 4. Replace the cover and tighten the screws.
M2 Model
Minimum
Adjusting a Limit Switch Limit switches can be adjusted after installation or set during operation. Glass-Tube Models 1. Remove the cover from the flowmeter. 2. Loosen the two clamping screws fastening the
Mounting rail
Clamping screws
Limit switch
limit switch to the mounting rail of the flowmeter.
3. Slide the limit switch along the mounting rail to set the top for a minimum switch, the bottom for a maximum switch, or both if two switches are installed.
Note: When setting the limit switch, lay the wires so they won’t get damaged during use.
Clamping screw
Cable gland locations
Maximum
M4 and M4H Models 1. Open the housing by turning the cover
counterclockwise with the help of the enclosed plastic wrench. 2. Feed the connecting wires through the cable gland (max 16 AWG) and screw down the cable gland. 3. Connect the wires to the positive and negative locations of the minimum, maximum, or both. 4. Close the housing by turning the cover clockwise with the help of the enclosed plastic wrench.
4. Tighten the clamping screws. 5. Replace the cover.
Minimum
Min
Max
Maximum 4
Metal-Tube Models M1 and M2 Models 1. Remove the screws and cover from the flowmeter. 2. Slide the minimum contact, maximum contact,
or both along the slip coupling to set the corresponding pointers to the desired limit on the scale. 3. Replace the cover and tighten the screws.
M1 Model
Maximum pointer
Minimum pointer
M2 Model
Minimum contact Slip coupling
Maximum contact
Maximum pointer
Minimum pointer
Minimum contact
Slip coupling
Maximum contact
M4 and M4H Models 1. Open the housing by turning the cover
counterclockwise with the help of the enclosed plastic wrench. 2. Slide the minimum contact, maximum contact, or both along the slip coupling to set the corresponding pointers to the desired limit on the scale. 3. Close the housing by turning the cover clockwise with the help of the enclosed plastic wrench. M4 and M4H Models
Minimum
Slip coupling
Maximum
Min
Max
Wiring Limit Switch to a Switch Amplifier With Isolated Relay Output
· Do not wire limit switches for initial installation
while system is in operation.
Note: The limit switch wires are brown (+) and blue (). Note: Additional diagram information is provided for
the switch amplifier by the manufacturer.
Flowmeter
Input 1 1
+2
3
Input 2 4
+5 6
Switch Amplifier
}8
Relay
7
Output 1
9
}11
10
Relay Output 2
12
}14 Supply
15 240 V (ac)
Connection to Customer Switch Amplifier Connection to Swagelok-Offered Switch Amplifier One Limit Switch 1. Connect the limit switch to slot 1 (+) and slot 3 () of
the transistor relay. 2. Connect the outputs of the limit switch to slot 7
and slot 8 for a signal when flow is above the limit switch setting (normally open) or to slot 7 and slot 9 for a signal when flow is below the setting (normally closed). 3. Connect alternating current power to slot 14 (+) and
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slot 15 (-). Connection to Swagelok-Offered Switch Amplifier Two Limit Switches 1. Connect the minimum limit switch to slot 1 (+) and
slot 3 () of the transistor relay. 2. Connect the maximum limit switch to slot 4 (+) and
slot 6 (). 3. Connect the outputs of the minimum limit switch to
slot 7 and slot 8 for a signal when flow is above the limit switch setting (normally open) or to slot 7 and slot 9 for a signal when flow is below the setting (normally closed). 4. Connect the outputs for the maximum limit switch to slot 10 and slot 11 for a signal when flow is above the limit switch setting (normally open) or to slot 10 and slot 12 for a signal when below the setting
4 to 20 mA Output Signal
· Do not wire output signal for initial installation
while system is in operation.
This 2-wire system connects the power supply, flowmeter, and monitoring device in a series circuit. This creates a “current loop” with the flowmeter functioning as a measurement device. The 4 to 20 mA interface requires an auxillary power of 14.8 to 30 V (dc). Swagelok suggests use of a 24 V (dc) power supply.
Maximum Load Equations
Milliampere Output Signal, 2-Wire
Output Supply
4 to 20 mA V = 14.8 to 30 V (dc)
Max load RL = (V [dc] 14.8) / 0.02 Terminals See drawings
The output will be proportional to the measured flow based on the scale on the flowmeter. Wire the loop according to the appropriate diagram below.
M2 Model
Power supply
(normally closed). 5. Connect alternating current power to slot 14 (+) and
slot 15 ().
RL
4 to 20 mA
M4 and M4H Models
Power supply
= +
11+
– RL
4 to 20 mA
12-
For product technical data, including materials of construction, see the Swagelok Variable Area Flowmeters catalog, MS-02-346.
Swagelok–TM Swagelok Company © 2008-2025 Swagelok Company MS-CRD-0111 RevB, May 2025
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Documents / Resources
 | Swagelok M Series Variable Area Flowmeters [pdf] Installation Guide G Series, M Series, M Series Variable Area Flowmeters, M Series, Variable Area Flowmeters, Area Flowmeters, Flowmeters |