McDonnell & Miller manufactures the Series FS251 (NEMA1 version) and FS254 (NEMA4 version) general purpose liquid flow switches. These flow switches provide flow-rate sensing of 2.2 fps in 1" horizontal pipe installations, with 1", 2", 3" and 6" stainless steel paddles standard and boiler ratings of 250 degrees Fahrenheit and 160 psig. Housing materials differ: the FS251 has a stamped sheet steel base with glass reinforced polycarbonate cover, and the FS254 has a cast aluminum base and cover.

Kurz Instruments offers the Olympia 6500 Gold, 6300 Silver, and 6100 Bronze flow switches, all of which come with a 4-20 mA output and all digital design. The Gold is configurable for flow, level, and interface applications, and suitable for use with air, gas, water, liquiids, hydrocarbons, and slurries; in addition, capability to configure and monitor remotely comes standard, as do dual SPDT relay contacts and adjustable setpoint deadbands. The Silver and Bronze models are similar, but come with fewer features and more basic electronics modules.

Industrial Dynamics is a distributor of various flow rate monitors, switches, and other related products that are manufactured by various companies, including Universal Flow Monitors, Neptune, Actaris, and others.

Johnson Controls designs standard flow rate and low flow rate SPDT switches for use on liquid lines using water, ethylene glycol solutions, and other non-hazardous fluids. The switches feature an adjustment range of 0.6 GPM to 9 GPM, and NEMA 1 or NEMA 3R enclosures. The company also produces an airflow SPDT switch that detects air flow or the absence of air flow in ducts. Switch specifications include maximum ambient operating temperature of 100F, and maximum air velocity of 10 m/sec.