G-1
FLOW SWITCHES
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Set Point Switch
Series
Body
Materials
Water Air
50 cc to 300 cc/min. 2 to 50 SCFH FS-926 Alloys
0.1 to 1.0 GPM (oil) — FS-930
0.1 to 1.5 GPM — FS-4 Engineered Plastics
0.1 to 1.5 GPM 0.5 to 25.0 SCFM FS-925
Alloys0.1 to 1.5 GPM — FS-927
0.15 to 2.0 GPM — FS-380
0.25 to 2.0 GPM — FS-380P Engineered Plastics
0.1 to 60 GPM — RFS-2500 Rotorflow1Eng. Plastics & Alloys
0.5 to 3.0 GPM — FS-480 Alloys
0.5 to 5.0 GPM — FS-150
Engineered Plastics0.5 or 2 GPM — FS-400P
0.25 to 5.0 GPM — FS-500
0.5 to 20.0 GPM 1.0 to 160.0 SCFM FS-10798
Alloys
0.5 to 100 GPM — FS-200
0.75 to 10.0 GPM — FS-400
0.75 to 14.0 GPM — FS-400 Adjustable
1.0 to 15.0 GPM — FS-200 Adjustable
Dependent on Pipe Size
and Paddle Length — FS-550 Series
INTRODUCTION
Flow Switches
Piston
Shuttle
Paddle
Unique Designs . . . For Use in Liquids or Gases
GEMS’ line of flow switches features a broad range of configurations for
use in liquids or gases. At preset rates, ranging from 50 cc/min. to
100 GPM, GEMS switches will initiate alarm actuation or automatic
shut-down of a system.
These switches feature high quality, corrosion-resistant materials for
use in the toughest environments. Material choices, ranging from
stainless steel to Ryton®, offer vast chemical compatibility. Versions
include switches with fixed or adjustable actuation settings, models for
viscosity compensation or high pressures, in-line models and designs
to satisfy any mounting or space requirement.
Variety of Operating Principles
The versatile GEMS Flow Switch line utilizes four basic operating
principles. This catalog is organized into four operational types: Piston,
Shuttle, Paddle and Electronic. The Shuttle models are for use with high
flow rates; the Piston types are designed for low flow rates; the Paddle
for large line sizes and the Electronic switches encompass state-of-the-
art electronics and positive visual indication.
Flow Rate Selection Guide
Contents Page Start
Piston Type ................................................................ G-2
Shuttle Type ............................................................G-16
Paddle Type ............................................................G-23
Note:
1. See Section E.
Piston Types
Shuttle Types
Paddle Types
G -2
FLOW SWITCHES
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O-RING
POLYSULFONE
HOUSING
SPRING
PERMANENT
MAGNET
HERMATICALLY
SEALED SWITCH
PISTON
HOUSING
O-RING
INLET
FITTING
24" (609.6 mm)
WIRE LEADS
NO. 18 AWG
9/16" -18 UNF-2B
BOTH PORTS
O-RING
BY-PASS
HOLES
METERING
ORIFICE
LOW-FLOW
PISTON
MAGNET CARRIER
PISTON
SWITCH-FLOW
MAX
IN
MIN
OUT
MFRS. P/N
SPEC.
MFRS. S/N
TYPE NO.
CONTR. NO.
STOCK NO.
FLOW ACTUATION
ADJUSTMENT
Piston Type Switches – For Low Flow
Rates in Liquids and Gases
Models for liquid flow rates as low as 50 cc/min. and gas flow rates
as low as 2 SCFH
Small, compact housings with port sizes from 1/4˝ NPT
Precision built for superior accuracy
Typical Applications
Protect your expensive electronic equipment from coolant flow failure on...
• Laser Heads • Welders • Power Supplies • High Speed Spindles • X-Ray Tubes
• Semiconductor Equipment
Assure proper lubrication flow to critical bearings or gears to prevent system
downtime on...
• Presses • Rotating Equipment • Conveyors • Machine Tools • Robotics
Ensure system integrity in processing and dispensing equipment on...
• Water Purifications and Filtering • X-Ray film Processing
• Beverage dispensing • Chemical additives • Gas sampling • Distilling
Design Data
General Operating Principles Low-Flow Switches
(FS-4 and FS-925
Series shown)
A piston, encapsulating a permanent magnet, is
positioned in the flow path within the unit housing. When
displaced by the pressure differential from fluid flow, this
piston magnetically actuates a hermetically sealed reed
switch (SPST or SPDT, depending on the series) within
the unit. The piston metering land diameter precisely
sets the actuation point by regulating bypass clearance.
A stainless steel spring provides positive piston return as
flow decreases. The reed switch, when actuated, can be
used to operate remote alarms or indicators. Or, it may be
integrated into automatic system controls.
Partial Cutaway
(FS-926)
An additional, lap-fitting piston is used in GEMS FS-926
Series to accurately detect low-flow rates. Calibration
is determined by one or more metering holes in the top
of the low-flow piston, which regulates bypass flow,
and therefore the actuation setting. When metered
bypass flow is exceeded, the resultant pressure
differential displaces the low-flow piston, moving the
magnet carrier piston to actuate the reed switch. Two
large bypass holes in the piston skirt are exposed after
actuation to maintain low pressure drop.
Externally Adjustable Switches
The
FS-10798
Series offers
infinite flow
settings
from 0.5 to 20 GPM. Versions suitable for gas flow
monitoring are also available.
G-3
FLOW SWITCHES
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VISCOSITY
COMPENSATING PISTON
O-RING
OVER-MOLDED PISTON
WITH MAGNET
METERING DISC
SPRING
O-RING
ENCAPSULATED
REED SWITCH
PISTON
PISTON
INLET
FITTING
SPRING PLUG
SPRING
O-RING
Viscosity Compensating Switches
Partial Cutaway
(FS-930 Series)
When temperatures of viscous fluids change, so do their flow properties. With
viscosity lowered by increasing temperature, a greater flow is generally required to
create actuation pressure differential. A unique patented piston within GEMS FS-930
Series switches accommodates these changes in fluid viscosity while maintaining
accurate switch actuation. Units can detect flow rates with 20% accuracy for liquid
viscosities between 40 to 1000 SSU.
Low Pressure Drop Switches
The key to the excellent flow qualities of the FS-150 and FS-380 Series switches
is the dual diameter internal bore. At flow rates below the actuation point, the fluid
passes around the piston and metering disc within the “metering bore.” As fluid flow
increases past the actuation point, the metering disc enters the “flow bypass bore”
where the increased diameter provides generous flow paths. The result is a low
pressure drop for high flow rates and less susceptibility to fouling.
Typical Piston and Spring Removal
Accumulation of foreign debris should periodically be removed from these switches.
GEMS’ designs provide for easy piston and spring removal for this occasional
cleaning. Recommended cleaning procedures are provided in the Instruction Bulletin
shipped with each unit. 150 micron filtration is recommended for the FS-150 Series;
100 micron for FS-380, 50 micron filtration is recommended for all other piston type
switches.
NOTE: All air/gas Flow Switches are factory calibrated using a special piston. Water calibrated units are not
recommended for air/gas applications.
PISTON TYPE
Contents Page Start
FS-4 Series
Molded Plastic Construction ..................... G-4
FS-150 Series
Straight-Through Flow Path,
Ryton Material ................................................... G-5
FS-380 Series
High Pressure Inline ....................................... G-6
FS-380P Series
Inline – Plastic Flow ........................................ G-7
FS-480 Series
Low Pressure Drop .......................................... G-8
FS-927 Series
Miniature Brass Switches ............................ G-9
FS-925 Series
General Purpose .............................................G-10
FS-926 Series
Low Flow ............................................................G-10
FS-10798 Series
Externally Adjustable ..................................G-12
FS-930 Series
Viscosity Compensating .............................G-14
G-4
FLOW SWITCHES
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Housing
and Piston
Material
Flow
Setting
GPM
Part Numbers
SPST Switch With
SPDT Switch
N.O., No Flow N.C., No Flow
Ryton®
0.1 122340 122346 122352
0.25 122341 122347 122353
0.5 122342 122348 122354
0.75 122343 122349 122355
1.0 122344 122350 122356
1.5 122345 122351 122357
Material Adapter Size Part Numbers
Ryton®1/8˝ NPT* 123028
1/4˝ NPT* 123029
Polypropylene 1/4˝ NPT* 158602
1/2˝ Barb** 158603
.586
15
1.00
25
3.640
92
3.80
97
1.255
32
LEADWIRES
9/16˝ -18 UNF-2B THREAD
WITH O RING SEAL PORT
.920 DIA
23
1.90
48
2.0
1.5
1.0
0.5
00 0.5 1.0 1.5 2.0
3.0
2.5
FLOW RATE - GPM
PRESSURE DROP (PSID)
Part No. 122355
Part No. 122357
Part No. 122352
Tests conducted with units in vertical position (lead wires up) with water
at +70 F (21 C).
1" (25.4 mm)
DIA.
.87 FLAT
5/8"
(15.9 mm)
1/2"
(12.7 mm)
1/4" NPT
3/4" (19.0 mm) DIA.
.62 FLAT
1/2" (12.7 mm)
3/8" (9.5 mm)
.54" (13.7 mm)
DIA.
1/2" (12.7 mm)
DIA.
3/4" (19.0 mm)
HEX 1"
(25.4 mm)
.25"
(6.3 mm)
1/2" Barb
1/8" NPT
FS-4 Series –
Low Cost, Molded Plastic Construction
Flow Rate Settings: 0.1 GPM to 1.5 GPM
Port Size: 9/16˝-18 UNF
Primary Construction Material: Ryton®
Setting Type: Fixed
The FS-4 Series makes flow protection economical for a broad range of industrial
applications such as welders, lubrication systems, medical sterilizers and laundry
chemicals dispensing.
Specifications
Wetted Materials
Housing and Piston Ryton® R4
Spring 316 Stainless Steel
O-Ring Viton®
Other Wetted Parts Epoxy
Operating Pressure, Maximum 250 PSIG (17.2 bar) @ 70°F (21°C)
Operating Temperature 0°F to 225°F (-17°C to +107°C)
Set Point Accuracy ±15% Maximum
Set Point Differential 20% Maximum
Switch* SPST or SPDT, 20 VA (SPDT: 240 VAC Max.)
Inlet/Outlet Ports 9/16˝ -18 UNF-2B Thread
Recommended Filtration 50 Microns or Better
Electrical Termination
SPST 18 AWG, Zipcord, 24˝ Long
SPDT 18 AWG, PVC 24˝ Long Leads
* See “Electrical Data” on Page X-5 for more information.
How To Order – Standard Models
Note:
Flow settings are calibrated using water @ +70°F on increasing flow, with units in a vertical position
(lead wires up).
Port Adapters for FS-4
Converts 9/16˝ threaded ports to NPT or barbed connection. Made of Ryton®-R4 or
polypropylene with O-Rings in place.
CAUTION: Do not exceed 15 in./lbs. maximum torque when installing adapter fittings.
*Wrench flats provide for proper
assembly.
**Accepts 1/2˝ I.D. flexible hose
– Stock Items.
U.L. Recognized —
File No. E31926
CSA Listed —
File No. LR30200
Dimensions
inch
mm
Pressure Drop – Typical
G-5
FLOW SWITCHES
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Flow Settings
GPM
Part Numbers
Normally Open @ No Flow Normally Closed @ No Flow
0.5 129660 129666
1.0 129661 129667
2.0 129662 129668
3.0 129663 129669
4.0 129664 129670
5.0 129665 129671
0
0
1
1
2
2
3
3 4 5 6 7
4
5
PRESSURE DROP (PSID)
FLOW RATE - GPM
Part No.
129663
Part No. 129660
Part No. 129661
Part No. 129662
Part No.
129665
Part No.
129664
Tests conducted with units in a horizontal position with water at +70°F (21°C).
Data will vary slightly for vertically mounted units.
PISTON TYPE
FS-150 Series – Straight Flow Path with
Low Pressure Drop
Flow Rate Settings: Liquids: 0.5 GPM to 5 GPM
Port Size: 1/2˝ NPT
Primary Construction Material: Polypropylene
Setting Type: Fixed
These slim, inline switches reduce pressure drop to a minimum. They incorporate
a unique, dual-diameter, internal bore and piston configuration to minimize flow
constriction. Liquids are able to smoothly pass around the piston and flow through
the switch with little pressure loss to the down stream line.
Specifications
Wetted Materials
Housing Polypropylene, Hydrolytically Stable, Glass Reinforced
Piston Ryton® -R4, 316 Stainless Steel
O-Ring Viton®
Spring 316 Stainless Steel
Operating Pressure, Maximum 200 PSIG (13.8 bar)
@+70°F to +150°F (+21.1°C to 65.5°C)
150 PSIG (10.3 bar)
@+150°F to +212°F (+65.5°C to +100°C)
Operating Temperature 0°F to 212°F (-17.8°C to +100°C)
Set Point Accuracy ±15%
Set Point Differential 20% Maximum
Switch* SPST, 20 VA
Inlet/Outlet Ports 1/2˝ NPT Male
Electrical Termination 1/4˝ Male Quick Connect Terminals (2)
*See “Electrical Data” on Page X-5 for more information.
How To Order – Standard Models
Specify Part Number based on flow setting and switch operation.
Notes:
1. Flow settings are calibrated using water @ +70°F on increasing flow, with units in a horizontal position
(terminals up).
2. Care should be taken by specifiers to ensure fluid compatibility with the above listed wetted materials.
3. Use of 150 micron filtration is recommended.
– Stock Items.
U.L. RECOGNIZED —
FILE NO. E31926
CSA Listed —
File No. LR30200
Patent #
4.996.396
Dimensions
Note: Cable output available. Please consult factory.
Pressure Drop - Typical
G-6
FLOW SWITCHES
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Flow Settings
GPM1
3/8˝ NPT Male 3/8˝ Tube Compression Fitting 1/2˝ NPT Male
Brass Stainless Steel Stainless Steel Brass
0.15 181130 193482 212136 —
0.25 168432 179992 177592 192562
0.50 168433 179993 177593 192563
1.00 168434 179994 177594 192564
1.50 168435 179995 177595 192566
2.00 178353 179996 225525 192567
Gems FS-380
4.0˝
(102 mm)
1.25˝
(32 mm)
FLOW
7/8˝ -HEX
Gems FS-380
3.45˝
(88 mm)
0.85˝
(22 mm)
1.00˝
(25 mm)
3/4˝ -HEX
FLOW
11/16˝ -HEX
4.02˝
(102 mm)
0.86˝
(22 mm)
1.13˝
(29 mm)
FLOW
14
12
10
8
6
4
2
0
01234567
FLOW RATE - GPM
PSI DROP
SPRING 170342
1.5 + 2.0 GPM
SETTINGS
SPRING 10397
0.25 - 1.00 GPM
SETTINGS
FS-380 Series – Compact Flow Switch
for High Inline Pressures
Flow Rate Settings: 0.15 GPM to 2.00 GPM
Port Size: 3/8˝ NPT Male
Primary Construction Material: Brass or Stainless Steel
Setting Type: Fixed
These rugged inline flow switches use 100 micron filtration and are less susceptible
to clogging than other high-pressure inline flow switches. The one-piece magnetic
PPS composite piston makes the FS-380 ideal for high-pressure applications such
as industrial cleaning equipment. The FS-380 is also an excellent choice for semicon
cooling applications where simple design and reliable operation are required.
Specifications
Wetted Materials
Housing Brass or 316 Stainless Steel
Piston PPS Composite, Epoxy
Spring 316 Stainless Steel
O-Ring Fluorocarbon
Operating Pressure, Maximum 1500 PSI (107 bar)
Operating Temperature -20°F to +275°F (-28.8°C to +135°C)
Set Point Accuracy ±20% Maximum
Set Point Differential 20% Maximum
Switch* SPST, 20VA, N.O. at no Flow
Electrical Termination No. 22 AWG, 24˝ to 26˝ Polymeric leads
*See “Electrical Data” on Page X-5 for more information.
How To Order – Standard Models
Specify Part Number based on flow settings.
Spacing
To prevent sensor to sensor magnetic field interference, follow the spacing
guidelines below.
U.L. Recognized
File No. E31926
Dimensions
1/2˝ NPT Ports
3/8˝ NPT Ports
3/8˝ Tube End Compression Fitting
Pressure Drop – Typical
– Stock Items.
Note:
1. Flow settings are calibrated using water @ 70°F on increasing flow with units in horizontal position.
Consult factory for other fluid compatibility.
2 13/64˝
1 1/4˝2 3/8˝
1 1/2˝
FLOW
Gems FS-380
FLOW
Gems FS-380
FLOW
Gems FS-380
FLOW
Gems FS-380
NOTE SWITCH
ORIENTATION
G-7
FLOW SWITCHES
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Flow Settings
GPM
Part Numbers
3/8˝ NPT Male 1/4˝ QDC Male*
0.07 216445** 216446**
0.15 209876 203206
0.25 197081 197091
0.50 197082 197092
1.00 197083 197093
1.50 197084 197094
2.00 197085 197095
Description Part Numbers
Straight Through with Shut-Off Valve
1/4˝ NPT Male Pipe Thread 195787 198063
1/4˝ BSPT Male Pipe Thread 198064 195788
3/8˝ NPT Male Pipe Thread 198065 198066
3/8˝ BSPT Male Pipe Thread 198067 198068
1/4˝ O.D., .27˝ I.D. (6 mm O.D., 4.3 mm I.D.) Polytube 198096 198097
3/8˝ O.D., 1/4˝ I.D. (9.5 mm O.D., 6 mm I.D.) Polytube 198099 198098
1/4˝ (6.4 mm) I.D. Barb 198401 198402
5/16˝ (7.9 mm) I.D. Barb 198403 198404
3/8˝ (9.5 mm) I.D. Barb 198408 198405
1/4˝ O.D. (6.4 mm) O.D. JG®198470 198406
3/8˝ O.D. (9.5 mm) O.D. JG®198459 198407
FLOW
FLOW
11/16˝ HEX
11/16˝ HEX
4.00˝
(102 mm)
4.22˝
(107 mm)
1.00˝
(25 mm)
1.00˝
(25 mm)
0.75˝
(19 mm)
ACROSS FLATS
0.75˝
(19 mm)
ACROSS FLATS
0.43˝
(11 mm)
DIA. TYPICAL
FLOW
FLOW
11/16˝ HEX
11/16˝ HEX
4.00˝
(102 mm)
4.22˝
(107 mm)
1.00˝
(25 mm)
1.00˝
(25 mm)
0.75˝
(19 mm)
ACROSS FLATS
0.75˝
(19 mm)
ACROSS FLATS
0.43˝
(11 mm)
DIA. TYPICAL
PISTON TYPE
FS-380P Series – Industrial Strength
Inline Plastic Flow Switch
Flow Rate Settings: 0.25 GPM to 2.00 GPM
Port Size: 3/8˝ NPT Male and 1/4˝ Quick Disconnect (QDC) Male
Primary Construction Material: Polypropylene
Setting Type: Fixed
This rugged inline flow switch offers the same superior performance to
non-clogging as its metal cousin (FS-380). The fixed set point and simple design
make it a dependable switch. The FS-380P is an ideal choice for coolant applications
requiring reliable flow detection in HVAC, semiconductor, welding, medical and
other industries. 1/4˝ quick disconnect units have a host of snap-on mating
adapters to fit most piping requirements.
Specifications
Wetted Materials
Housing Glass Reinforced Polypropylene
Piston PPS Composite
Spring 316 Stainless Steel
O-Ring Fluorocarbon
Operating Pressure 125 PSI (8.6 bar) @ 70°F (21°C),
50 PSI (3.4 bar) @ 212°F (100°C)
Operating Temperature 0°F to 212°F (-18°C to +100°C)
Set Point Accuracy 20% of Set Point
Set Point Differential 20% Maximum
Switch* SPST, 10VA, N.O. at no Flow
Electrical Termination 24˝ to 26˝ Polymeric Leads, 22 AWG
Filtration 100 Micron
Approvals CUL
*See “Electrical Data” on Page X-5 for more information.
How To Order
Specify Part Number based on flow settings. Adapters
for the 1/4˝ Quick Disconnect (QDC) Male unit are listed
in the table at right.
* See selection of adapters at right.
QDC = Quick Disconnect
** Set point accuracy 0.06 to 0.1 GPM
– Stock Items.
Dimensions
1/4˝ Quick Disconnect Male Adapter
See table at bottom right for adapter Part Numbers.
3/8˝ NPT Port
Acetal Adapters for 1/4˝ Quick Disconnect
Male Tube Fitting Units (180°F max.)
These adapters are available with or without an integral
shut-off valve. The shut-off valve will stop line flow
when the adapter is removed from the unit. Flow
resumes when connected.
Typical shown: 1/4˝ NPT Male
Pipe Thread with Shut-off Valve
JG® is a registered trademark of John Guest USA, Inc.
File No. E31926
G-8
FLOW SWITCHES
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Flow Settings*
GPM 1/2˝ NPT Port 3/4˝ NPT Port 1/2˝ Tube
Compression Fitting
0.50 206915 204715 204710
1.00 206916 204716 204711
1.50 206917 204717 204712
2.00 206918 204718 204713
3.00 206919 204719 204714
1/2˝ TUBE END
COMPRESSION
FITTING
1.00˝
25.4
7/8˝ HEX
7/8˝ HEX
REF
1.00˝
25.4 REF
1.00˝
25.4 REF
1.00˝
25.4 REF
1.00˝
25.4 REF
1.00˝
25.4 REF
4.94˝
125 REF
4.95˝
125 REF
5.40˝
137 REF
1.50˝
38 REF
1.50˝
38 REF
1.50˝
38 REF
1/2˝ TUBE END
COMPRESSION
FITTING
1.00˝
25.4
7/8˝ HEX
7/8˝ HEX
REF
1.00˝
25.4 REF
1.00˝
25.4 REF
1.00˝
25.4 REF
1.00˝
25.4 REF
1.00˝
25.4 REF
4.94˝
125 REF
4.95˝
125 REF
5.40˝
137 REF
1.50˝
38 REF
1.50˝
38 REF
1.50˝
38 REF
1/2˝ TUBE END
COMPRESSION
FITTING
1.00˝
25.4
7/8˝ HEX
7/8˝ HEX
REF
1.00˝
25.4 REF
1.00˝
25.4 REF
1.00˝
25.4 REF
1.00˝
25.4 REF
1.00˝
25.4 REF
4.94˝
125 REF
4.95˝
125 REF
5.40˝
137 REF
1.50˝
38 REF
1.50˝
38 REF
1.50˝
38 REF
0.00
0.0 1.0 2.0 3.0 4.0 5.0 6.0
FLOW RATE IN GPM
PSID
7.0 8.0 9.0 10.0 11.0 12.0 13.0
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
10.00
11.00
12.00
13.00
14.00
15.00
SWITCH ASSY.
FLOW BODY
PISTON ASSY. SPRING
FS-480 Series – Stainless Steel Flow
Switch for Large Flow, Low Pressure Drop
Flow Rate Settings: 0.50 GPM to 3.00 GPM
Port Size: 1/2˝ NPT, 3/4˝ NPT, 1/2˝ Tube Compression Fitting
Primary Construction Material: 316 Stainless Steel
Setting Type: Fixed
The FS-480 large-body inline flow switch delivers ample flow rates with minimal
pressure drop. 25% larger than its FS-380 sibling, the FS-480 is ideal for processes
that push more fluid through their systems and demand low pressure drops. Designed
to accommodate the Semiconductor Industry’s move to larger 300 mm wafer and
cross-over equipment, this switch is also perfect for critical medical equipment
applications. A glass-reinforced PPS piston and forged 316 stainless steel body make
this sensor rugged enough for high pressure lubrication and cooling systems as
well. This simple, yet meticulously perfected design provides the reliability required
in critical applications while allowing for much lower pressure drop rates than other
available switches.
Specifications
Wetted Materials
Housing/End Fitting 316 Stainless Steel
Piston PPS, Epoxy
Spring 316 Stainless Steel
O-Ring Fluorocarbon
Operating Pressure, Maximum 1000 PSI (69 bar)
Operating Temperature -20°F to +250°F (-28.8°C to +121°C)
Set Point Accuracy ±20% Maximum
Set Point Differential 20% Maximum
Recommended Filtration 100 Micron or better
Switch* SPST, 20VA, 120/240 VAC, N.O. at no Flow
Electrical Termination No. 22 AWG, 24˝ PVC Cable
*See “Electrical Data” on Page X-5 for more information.
Pressure Drop – Typical 1.0 GPM Set Point
Dimensions
1/2˝ NPT Ports
3/4˝ NPT Ports
1/2˝ Tube End Compression Fitting
*Calibrated with unit in horizontal position.
How To Order – Standard Models
Specify Part Number based on flow settings.
Straight design and large bore body minimizes pressure drop.
File No. E31926
G-9
FLOW SWITCHES
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Flow Settings
GPM
Part Numbers
Brass Stainless Steel
Normally Open @ No Flow Normally Closed @ No Flow Normally Open
0.10 70820 70826 26969
0.25 70821 70827 26970
0.50 70822 70828 26971
0.75 70823 70829 26972
1.00 70824 70830 26973
1.50 70825 70831 26974
2-3/4"
(69.9 mm)
1/4" NPT
1"
(25.4 mm)
OUT
1"
(25.4 mm)
1"
(25.4 mm)
IN
5/8"
(15.9 mm)
3/8"
(9.5 mm)
1/4" NPT
G-12a ill
4
2
1
3
0
0 0.5 1.0 1.5 2
FLOW RATE - GPM
PRESSURE DROP (PSID)
Part No. 70823
Part No. 70820
Tests conducted with units in vertical position (lead wires up) with water at
+70°F (21°C).
PISTON TYPE
FS-927 Series – Small Design
for Tight Instrumentation Packages
Flow Rate Settings: 0.10 GPM to 1.50 GPM
Port Size: 1/4˝ NPT
Primary Construction Material: Brass, Stainless Steel
Setting Type: Fixed
Measuring only 1˝ x 2-3/4˝, these compact switches are ideal for use where space
is at a premium. Designed for use with water and oil, these switches are suitable for
high volume OEM applications. They are ideal for coolant or lubricant flow monitoring
in portable equipment and many other applications with space constraints.
Specifications
Wetted Materials
Housing and Piston Brass, Stainless Steel
Spring 316 Stainless Steel
Other Wetted Parts Stainless Steel
Operating Pressure, Maximum 1000 PSIG (69 bar)
Operating Temperature -20°F to +200°F (-29°C to +93.3°C)
Set Point Accuracy ±15%
Set Point Differential 20% Maximum
Switch* SPST, 20 VA
Inlet/Outlet Ports 1/4˝ NPT
Electrical Termination No. 18 AWG, 24
˝
L., PVC Lead Wires
*See “Electrical Data” on Page X-5 for more information.
How To Order – Standard Models
Specify Part Number based on flow setting and switch operation.
Liquids other than water: Special calibration is available from Gems for media other
than water. Please consult factory with your requirements, including flow media,
operating pressure, flow set point and liquid viscosity (SSU).
Notes:
1. Flow settings are calibrated using water @ +70°F on increasing flow, with units in a vertical position
(lead wires up).
2. Care should be taken by specifiers to ensure fluid compatibility with the above listed wetted materials.
3. Use of 50 micron filtration is recommended.
– Stock Items.
U.L. Recognized —
File No. E31926
CSA Listed —
File No. LR30200
Dimensions
Pressure Drop – Typical
G-10
FLOW SWITCHES
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O-RING
BY-PASS
HOLES
METERING
ORIFICE
LOW-FLOW
PISTON
MAGNET CARRIER
PISTON
UL Approved
Explosion-Proof
1/4" (6.3 mm)
2-3/8"
(60.3 mm)
1-1/4" (31.7 mm)
3/4"
(19.0 mm)
1/4" NPT
BOTH PORTS
1-3/4"
(44.4 mm)
4-1/8"
(104.7 mm)
1"
(25.4 mm)
27/32" (21.4 mm)
9/32" DIA. (7.1 mm)
MTG. HOLES (2)
1/2" (12.7 mm)
G-11b ill
1/2"
(12.7 mm)
FS-925 Series – General Purpose
Flow Rate Settings: Liquids: 0.1 GPM to 1.5 GPM
Air/Gases: See Flow Settings at right
FS-926 Series – Low Flow
Port Size: 1/4˝ NPT
Primary Construction Material: Brass or Stainless Steel
Setting Type: Fixed
Flow Rate Settings: Liquids: 50-300 cc/min.
Air/Gases: See Flow Settings at right
These two series of precision-calibrated switches provides reliable and consistent
performance; repeatability is within 1%. FS-925 and FS-926 units are factory preset
for actuation at specified flow rates.
These switches provide accurate detection of excessive or insufficient flow rates
in such applications as: protecting against loss of fluid flow in hydraulic systems,
assuring proper coolant flow in semiconductor processing equipment, monitoring high
pressure lubrication systems, and ensuring proper air flow in water/waste systems.
Specifications
Wetted Materials
Housing Brass or 316 Stainless Steel
Piston
In Brass Housing Polysulfone for water; Brass for oil or air
Stainless Steel Housing 316 Stainless Steel
Low Flow Piston (FS-926) Same as Housing
Spring 316 Stainless Steel
O-Ring Viton®
Other Wetted Parts Epoxy
Pressure Rating
Operating, Maximum 1000 PSIG (69 bar)
Proof 2500 PSIG (172 bar)
Burst 5000 PSIG (345 bar)
Operating Temperature
With Brass or S.S. Piston -20°F to +300°F (-29°C to +148.9°C)
With Polysulfone Piston -20°F to +225°F (-29°C to +107.2°C)
Repeatability 1% Maximum Deviation
Set Point Accuracy ±10%
Set Point Differential 15% Maximum
Switch* SPDT, 20 VA
Inlet/Outlet Ports 1/4˝ NPT
Electrical Termination No. 18 AWG, 24˝ L., Polymeric Lead Wires
*See “Electrical Data” on Page X-5 for more information.
Double Piston Detects Minute Flow – FS-926
An additional, lap-fitted
piston is used in Gems
FS-926 Series to accurately
detect low-flow rates.
Calibration is determined
by one or more metering
holes in the end of the low-
flow piston, which regulate
bypass flow, and therefore
the actuation setting.
When metered bypass flow is exceeded, the resultant pressure differential displaces
the low-flow piston, moving the magnet carrier piston to actuate the reed switch.
Two large bypass holes in the piston skirt are exposed after actuation to maintain low
pressure drop.
FS-925/926 Series
U.L. Recognized — File No. E31926
CSA Listed — File No. LR30200
FM Approved — File No. 1H3A2.AX
and 0A8A3AE
Both the FS-925 and FS-926 use a spring-loaded
piston to detect positive flow with great precision. They
act upon direct fluid flow and will not show “false-
positive” flow indication as can happen with sensors
using indirect sensing methods such as pressure
measurement. The FS-926 incorporates an additional
lap-fitted piston for very low flows; see below.
Dimensions
Electrical Connection, 1/2˝ NPT Conduit
G-11
FLOW SWITCHES
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Line
Pressure
Actuation Point
FS-925 FS-926
Min. Max. Min. Max.
5 PSIG (Minimum) 0.5 SCFM 10 SCFM 2 SCFH 15 SCFH
100 PSIG 1.5 SCFM 25 SCFM 7 SCFH 50 SCFH
Flow Settings
GPM, ±10%
Part Numbers
Brass 316 S.S.
0.10 26914 26926
0.25 26915 26927
0.50 26916 26928
0.75 26917 26929
1.00 26918 26930
1.50 26919 26931
Wire Color Terminal
Orange N.O.
Black Common
Red N.C.
Flow Setting Part Numbers
cc/Min. ±10% Equiv. GPM Brass Material 316 S.S. Material
50 .013 26938 26951
100 .025 26939 26952
150 .045 26941 26953
200 .055 26942 26954
250 .065 26943 26955
300 .075 26944 26956
2
1
3
0
0.05 .75 1.0 1.5 2
4
FLOW RATE - GPM
Tests conducted with units in vertical position (lead wires up) with water at
+70°F (21°C).
PRESSURE DROP (PSID)
Part No. 26914
Part No. 26919
Part No. 26917
1.0
0.5
1.5
0
0 10050 200150 300250 400350
2.0
FLOW RATE - cc/Min.
Tests conducted with units in vertical position (lead wires up) with water at
+70°F (21°C).
PRESSURE DROP (PSID)
Part No. 26944
Part No.
26938
Part No. 26941
PISTON TYPE
Flow Settings, Air (Typical)
Dependent on operating line pressure. Examples of set point ranges at a given line
pressure are shown below.
Minimum 5 PSI line pressure required.
Gas Calibration
Water flow units should not be used for air/gas applications: Gas flow units have a
special dash-pot piston for reliable operation. Gas calibration is dependent upon line
pressure, switch orientation, and the specific type of gas. The calibrated flow set point
is subject to change with fluctuations in line pressure.
How To Order – Standard Models – Water Calibration
Specify Part Number based on desired housing material and flow setting.
Liquids other than water: Special calibration is available from GEMS for media other
than water. Please consult factory with your requirements, including housing material
(brass or stainless steel), flow media, operating pressure, flow set point and liquid
viscosity (SSU). A lot charge will be applied for special calibrations.
Gas flow: Consult factory for available calibrations. Specify: Housing material (brass
or stainless steel), gas type, mounting orientation, operating pressure and actuation
setting (SCFM or SCFH) and normal flow rate. A lot charge will be applied for special
calibrations.
FS-925 Series – General Purpose
FS-926 Series – Low Flow Standard Wiring Color Code
Notes:
1. Flow settings are calibrated using water @ +70°F on increasing flow, with units in a vertical position
(lead wires up). Consult factory regarding special flow setting calibration.
2. Temperature changes will slightly affect the standard water or gas flow settings listed. Oil flow settings
will vary with viscosity.
3. Use of 50 micron filtration is recommended.
– Stock Items.
Pressure Drop - Typical
FS-925 Series
FS-926 Series
FS-925 and FS-926 switches are U.L. Approved for
Class I, Division 2, Groups A, B, C, D hazardous
locations.
They are also available with FM-approved, explosion-
proof junction box for Class I, Division 1, Group
D hazardous locations. Units must be assembled
completely at GEMS.
U.L. Approved — File No. E183854
G-12
FLOW SWITCHES
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UL Approved
Explosion-Proof
SWITCH-FLOW
MAX IN
MIN
OUT
MFRS. P/N
SPEC.
MFRS. S/N
TYPE NO.
CONTR. NO.
STOCK NO.
4-1/8"
(104.7 mm)
2"
(50.8 mm)
3/4"
(19.0 mm)
5/8"
(15.8 mm)
1-1/4"
(31.7 mm) 1/2" NPT BOTH PORTS
FLOW ACTUATION ADJUSTMENT
1-1/16"
(26.9 mm)
MAX.
1/2"
(12.7 mm)
IN
FS-10798 Series – Externally Adjustable for
Water, Oils and Gases
Flow Rate Settings: Liquids: Infinite Adjustment between 0.5 GPM and
20.0 GPM
Air/Gases: See Gas Flow Adjustment Ranges below
Port Size: 1/2˝ NPT
Primary Construction Material: Brass or Stainless Steel
Setting Type: Adjustable
These externally adjustable switches are ideal for protecting machine tools from
coolant flow failure, for protecting bearings from loss of lubricant or to assure proper
air flow. They offer an infinite number of flow settings at pressures up to 1000 PSIG,
with low pressure drop and precise repeatability.
The adjusting vane is easily field adjustable using an ordinary flat-bladed screwdriver.
The adjustment is set-screw-locked for tamper-free operation after field calibration.
Specifications
Wetted Materials
Housing Brass or 316 Stainless Steel
Piston
In Brass Housing Polysulfone for water; Brass for oil or air
In Stainless Steel Housing 316 Stainless Steel Only
Spring 316 Stainless Steel
O-Ring Viton®
Other Wetted Parts Epoxy
Pressure Rating
Operating 1000 PSIG (69 bar)
Proof 2500 PSIG (172 bar)
Burst 5000 PSIG (345 bar)
Operating Temperature
With Brass or S.S. Piston -20°F to +300°F (-29°C to +148.9°C)
With Polysulfone Piston -20°F to +225°F (-29°C to +107.2°C)
Repeatability 1% Maximum Deviation
Set Point Accuracy ±10% Maximum
Set Point Differential 15% Maximum
Switch* SPDT, 20 VA
Inlet/Outlet Ports 1/2˝ NPT
Electrical Termination No. 18 AWG, 24˝ L., Polymeric Lead Wires
*See “Electrical Data” on Page X-5 for more information.
Air/Gas Flow Adjustment Ranges
Water or oil flow units should not be utilized for air/gas applications. The FS-10798
Gas Flow configuration utilizes a special dash-pot piston for reliability. The flow
adjustment ranges are typical for air service. For other gases, the flow range will vary
with the density of the gas. Please consult factory for more information.
For 5 PSIG Line* 1 to 75 SCFM Approx.
For 100 PSIG Line 3 to 160 SCFM Approx.
* Minimum 5 PSI line pressure required.
U.L. Recognized — File
No. E31926
CSA Listed —
File No. LR30200
Dimensions
With Wire Leads and Strain Relief
With 1/2˝ NPT Conduit Connector
Shown with optional 1/2”
conduit connector.
G-13
FLOW SWITCHES
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Media Materials Part Numbers
With Lead
Wires
With 1/2˝
Conduit
Connector
Housing Piston
Liquids Brass Brass (for Oils) 61205 49073
Polysulfone (for Water) 25357 25363
316 Stainless Steel 25358 25364
Gases Brass 25359 25365
316 Stainless Steel 25360 25366
SPRING
HERMETICALLY SEALED
SPDT SWITCH PERMANENT MAGNET
PISTON
HOUSING VALVE ADJUSTMENT
LOCKING SET SCREW
FLOW ADJUSTMENT
VANE
PISTON
MAGNETIC SWITCH
ADJUSTMENT
Flow diagram with switch
shown actuated.
2.0
1.5
1.0
0
0.5
0 0.5 1.0 2.0
2.5
FLOW RATE - GPM
PRESSURE DROP (PSID)
Part No. 25357
12
8
4
0
0 5 10 15 20 25 30
16
FLOW RATE - GPM
Tests conducted with units in horizontal position with water at +70°F (21°C).
Data will vary slightly for vertically mounted units.
PRESSURE DROP (PSID)
Part No. 25358
PISTON TYPE
How It Works
An externally rotatable vane is positioned in the main flow path within the unit. The
magnet carrier piston is located in a bypass flow chamber. Pressure differential,
caused by flow around the adjusting vane, displaces the spring-biased piston which
actuates a hermetically sealed SPDT reed switch within the unit.
How To Order – Standard Models
Specify Part Number based on desired media, piston material and electrical termination.
Notes:
1. Temperature changes will slightly affect the standard water or gas flow settings listed.
Oil flow settings will vary with temperature and viscosity.
2. Use of 50 micron filtration is recommended.
– Stock Items.
Pressure Drop - Typical
0.5 GPM
10 GPM and 20 GPM
FS-10798 switches are U.L. Approved for Class I,
Division 2, Groups A, B, C, D hazardous locations.
U.L. Approved — File No. E183854
Wire Color Terminal
Orange N.O.
Black Common
Red N.C.
Standard Wiring Color Code
G-14
FLOW SWITCHES
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UL Approved
Explosion-Proof
1/4" (6.3 mm)
2-3/8"
(60.3 mm)
1-1/4" (31.7 mm)
3/4"
(19.0 mm)
1/4" NPT
BOTH PORTS
1-3/4"
(44.4 mm)
4-1/8"
(104.7 mm)
1"
(25.4 mm)
27/32" (21.4 mm)
9/32" DIA. (7.1 mm)
MTG. HOLES (2)
1/2" (12.7 mm)
G-11b ill
1/2"
(12.7 mm)
FS-930 Series – Oil Flow Switch,
Compensates For Viscosity Change In Fluids
Flow Rate Settings: 0.1 GPM to 1.0 GPM
Port Size: 1/4˝ NPT
Primary Construction Material: Brass
Setting Type: Fixed
A unique, patented piston design assures accuracy within 20% over a full range of
viscosities—from 40 to 1000 SSU. Ideal for use in applications where liquids of different
viscosities are blended; or for use in lubrication systems where oil flow monitoring is
critical at start-ups. Switch compensates for viscosity changes automatically. Each unit
is factory preset, using 300 SSU oil, for actuation at specified flow rates.
Specifications
Wetted Materials
Housing Brass
Piston Brass
Spring 316 Stainless Steel
O-Ring Viton®
Other Wetted Parts Epoxy
Pressure Rating
Operating, Maximum 1000 PSIG (69 bar)
Proof 2500 PSIG (172 bar)
Burst 5000 PSIG (345 bar)
Operating Temperature -20°F to + 300°F (-29°C to +148.9°C)
Repeatability 1% Maximum Deviation**
Set Point Accuracy ±10%
Set Point Differential 15% Maximum
Switch* SPDT, 20 VA
Inlet/Outlet Ports 1/4˝ NPT
Electrical Termination No. 18 AWG, 24˝ L., Polymeric Lead Wires
Explosion-Proof Approvals U.L. Approved for Class I, Division 2, Groups A, B,
C, D. Also available with FM approved, explosion
proof junction box for Class I, Division 1, Group D
hazardous locations.
U.L. Approved — File No. E183854
* See “Electrical Data” on Page X-5 for more information
** Reference at 300 SSU set point.
U.L. Recognized —
File No. E31926
Dimensions
Electrical Connection, 1/2˝ NPT Conduit
G-15
FLOW SWITCHES
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Flow Setting
GPM, ±10%
Part
Numbers
0.10 51582
0.25 51586
0.50 51590
0.75 51594
1.00 51598
4
2
1
3
0
0.1 0.5 1.0 1.5
5
FLOW RATE - GPM
PRESSURE DROP (PSID)
Part No. 51598
Part No. 51590
Part No. 51582
Tests conducted with units in vertical position (lead wires up) with water at
+70°F (21°C).
PISTON TYPE
How To Order – Standard Models
Specify Part Number based on flow setting.
Notes:
1. Flow settings are calibrated in a vertical position (lead wires up) with 300 SSU oil. Set points will
be maintained within 20% of settings in a liquid viscosity range of 40 to 1,000 SSU.
2. Use of 50 micron filtration is recommended.
– Stock Items.
Pressure Drop – Typical
G-16
FLOW SWITCHES
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LEAD WIRES
BONNET
INLET PORT
OUTLET
PORT
FS-400 Series
(Partial Cutaway)
SPRING
SHUTTLE
PERMANENT
MAGNET
OUTLET
PORT
SPRING
BONNET
LEAD
WIRES
HERMETICALLY
SEALED SWITCH
PERMANENT
MAGNET
INLET
PORT
HOUSING
SHUTTLE
HOUSING
Adjustable versions of the FS-200 and FS-400 Flow
Switches incorporate an internal adjustable bypass
vane which is controlled externally using an ordinary,
flat-blade screwdriver. As the bypass vane is rotated
to its open position, an increasing amount of liquid is
allowed to bypass the shuttle assembly, resulting in
the need for a higher rate of flow to actuate the switch;
closing the adjustable bypass vane results in switch
actuation at lower flow rates. Switch actuation can be
set from 0.75 GPM to 15 GPM.
Shuttle Type Switches –
For Moderate to High Liquid Flow Rates
Models for flow rate settings from .5 GPM to 100.0 GPM
Rugged housings with port sizes ranging from 3/4˝ NPT to 3˝ NPT
Efficient flow paths assure low line pressure drop at full flow
Typical Applications
Protect bearings or gears from loss of lubricant flow. Can reduce maintenance costs on…
• Oil separators • Fuel Systems • Pumps • Compressors • Presses
Provide instant, automatic shutdown if coolant flow falls off in electronics or machinery, such as…
• Heat Exchangers • Semiconductor Manufacturing Equipment
• Induction Furnaces • Radio Transmitters
Assure efficient operation of process systems, including…
• Water Filtration and Reverse Osmosis • Chlorinators • De-icers
• Sterilizers • Evaporators
Design Data
General Operating Principle (FS-200 Series Shown) Adjustable Versions
As liquid flow increases
to the actuation setting, a
magnet-equipped shuttle
is displaced. When
displaced by fluid flow,
this shuttle actuates
a hermetically sealed,
SPDT or SPST reed
switch within the unit
stem. A compression
spring or gravity
provides shuttle return
when flow decreases.
This reed switch, when actuated, can be used to
operate remote alarms or indicators, or may be
integrated into automatic system controls.
Typical flow diagram
showing switch actuated.
90° Flow Path Versions
Replace an ordinary 90° pipe joint with an
FS-400 Series switch to monitor liquid flow
with 1% repeatability. A choice of seven
flow rate actuation settings ranging from
0.75 GPM to 10.0 GPM are offered.
FS-200 Adjustable
(Partial view)
FS-400 Adjustable
(Partial view)
Regulating action of the bypass vane is
shown here for the FS-400 Adjustable
unit, and functions the same in the
FS-200 Adjustable versions.
Vane fully open
(high flow)
Vane fully closed
(low flow)
G-17
FLOW SWITCHES
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BONNET
HERMETICALLY
SEALED SWITCH
HOUSING
SHUTTLE
LOCKING KEYS
SLIDE OUT
TO RELEASE
BONNET
BONNET AND
SHUTTLE LIFT
OUT OF
HOUSING
HOUSING
STAYS IN
PIPING
SYSTEM
BONNET AND
SHUTTLE LIFT
OUT OF HOUSING
BONNET IS
RELEASED
WITH A
COUNTER-
CLOCKWISE
TWIST
HOUSING STAYS
IN PIPING
SYSTEM
SHUTTLE TYPE
All Plastic, Transparent Versions
The FS-400P Series is an inexpensive
alternative for plastic piping systems.
Units are available in clear PVC
housings. The clear version, with a
bright red shuttle, provides highly
visible affirmation of flow status.
Low-cost, all PVC versions are for use
in systems where liquid pressures are
below 120 PSIG and temperatures do
not exceed 120°F. An easily removed,
one-piece bonnet and shuttle assembly
for quick clean-out is featured.
Typical Bonnet and Shuttle Removal
While a slight accumulation of foreign material within shuttle type units will not affect
operation, 150 micron filtration is suggested. Any sizable amount of contamination
should be removed. Removing the bonnet nut on FS-200, and FS-400 Series units
allows the shuttle assembly to be removed for cleaning without disturbing the
installation. Sliding keys on the FS-400P are removed, or the bonnet is twisted on the
FS-500, for the one-piece bonnet/shuttle to be lifted out of its housing. Consult the
factory for replacement parts. Damaged electrical components must be replaced at the
factory.
FS-400P Series FS-500 Series
Contents Page Start
FS-200 Series
General Purpose,
Straight-Through Flow Path .....................G-18
FS-200 Series Adjustable
Externally Adjustable
Actuation Set Point .......................................G-18
FS-400 Series
General Purpose, 90° Flow Path .............G-20
FS-400 Series Adjustable
Externally Adjustable
Actuation Set Point .......................................G-20
FS-400P Series
Low-Cost, All PVC ..........................................G-21
FS-500 Series
Low-Cost, All Polypropylene ...................G-22
G-18
FLOW SWITCHES
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Model Port Size
NPT
A
inch (mm)
B
inch (mm)
C Hex
inch (mm)
FS-200
and
FS-200
Adjustable
1˝ 3-1/4 (82.6) 3 (76.2) 1-25/32 (45.2)
1-1/4˝ 4 (101.6) 3-3/16 (80.9) 2-3/16 (55.5)
1-1/4˝ ss 4-1/2 (114.3) 3-3/16 (80.9) 2-3/16 (55.5)
1-1/2˝ 4-1/2 (114.3) 3-1/2 (88.9) 2-1/2 (63.5)
2˝ 5-3/8 (136.5) 4 (101.6) 3-3/32 (78.5)
UL Approved
Explosion-Proof
A
B
1/2" -NPT
BONNET
SWITCH
HOUSING
NPT PORT
INLET PORT
C
#18 AWG., 24" L.,
POLYMERIC JACKET
G-4 ill
FS-200 Series – General Purpose,
Straight-Through Flow Path
Flow Rate Settings: Fixed: 0.5 GPM to 100.0 GPM
Adjustable: 1.0 GPM to 15.0 GPM
Port Size: 1˝ NPT to 2˝ NPT
Primary Construction Material: Bronze or Stainless Steel
Setting Type: Fixed or Adjustable
The FS-200 Series offers accurate flow detection, with 1% repeatability, over a broad
range of flow settings and port sizes. Its durable construction delivers long-life
reliability in either water or oil. Generous flow paths keep pressure drop low. These
switches are ideal for detection of improper flow rates in high volume lubrication,
cooling or process systems.
FS-200 Adjustable Series switches offer the same accuracy and are as rugged as those
with fixed settings, but provide one additional feature: external adjustability. With these
versatile switches your choice of flow settings is diverse within a given range. An
ordinary, flat-blade screwdriver is all that’s required for the actuation adjustment.
Specifications
Wetted Materials
Housing
FS-200 Bronze or 316 Stainless Steel
FS-200 Adjustable Bronze
Shuttle Teflon®
Bonnet Bronze or Stainless Steel
Spring 316 Stainless Steel
Other Wetted Parts Viton®, Ceramic
Pressure Rating
Operating 400 PSIG (27.6 bar) @ 100°F (37.8°C)
Proof 800 PSIG (55.2 bar) @ 100°F (37.8°C)
Operating Temperature
FS-200 -20°F to +300°F (-29°C to +148.9°C)
FS-200 Adjustable -20°F to +200°F (-29°C to +93.3°C)
Repeatability 1% Maximum Deviation
Set Point Accuracy ±10%
Set Point Differential 15% Maximum
Switch* SPDT, 20 VA
Electrical Termination No. 18 AWG, 24˝ L., Polymeric Lead Wires
Red NC, Black Common, Orange NO
*See “Electrical Data” on Page X-5 for more information.
FS-200 Series
U.L. Recognized
File No. E31926
CSA Listed —
File No. LR30200
and LR22666
FM Approved —
File No. 0A8A3.AE
and 1H3A2.AX
FS-200 Adjustable
U.L. Recognized
File No. E31926
CSA Listed —
File No. LR22666
FM Approved —
File No. 0Q2A8.AE
Dimensions
Notes:
1. Adjustable versions available in 1 inch port sizes only.
2. Standard calibration is in water with units in a horizontal position.
3. Viscosity changes will affect setpoints. Typically, as viscosity
increases setpoints will decrease.
4. Consult Gems for special applications.
G-19
FLOW SWITCHES
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FS-200 Adjustable
Port Size
NPT
Flow
Setting
GPM
Part Numbers
Bronze Stainless
Steel
1”
0.5 27051 27059
127052 27060
227053 27061
327054 27062
427055 27063
527056 27064
627057 27065
827058 27066
1-1/4”
127067 27076
227068 27077
427069 27078
627070 27079
827071 27080
10 27072 27081
12 27073 27082
16 27074 27083
20 27075 27084
Port Size NPT Flow Setting Adjustment Range GPM Part Numbers
1”
1.0-6.0 26615
5.0-15.0 26616
2.0-8.0 26838
Port Size
NPT
Flow
Setting
GPM
Part Numbers
Bronze Stainless
Steel
1-1.2”
1.5 27085 27093
327086 27094
527087 27095
7.5 27088 27096
10 27089 27097
15 27090 27098
20 27091 27099
30 27092 27100
2”
227101 27109
427102 27110
527103 27111
10 27104 27112
15 27105 27113
25 27106 27114
35 27107 27115
50 27108 27116
SHUTTLE TYPE
4
3
2
0
1
0 5 10 15 20 25 30 35 40
FLOW RATE - GPM
PRESSURE DROP (PSID)
1.5
1.0
0.5
0
0 10 20 30 40 50 60 70 80
2.0
FLOW RATE - GPM
Tests conducted with units in horizontal position (lead wires up) with water at
+70°F (21°C).
PRESSURE DROP (PSID)
Part No. 27101
Part No. 27085
Part No. 27051
How To Order – Standard Models
Specify Part Number for the FS-200 Series based on desired housing material, port
size and flow setting, or based on flow setting range for FS-200 Adjustable versions.
FS-200 Series
Notes:
1. Flow settings for fixed versions are calibrated using water at +70°F on increasing flow, with units in a
horizontal position (lead wires up). Consult factory regarding special flow setting calibration, or liquids other
than water. Temperature changes will slightly affect the flow settings listed. Oil flow settings will vary with
viscosity.
2. Adjustable units that are set to customer specification are subject to GEMS test stand accuracy.
3. Use of 150 micron filtration is recommended.
4. Minimum 5 PSI line pressure required.
– Stock Items.
Pressure Drop - Typical
1˝ NPT and 1-1/2˝ NPT Ports
2˝ NPT Ports
FS-200 Series Flow Switches are U.L. Approved for
Class I, Division 2, Groups A, B, C, D hazardous areas.
They are also available with FM-approved,
explosion-proof junction box for Class I,
Division 1, Group D hazardous locations.
Units must be completely assembled at GEMS.
U.L. Approved — File No. E183854
For Remote Alarms –
See Page E-30
• Adjustable Volume
• Indoor Outdoor
• Solid-State
G-20
FLOW SWITCHES
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NPT Flow Setting
GPM
Part
Numbers
3/4˝
0.75 26440
1.5 26441
2.0 26442
2.5 26443
5.0 26444
7.5 26445
10.0 26446
NPT Flow Setting
GPM
Part
Numbers
3/4˝
0.75-4.0 26600
2.0-8.0 26601
7.0-14.0 26602
UL Approved
Explosion-Proof
3-27/32"
(97.6 mm)
1-3/8"
(34.9 mm)
1-3/8"
(34.9 mm)
1/2" NPT
1-7/16" HEX
(36.5 mm)
25
15
10
5
20
0
0 5 10 15 20
30
FLOW RATE - GPM
Tests conducted with units in vertical position (lead wires up) with water at
+70°F (21°C).
PRESSURE DROP (PSID)
Part No. 26440
Part No. 26446
Part No. 26443
FS-400 Series –
General Purpose, 90° Flow Path
Flow Rate Settings: Fixed Version: 0.75 GPM to 10.0 GPM
Adjustable Version: 0.75 GPM to 14.0 GPM
Port Size: 3/4˝
Primary Construction Material: Bronze
Setting Type: Fixed or Adjustable
Provides accurate flow detection in water and oil with 1% repeatability. Flow settings
on the adjustable version can be easily changed without disassembly. A shuttle by-
pass vane inside the housing is controlled externally using an ordinary flat-blade
screwdriver. These switches are ruggedly constructed of non-corrosive materials and
resist shock and vibration. Suitable for triggering alarms on interlocking shutdown
circuitry when flow rate is improper to protect bearings, gears and cooling systems.
Specification
Wetted Materials
Housing Bronze
Shuttle Delrin®
Spring 316 Stainless Steel
O-Ring Viton®
Other Wetted Parts Ceramic
Pressure Rating, Maximum
Operating 400 PSI (27.6 bar) @ 100°F (+37.8°C)
Proof 800 PSI (55.2 bar) @ 100°F (+37.8°C)
Operating Temperature -20°F to +180°F (-29°C to +82.2°C)
Repeatability 1% Maximum Deviation
Set Point Accuracy ±10%
Set Point Differential 15% Maximum
Switch* SPDT, 20 VA
Inlet/Outlet Ports 3/4˝ NPT
Electrical Termination No. 18 AWG, 24˝ L., Polymeric Lead Wires
*See “Electrical Data” on Page X-5 for more information.
How To Order – Standard Models
Specify Part Number based on flow settings for the FS-400 Series, based on flow
setting range for the FS-400 Adjustable version.
FS-400 Series FS-400 Adjustable
Notes:
1. Flow settings for Fixed Version are calibrated using water at +70°F on increasing flow, with units in a
vertical position (lead wires up). Temperature changes will slightly affect the flow settings listed.
2. Adjustable units that are set to customer specifications are subject to GEMS test stand accuracy.
3. Use of 150 micron filtration is recommended.
4. Minimum 5 PSI line pressure required.
– Stock Items.
FS-400 Series FS-400 Adjustable
U.L. Recognized —
File No. E31926
CSA Listed —
LR30200 and LR22666
FM Approved —
File No. 0A8A3.AE and
1H3A2.AX
CSA Listed —
File No. LR22666
FM Approved —
File No. 0A8A3.AE
Dimensions
Pressure Drop - Typical
FS-400 switches are U.L. Approved for Class I,
Division 2, Groups A, B, C, D hazardous areas.
Available with FM-approved, explosion-proof junction
box for Class I, Division 1, Group D hazardous locations.
Units must be assembled completely at GEMS.
U.L. Approved — File No. E183854
G-21
FLOW SWITCHES
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PVC
Material
Port
Size
Actuation on
Increasing Flow
Part
Numbers
Clear
1/2˝ NPT* 0.5 GPM ±20% 135805
3/4˝ IPS 0.5 GPM ±20% 135810
1˝ IPS 2.0 GPM ±20% 135815
SHUTTLE TYPE
LOCKING KEYS
SLIDE OUT
TO RELEASE
BONNET
BONNET AND
SHUTTLE LIFT
OUT OF
HOUSING
HOUSING
STAYS IN
PIPING
SYSTEM
1-5/8"
(41.3 mm) DIA
3-13/16"
(96.8 mm)
1-1/2"
(38.1 mm)
BONNET
HOUSING
4-3/8"
(111.1 mm)
2-1/16"
(52.4 mm)
1
2
0
0 3 6 9 12 15 18
3
FLOW RATE - GPM
PRESSURE DROP (PSID)
Part No. 135815
Part No.135810
Tests conducted with units in vertical position (lead wires up) with water at
+70°F (21°C).
FS-400P Series – Low Cost Units for
Plastic Piping
Flow Rate Settings: 0.5 GPM or 2.0 GPM
Port Size: 3/4˝ or 1˝ IPS
Primary Construction Material: Clear PVC
Setting Type: Fixed
Designed for low cost flow/no-flow monitoring. This series is available with a clear
transparent PVC housing which is ideal for use where visual flow confirmation is
desirable. These corrosion-resistant switches offer broad chemical compatibility.
With only one moving part, their rugged construction offers long life with minimum
maintenance. Ideal for water heating or purification, equipment cooling and general
chemical processing use.
Specifications
Materials
Housing, Shuttle and Bonnet PVC
O-Ring Buna N
Other Wetted Parts Epoxy
Operating Pressure, Maximum
120 PSIG (8.3 bar) @ +70°F to +100°F
@ +21°C to +37.8°C
50 PSIG (3.4 bar) @ +101°F to +120°F
@ +38.3°C to +48.9°C
Operating Temperature, Maximum
Clear Version +120°F (+48.9°C)
Set Point Accuracy ± 20%
Set Point Differential 20% Maximum
Switch* SPST, 20 VA N.O. @ No Flow
Inlet/Outlet Ports 3/4˝ or 1˝ IPS and 1/2˝ NPT
Mounting Attitude Vertical, Inlet Down
Electric Termination No. 22 AWG, 24˝ L., PVC Lead Wires
*See “Electrical Data” on Page X-5 for more information.
How To Order – Standard Models
Specify Part Number based on material and port size.
*3/4˝ IPS model with 1/2˝ NPT port adapter installed.
Notes:
1. Care should be taken by specifiers to ensure fluid
compatibility with the above listed wetted materials.
2. Use of 150 micron filtration is recommended.
– Stock Items.
U.L. Recognized —
File No. E31926
CSA Listed —
File No. LR30200
Cleanout is quick and
easy. Two locking
keys slide out to allow
removal of a one-piece
bonnet and shuttle
assembly. Housing
and piping are left
undisturbed.
Dimensions
3/4˝ IPS Size (Both Ports) 1˝ IPS Size (Both Ports)
(All other dimensions are
the same as 3/4˝ size)
1/2˝ NPT
Pressure Drop - Typical
G-22
FLOW SWITCHES
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Switch Actuation
Set Point
GPM
Part Numbers
Pilot Duty J-Box w/5A Relay
0.25 170231 175901
0.50 170232 175902
1.00 170233 —
2.00 175117 —
2.50 170234 —
5.00 170235 —
Note: Use of 100 micron filtration is recommended.
BONNET AND
SHUTTLE LIFT
OUT OF HOUSING
BONNET IS
RELEASED
WITH A
COUNTER-
CLOCKWISE
TWIST
HOUSING STAYS
IN PIPING
SYSTEM
8
1.48"
(37.5mm)
1.8"
(45mm)
3.80"
(96.5mm)
BONNET
HOUSING
2.00"
(50.8mm)
1.32"
(33.5mm)
10
2
1
0
0 64 14 1682 12 18 20 22 24
4
3
5
FLOW RATE - GPM
Tests conducted with units in vertical position (lead wires up) with
water at +70°F (21°C).
PRESSURE DROP (PSID)
Part No. 170235
Part No. 170231
FS-500 Series – Low Cost Units for
Threaded Plastic Piping
Flow Rate Settings: 0.25 GPM to 5.0 GPM
Port Size: 3/4˝ NPT
Primary Construction Material: Polypropylene
Setting Type: Fixed
The FS-500 offers low cost flow monitoring with a variety of switch actuation points
and low pressure drop. All wetted parts are polypropylene or stainless steel, making this
switch ideal for a wide range of chemical and temperature requirements. The materials
are also NSF or FDA approved for potable water treatment applications including
chlorinators, purifiers and heaters. The FS-500 is ideal for equipment cooling
including welders, lasers, etc. A J-box version with a 5 amp relay is also available for
direct control of higher electrical loads, such as chlorinator pumps.
Specifications
Wetted Materials*
Housing, Bonnet, Shuttle, Shuttle Cap Polypropylene, Hydrolytically Stable
O-Ring Viton® or Buna N
Spring 316 Stainless Steel
Retaining Clip PH 15-7 Mo Stainless Steel
Operating Pressure, Maximum 100 PSIG (6.9 bar) @ +70°F (21°C)
50 PSIG (3.4 bar) @ +180°F (82°C)
40 PSIG (2.8 bar) @ + 212°F (100°C)
Operating Temperature, Maximum 0° to 212°F (100°C)
Set Point Accuracy ± 20%
Set Point Differential ± 20% Maximum
Switch** SPST, N.O. Pilot Duty 20 VA, 120-240 VAC or VDC
J-Box with 5A Relay
Coil 120 VAC 50/60 Hz
Contacts SPDT 5A – 240 VAC Res
1/3 HP – 120 VAC
5A – 28 VDC Res.
Inlet/Outlet Ports 3/4˝ Female NPT
Electric Termination
Pilot No. 22 AWG, 24˝ Zip Cord Lead Wires
J-Box 6´ PVC Cable
* Materials of Construction are available for FDA or NSF Compliance.
** See “Electrical Data” on Page X-5 for more information.
How To Order – Standard Models
Specify Part Number based on switch actuation set point. Set points other than
those listed are available as special order; contact GEMS with your requirements.
Normally closed switch logic units available as special orders.
– Stock Items.
FS-500
Series
J-Box with
5-Amp Relay
Dimensions
Pressure Drop - Typical
File No. E31926
G-23
FLOW SWITCHES
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11
2
2"
21
2
3"
"
"
HOUSING
AND STEM
ASSEMBLY
HERMETICALLY
SEALED
SPDT SWITCH
SPRING
PERMANENT
MAGNET
SPACER
SHUTTLE
PADDLE
AND CAM
ASSEMBLY
10"
8"
3"
1 1/4"
.66" (16.7 MM) MAX. HEIGHT
OF BOSS FROM PIPE OR
TEE I.D.; FOR PROPER
OPERATION OF SWITCH,
DO NOT EXCEED .66" (16.7 MM).
.66" (16.7 MM)
RECOMMENDED PIPE
IS SCHEDULE 40
FLOW
1" NPT BOSS
PADDLE TYPE
Paddle Type Flow Switches – For Flow/
No-Flow Detection in Large Line Sizes
Engineered for positive liquid flow detection at pressures to
2000 PSIG (138 bar)
Unique, patented cam design assures low pressure drop
and does not require bellows, seals, or mechanical linkages
Minimum in-line restriction; paddle pivots to move out of liquid path
with increasing flow
Typical Applications
Assure flow and/or leak detection in large, high pressure in...
• Compressors • Heat Exchangers • Turbines • Engines • Boilers • Chillers
Protect high or low pressure pumps from cavitation, sense critical, reverse flow and
protect...
• Valves • Pumps • Regulators
Design Data
General Operating Principle
De-actuated (no-flow) Actuated (flow)
Liquid flow in either direction deflects the paddle which, by cam
action, displaces a permanent-magnet-equipped shuttle along the
unit stem. The magnet actuates a hermetically sealed, magnetic
reed switch within the stem to operate a remote alarm or indicator.
Paddles Cut-to-Length For Broad Range of Pipe Sizes
Cutting the paddle to length selects a standard flow rate as shown on the tables on the
following pages. Approximate pipe sizes are marked on the paddle. These units can be
used in pipe with diameters greater than the 5˝ paddle length. They provide flow/
no-flow detection where there is a velocity of 0.5 ft. per second.
Simple Installation and Easy Maintenance
Installs in a standard pipe tee or reducing fitting. If
excessive particle build-up necessitates occasional
cleaning, simply remove the unit and manually remove
particles actuate paddle for free movement.
Easy Installation
Installs in a standard pipe tee
or reducing fitting.
Contents Page Start
FS-550 Series
High Pressure, Metal Version ..................G-24
G-24
FLOW SWITCHES
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Pipe Size
Marked
at Paddle
Cut-Off
Point
Pipe Line Sizes
1-1/4˝ 1-1/2˝ 2˝ 2-1/2˝ 3˝ 4˝
Approximate Actuation and (De-Actuation) Flow Rates
GPM Water
Short
Paddle Unit 1-1/4˝ 5 (3) 13 (8) 22 (15) 29 (22) — —
Long
Paddle Unit
1-1/2˝ — 15 (11) 28 (21) 38 (30) — —
2˝ — — 22 (15) 27 (20) 48 (38) —
2-1/2˝ — — — 21 (14) 40 (26) 52 (39)
3˝ — — — — 31 (20) 45 (32)
4˝ — — — — — 39 (25)
Switch
Type
Paddle
Length
Housing
Material
Switch
Operation
Part Numbers
Standard 3-Pin J-Box
SPDT
Standard
Unit
Long Brass
N.O.
or
N.C.
29609 56730
316 S.S. 29608 56729
Short Brass 30641 66914
316 S.S. 30640 61189
1-1/2
"
2
"
2-1/2
"
3
"
3-7/16"
(87.2 mm)
5-1/2"
(139.7 mm)
1"
(25.4 mm)
1-1/2" -3"
(LONG)
PADDLE
1" NPT
1/2" NPT
1"
1-11/16"
(42.8 mm)
1-1/4"
(SHORT)
PADDLE
1"
(25.4 mm)
1-1/2"
2"
2-1/2"
3"
LOAD
VAC
SAFE-PAK
FS-550
SWITCH
HAZARDOUS
AREA
FS-550 Series – High Pressure, Metal
Paddle Switch
Pipe Line Size: 1-1/4˝ and Up
Primary Construction Material: Stainless Steel or Brass
Setting Type: Fixed
Standard FS-550 switches sense liquid flow in either direction to monitor flow/no-flow
conditions. They are supplied in two paddle lengths. The paddle is trimmed during
installation to permit switch actuation at the desired flow rate. As flow increases in
a pipe, the paddle of the switch pivots to move out of the liquid path, producing less
than 3 PSIG of pressure drop regardless of pipe size.
Specifications
Wetted Materials
Housing Brass or 316 Stainless Steel
Paddle 302 Stainless Steel
Spring 316 Stainless Steel
Other Wetted Parts Ceramic and Teflon®
Operating Pressure, Maximum 2000 PSIG (138 bar)
Pressure Drop 3 PSIG (0.2 bar) Maximum
Operating Temperature -30°F to + 300°F (-34.4°C to + 148.9°C)
Set Point Accuracy ± 25%
Switch* SPDT, 20 VA
Repeatability ± 5%
Electrical Termination No. 18 AWG, 24˝ L., Polymeric Lead Wires
*See “Electrical Data” on Page X-5 for more information.
Standard Actuation and De-actuation Set Points
The Table below indicates paddle lengths which achieve switch actuation for specific
flow rates. Approximate pipe line sizes are marked on paddle.
All flow rate tests for the above table were conducted with the switch installed in a
standard “T” fitting. For calculation of flow rates in pipe sizes larger than 5˝, a flow
velocity of approximately 0.5 ft. per sec. actuates the switch with a full length (5˝ )
paddle. The paddle can be trimmed to achieve different actuation points.
How To Order – Standard Models
Select switch type, paddle length and housing material, then specify adjacent part
number.
Note: The FS-550 Switch is not recommended for use with 1˝ plastic tees.
U.L. Recognized
File No. E31926
CSA Listed —
File No. LR30200
and LR22666
FM Approved —
File No. 0A8A3.AE
and 1H3A2.AX
Dimensions
FS-550 switches are U.L. Approved for Class I,
Division 2, Groups A, B, C, D hazardous areas.
They are also available as FM-approved
when used with GEMS Junction Boxes
which are explosion-proof for Class I,
Division 1, Groups B, C, D, E, F, G hazardous
locations.
Using GEMS SAFE-PAK
Relays and barriers,
these switches provide
automatic flow/no
flow interlock and
are intrinsically-safe
without explosion-proof
housing and piping.
U.L. Approved — File No. E183854