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Model LR857

Eliminates Under/OverFill Due to
“Human Error”

Simple Installation

Automatically Maintains Lube Level

Low Level Switch

Models to Fit Varied Applications

Positive Sealing Thumb-Valve

LR857

Description

Murphy LR857 Lube Level Regulator maintains
the crankcase oil level of an engine, pump or
compressor. Adjusted to the correct

running-oil-

level

, the LR857 will replenish oil as it is used. An

integral, low-level switch will alarm and/or shut-
down the equipment if supply oil is lost and the
equipment continues to use oil.

Application

The LR857 maintains oil level on any size engine,
but is recommended for small to medium volume
applications and installations that require a 3-wire,
snap-action switch.

How the LR857 
Maintains Levels

As crankcase oil level drops, the LR857 float also
drops and opens the Thumb-Valve.™ This allows
oil to flow from the supply tank, through the
LR857, and into the crankcase. When proper
level is attained in the crankcase, the LR857 float
rises, causing the Thumb-Valve to close off fur-
ther oil flow.

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

Flow rate through the 

1

/

8

inch (3 mm) orifice is

significant to allow crankcase refill through 
the LR857.

Specifications

Inlet Connection:

5/8 in. (16 mm) I.D. hose

Outlet Connection:

3/8 NPT

Snap-switch:

SPDT rating 10 A @ 125 VAC; 

0.5 A @ 125 VDC; 10 A @ 30 VDC.

Conduit Connection:

1/2 NPT

Case:

Die cast aluminum

Lens:

Polycarbonate

Float:

Brass

Flow Rates (see chart below):

Oil with 0.9 specific gravity @ 70°F (21°C) 

Thumb-Valve Operation

As the equipment uses oil, the float falls, provid-
ing immediate level compensation. At FULL
position, the float holds the valve closed. If the
clean oil supply is depleted and oil level contin-
ues to fall, the low level switch will operate an
alarm or equipment shutdown.

Fittings Kit: 15000420

The 15000420 kit is sold separately. It includes
the following items.

Quantity

Description

1

1/4 in. (6 mm) O.D copper cane 
tube (vent connection)

1/4 in. (6 mm) tube x 1/4 male 
pipe fitting

1

1/2 in. (13 mm) I.D. hose fitting 
(outlet connection)

Warranty

A limited warranty on materials and workmanship is
given with this FW Murphy product. A copy of the
warranty may be viewed or printed by going to
www.fwmurphy.com/support/warranty.htm

0       

05

10

15

20

25

0

Flow: 
USGPM

Head Pressure–Feet of Oil

Head Pressure–psi

0 psi

9.73 psi

0.2500 0.5000

COM.

N.O.

Low Level
Switch

LR857
Case

Float

Action

Oil Inlet

Thumb-Valve™

FULL

LOW

N.C.

Simplified Drawing of
Thumb-Valve Operation

**Products covered by this bulletin comply with EMC Council  directive 89/336/EEC regarding electromagnetic compatibility except as noted. 

**

LR-7225B

Revised 03-05

Catalog Section 15

(00-02-0063)

Maintain Lube Level

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