Single Stage Liquid Level Switches in Housings are designed to shut down machinery or turn on warning devices when the liquid supply fails or recedes to a predetermined level.  They can be wired to flash a warning light, sound a howler, shut down a machine, or signal a computer.  This is especially helpful in unattended automated plants.  The units can be used with large bearings, gear cases, transformers, circuit breakers, oil tanks, and cutting oil reservoirs on screw machines, along with many other applications.  

This Liquid Level Switch is housed in a clear acrylic reservoir with aluminum alloy end plates and Buna-N seals.  The unit is mounted on the outside of the reservoir.  The stainless steel switch inside the housing should be aligned at the height where low liquid level is a concern.  The low level actuation point is measured from the center of the lower 1/2” female NPT inlet.  The low level actuation point for water is 2 5/32”, oil is 2 ¼”, and spirits is 2 7/16”. 

The bottom inlet is connected to the reservoir, and the unit is vented into the reservoir’s air supply with the ½” female NPT top outlet.  When the liquid in the reservoir recedes to the low level, a magnet carried inside of the stainless steel float actuates a reed switch within the central pipe.  The normally closed design means the contacts open with the descending liquid level.

The distance between centers of the mounting holes is 4 3/8".  This unit tolerates temperatures up to 170° F.  The overall height of the unit is 6 3/8." The largest diameter of the unit is 3 3/8".

For best results use the switch with Oil Rite relay A3154.  If the switch is used without the suggested Oil-Rite relay, be sure to keep the switch load within the resistive load rating, as follows:

For additional installation, maintenance, and electrical information, reference the “Liquid Level Switches” document located on the right hand side of this page.