Series FS Flowmeter with Flow Limit Switch

Series FS Flowmeter with Flow Limit Switch

Series HFO In-Line Flow Alarms

Latching Alarm Capabilities, For Air, Water or Caustic Fluids, Unrestricted Mounting

The Series HFO In-Line Flow Alarms provide continuous monitoring and control of flow rate levels. The flow alarm can be configured to open or close a contact for an increasing or decreasing set point. Available in 1/4", 1/2", 1" or 1-1/2" female NPT process connections, in aluminum, brass or 304 SS body.

California Residents: Click Here for Proposition 65 WARNING.

Product Applications

  • Waste water processing
  • Lubrication systems
  • Process control
  • Solar systems
  • Drain lines
  • Pump testing
Starting at $808.00
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Grouped product items
Model Description Availability* Qty Price
HFO-21112 In-line flow alarm, range 1.5-12 SCFM air, 1/4" female NPT. 3-4 Weeks*
HFO-21123 In-line flow alarm, range 4-23 SCFM air, 1/4" female NPT. 2-3 Weeks*
HFO-22205 In-line flow alarm, range 0.5-5.0 GPM (1-19 LPM) water, 1/2" female NPT. 2-3 Weeks*
HFO-22315 In-line flow alarm, range 1-15 GPM (3.8-55 LPM) water, 3/4" female NPT. 4-5 Weeks*
HFO-22320 In-line flow alarm, range 2-20 GPM (7.5-75 LPM) water, 3/4" female NPT. 2-3 Weeks*
HFO-22440 In-line flow alarm, range 4-40 GPM (15-151 LPM) water, 1" female NPT. 2-3 Weeks*
HFO-22550 In-line flow alarm, range 5-50 GPM (19-189 LPM) water, 1-1/2" female NPT. 2-3 Weeks*
HFO-23202 In-line flow alarm, range 0.2-2.0 GPM (0.75-7.5 LPM) water, 1/2" female NPT. 2-3 Weeks*
HFO-23210 In-line flow alarm, range 1-10 GPM (3.8-38 LPM) water, 1/2" female NPT. 2-3 Weeks*


Compatible gases or liquids.
Wetted Materials:
Body: Aluminum, brass or 304 SS; Seals: Buna-N or fluoroelastomer; Magnet: PTFE coated Alnico; Other internal parts: 304 SS.
500 SSU.
Temperature Limits:
170°F (76°C).
Pressure Limits:
Aluminum Body: 600 psig (41 bar); Brass body: 3500 psig (240 bar); 304 SS body: 6000 psig (413 bar).
Enclosure Rating:
NEMA 4X (IP66).
±2% FS.
±1% of FS.
Switch Type:
SPDT, 10A @ 250 VAC; 0.5A @ 125 VDC (resistive).
Shipping Weight:
1/4 to 1/2" female NPT models: 3 lb (1.4 kg); 3/4 to 1" female NPT models: 4.5 lb (2.0 kg); 1-1/2" female NPT models: 12 lb (5.4 kg).


  • Provides two 10 A SPDT limit switches with field adjustable alarm settings for application control and integral direct reading scale provides local indication of flow rate
  • Increased application versatility with no inlet or outlet straight plumbing requirement and can be mounted horizontally, vertically, or inverted
  • Outdoor or harsh environment installation capable with rugged cast aluminum construction and NEMA 4X (IP65) enclosure

Product Literature


Catalog Pages

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Model Description Availability* Price