Murphy L150 / EL150K1 Level Swichgage for Engine Liquids

Float-type level gauge with a low-limit switch for engine cooling systems

The Murphy L150 / EL150K1 Level Swichgage is a combined liquid level gauge and low-limit switch. Each unit contains a chamber with a pivoting float, an indicating dial with pointer and a low-level contact. When properly installed and maintained, the float moves the pointer, which shows level in normal operation and closes a switching circuit if the level falls to the low-limit set point.

Enovation Controls lists the primary use as engine cooling systems, surge or expansion tanks, condenser radiator or vapor phase systems, whether pressurized or atmospheric. The unit can also monitor lube oil, hydraulic fluid or diesel fuel reservoirs and trigger an alarm or shutdown at a predetermined minimum level. It is built for low pressure systems with a maximum of 25 psi (172 kPa, 1.72 bar).

Technical specifications

Values are from Enovation Controls bulletin 00072. The bulletin gives three columns, one for each model.

Three models in one bulletin

The L150 uses a simple contact rated 2 A at 30 VAC/DC. The EL150K1 replaces it with an SPDT snap switch and a higher electrical rating, in a case with a rating of IP35. The EL150EX is the hazardous-location version with a sand cast aluminum case, a stainless steel float and a CSA listing for Class I, Division 1, Groups C and D.

The How to Order table lists repair kits for each model (complete assemblies without the case and body, the case and body assembly, lens and switch, cover and float, lid and switch or terminal assemblies, depending on the model). Murphy PS, PS Barbed and PS-D radiator fittings are listed for mounting the L150 or EL150K1 when the radiator has no fitting; PS-D is the thick-wall version for diesel or oil.

Installation notes and what to confirm

Mount the unit so the float chamber is in contact with the liquid whose low level you want to detect, and connect the vent tube according to the system. Wiring diagrams in the bulletin are typical and shown for clarity only; they are not installation instructions. A visor kit that acts as a knob guard is listed as an EL150K1 accessory.

Confirm which model you need, the fluid and operating temperature, whether the area is hazardous, the supply voltage and the fitting at the tank or radiator. Compare the 25 psi limit with your system pressure before choosing. Enovation Controls lists this product family on its Legacy Products page, which describes those items as less popular or outdated but still available for purchase. Confirm current availability and any replacement part before ordering.

Documents and quotation

The attached bulletin 00072 (revision 2016/08/24) is the source for the values above. Seven Star LLC supplies Murphy products as an independent supplier in Muscat. Send the model, fluid, temperature and electrical requirements with your enquiry. Related products are listed under level instrumentation.