Murphy LM300 Level Switch

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The LM300 Series Level Maintainer automatically adds oil to the crankcase as needed to keep the lube level normal. Most models have built-in switches that will alarm and/or shut down the equipment if the makeup supply is depleted and engine oil level falls or if overfill conditions exist. The LM300 can be used in engines, compressors, pumps and coolers.

  • The LM300 Series EX models (explosion-proof) are CSA certified for Class I, Division 1 Hazardous areas.
  • Technical Data

Murphy SKU:ex-13957 Category: Tags: , Brand:

Available on backorder


    • Maintains proper lube level
    • Shutdown on low level, or high and low level
    • Low level alarm before shutdown
    • Manual float switch test
    • High visibility “Frog Eye” lens
    • Optional pipe or universal mounting brackets
    • Optional inlet orifices for low to high pressure applications
    • Explosion-proof models available

Additional information

Weight3.4 kg

Case/Cover: Die cast aluminum Switch Housing: Aluminum Approval Rating: All CSA Certified with switch contacts rated at 10 A at 250 VAC (standard) LM301 through LM305: CSA certified for non-hazardous locations. Enclosure Type 4 certified LM301-EX through LM305-EX: CSA certified for Class I, Groups C and D; Class II, Groups F and G hazardous locations. Enclosure Type 4 certified. Float: Rigid polyurethane foam; Polyurethane coated Max. Ambient Temperature: 250° F (121° C) Oil Inlet Connection: Top entry 1/2-14 NPT with built-in filter screen (removable for cleaning) Inlet Orifices: 1/4 in. (6 mm) standard; 1/8 in. (3 mm) available Wire (switch models): 18 AWG x 13 in. (1.0 mm2 x 330 mm) Max. Inlet Pressure (MIP): 30 psi (207 kPa) [2.07 bar] with 1/8 in. (3 mm) orifice 15 ft oil (4.6 m oil) with 1/4 in. (6 mm) orifice Max. Differential: 2 in. (51 mm) between running and stationary oil level Max. Case Pressure (MCP): 15 psi (103 kPa) [1.03 bar] Orifice Seal: Buna-N Thumb-Valve Switch Contact: Silver, SPDT snap-acting, rated at 10 A @ 125, 250 VAC; 10 A @ 30 VDC (1 only for low level; 2 only for high and low; or 2 only for low level with alarm before shutdown) Outlet Connection: 3/4-14 NPT left side, right side and bottom Crankcase Balance Vent Fitting: 1/2-14 NPT Mounting: Accepts Murphy pipe or universal mounting brackets Lens: Clear Frog Eye non-staining, high-impact, high-temperature nylon; UV and heat stabilized Glass Lens: Available on LM301 and LM301-EX models. Specify GL as part of model number when ordering Dial: High visibility white background with green and white index lines for normal level indication Test Knob: Rotate to test switch operation. Turn clockwise for low level test and turn counterclockwise for high level test.