G-24
FLOW SWITCHES
Visit www.GemsSensors.com for most current information.
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
