Murphy Level Maintainer with Two Switches DPST and 1/4 in. Orifice - Normally Closed - LM303

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2.00 LBS
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Special Order (ships approximately 2-3 Weeks)
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The Murphy Level Maintainer with Two Switches DPST LM303 automatically adds oil to the crankcase as needed to keep the lube level normal. This model has a built-in switch that will alarm and/or shutdown the equipment if the makeup supply is depleted and engine oil level falls or if overfill conditions exist. NOTE: Friction losses due to piping NOT considered.

Applications: Engines • Compressors • Pumps • Coolers



  • Maintains proper lube level
  • Shutdown on low level, or high and low level
  • Manual float switch test
  • High visibility “Frog Eye” lens
  • Two switches for low and high level shutdown or alarm. Four wires, DPST, wired N.C. (Normally Closed) in normal operating ranges
  • CSA certified with switch contacts rated at 10 A at 250 V AC (standard)



  • Part No.: LM303
  • Case/Cover: Die cast aluminum
  • Switch Housing: Aluminum
  • Approval Rating: CSA certified for non 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); Pressure: 4 ft. oil – 15 ft. oil (1.2 m oil – 4.6 m oil); Flow Rates: 4.7 GPH - 31.0 GPH (17.8 LPH - 117.3 LPH)
  • Wire (switch models): 18 AWG x 13 in. (1.0 mm2 x 330 mm)
  • Max. Inlet Pressure (MIP): 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)
  • Flow Rate Test: Using SAE 30 @ 32°F (0°C)
  • Outlet Connection: 3/4-14 NPT left side, right side, and bottom
  • Crankcase Balance Vent Fitting: 1/2-14 NPT
  • Mounting: Accepts Murphy pipe mounting bracket or universal mounting bracket
  • Lens: Clear “Frog Eye” non-staining, high impact, high temperature nylon; UV and heat stabilized
  • 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
  • Shipping Weight: 6 lbs. 6 ozs. (2.89 kg)
  • Shipping Dimensions: 10-5/8 x 8-7/8 x 6-3/4 in. (270 x 225 x 171 mm)

Product Condition: NEW
Murphy Level Maintainer with Two Switches DPST for Low and High Level Shutdown or Alarm LM303

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