FW Murphy LM500/LM500-TF Lube Level Maintainer

Product Overview

The LM500 maintains oil level on any size engine. It also supports installations that require a three-wire, snap-action switch. The form C (three-wire) contact allows a controller/annunciator to be wired as a closed-loop system, resulting in a reliable fault-sensitive circuit. Refer to LM500 Series Flow Rate Chart for application data.

The FW Murphy LM500-TF Oil Level Maintainer includes a test feature that confirms both the float and switch are operating correctly with a single press of the test button. The LM500 series maintains the crankcase oil level of an engine, pump or compressor. Adjusted to the correct running oil level, it will replenish oil as it is used. The low-level switch will alarm and/or shut-down the equipment, if supply oil is lost and the equipment continues to use oil.

As crankcase oil level drops, the LM500 float also drops and opens the thumb valve. This allows oil to flow from the supply tank through the LM500 and into the crankcase. When proper level is achieved in the crankcase, the LM500 float rises causing the thumb valve to close off further oil flow.

The simple and unique thumb valve is non-clogging and provides a positive, leak-free seal.

If the clean oil supply is depleted and oil level continues to fall, the low-level switch will operate an alarm or equipment shutdown.

Specifications

• Crankcase Balance Vent Connection: 1/2 NPTF (top)
• Inlet Connection: 1/2 NPTF removable screen (side)
• Outlet Connection: One connected, two not used (plugged)
• Outlet Ports: 2 x 3/4 NPTF (side), 1 x 3/4 NPTF (bottom)
• Thumb Valve Material: Viton
• Snap-switch: SPDT rating 10 A, 125 VAC; 0.5 A, 125 VDC; 10 A, 30 VDC
• Wire leads: 18 AWG x 14 in. ± 2 in. (355 mm) length
• Conduit Connection: 1/2 inch conduit (female, top)
• Case: Die cast aluminum
• Lens: Clear Frog Eye non-staining, high-impact, high temperature polycarbonate; UV and heat stabilized
• Dial: High visibility white background with solid green band for normal level indication
• Maximum Inlet Pressure: 9.50 psi/25 ft. oil (head pressure)
• Maximum Case Pressure: 15 psi (103 kPa)
• Maximum Differential: 2 in. (51 mm) between running and stopped
• Maximum Ambient Temperature: 250°F (121°C)
• Float: 304 Stainless Steel
• Flow Rates: Refer to LM500 Series Flow Rates chart for application data
• Dimensions: Overall 6-9/16 in. (H) x 6-3/16 in. (W) x 3-1/2 in. (D)
• LM500/LM500-TF Shipping Dimensions: 9.5 (W) x 7.5 (D) x 11 in. (H) (241.3 (W) x 190 (D) x 279.4 mm (H))
• LM500/LM500-TF Shipping Weight: 3 lbs. 7 oz (1.57 kg)

Diagrams and Dimensions

LM500 Dimensions:

The LM500 has a height of approximately 5-29/32 inches (149 mm), a width of approximately 4-1/8 inches (104 mm), and a depth of approximately 4-29/32 inches (124 mm). It features a 1/2-14 NPT electrical conduit connection at the top, a 1/2-14 NPT oil inlet on the side, and three 3/4-14 NPT outlet ports (one connected, two plugged).

LM500-TF Dimensions:

The LM500-TF has a similar width of approximately 4-1/8 inches (104 mm) and depth of approximately 4-29/32 inches (124 mm). Its height is approximately 6-35/64 inches (166 mm). It also features a 1/2-14 NPT electrical conduit connection at the top, a 1/2-14 NPT oil inlet on the side, and three 3/4-14 NPT outlet ports.

Thumb Valve Operation:

The diagram illustrates the thumb valve operation. When the oil level is high, the float is up, keeping the thumb valve closed. When the oil level drops, the float drops, opening the thumb valve and allowing oil to flow from the inlet to the LM500 case. When the correct level is reached, the float rises, closing the thumb valve.

LM500 Series Flow Rates Chart:

A chart shows oil flow rates in gallons per hour (GPH) versus temperature in degrees Fahrenheit (°F). The graph indicates that flow rate increases with temperature, ranging from approximately 0.5 GPH at 0°F to 3.5 GPH at 130°F.

Low Level Switch:

A diagram shows the wiring for the low-level switch, indicating Normally Closed (NC - red wire), Common (COM - white wire), and Normally Open (NO - black wire) connections.

Typical Installations

Pipe Mount:

For vented crankcases, use the plastic vent plug or an optional vent tube kit. For sealed systems, the vent must be piped back to the crankcase, above the oil level. The diagram shows the LM500 mounted via a pipe bracket, with oil inlet from a supply tank and outlet to the crankcase. Electrical conduit connects to the switch.

Universal Mount:

The universal bracket allows for various mounting methods. The diagram shows the LM500 mounted using this bracket, with oil inlet and outlet connections similar to the pipe mount. It also shows the test button and electrical conduit connection.

FW Murphy offers two mounting brackets for the LM500: a pipe bracket that fits a 7/8 in. (22 mm) diameter pipe, and a universal bracket for various mounting methods. For exact dimensions, visit http://www.fwmurphy.com.

How to Order

Options are available for the LM500 series. Configurations may vary. Contact your sales representative or FW Murphy for more information.

Model Configuration:

• Variant: LM500 (Standard), LM500-TF (Test Feature)
• Mounting Options: Blank (None), UB (Universal Bracket), PM (Pipe Mount)

Part Numbers and Descriptions:

Approximate Shipping Weight and Dimensions: