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Installation Instructions for
L971 Series Crankcase Level Switch
L-94071N
Revised 09-97
Section 15
(00-02-0173)
Description
The Murphy L971 Series Level Switch detects low oil level in a com-
pressor’s crankcase. It is designed for Ingersoll-Rand Type 30, Type 40
and ESH compressors, yet can be adapted to fit other compressors that
have an inspection plate extending below normal operating oil level.
The L971 has a 1/2 NPT process connection and features an explosion-
proof enclosure, durable SPDT snap-switch and rigid polyurethane
foam float.
Specifications
Operating Temperature: -15 to 275°F (-26 to 135°C).
Maximum Working Pressure: 30 psi (206 kPa) [2.06 bar].
Switch Rating: 4 A @ 250 VAC.
Material
Case: Aluminum (explosion-proof).
Mounting Adaptor: Brass.
Floats:
• Rigid polyurethane.
• 304 stainless steel (L971-C only).
Other Wetted Parts: 303, 304, and 316 stainless steel.
O-Ring Seals: Viton and Buna.
Process Connection: 1/2 NPT.
Enclosure Rating: UL and CSA listed for Class I, Groups C & D;
Class II, Groups F & G, Hazardous Locations.
Conduit Connection: 1/2 NPT.
Wire: 18 AWG (0.75 mm
2
).
Please read the following information before installing. A visual inspection of this product for damage during shipping is recom-
mended before mounting. It is your responsibility to have a qualified person install this unit and make sure it conforms to local codes.
GENERAL INFORMATION
WARNING
BEFORE BEGINNING INSTALLATION OF THIS MURPHY PRODUCT
✔ Disconnect all electrical power to the machine.
✔ Make sure the machine cannot operate during installation.
✔ Follow all safety warnings of the machine manufacturer.
✔ Read and follow all installation instructions.
R
Dimensions
ABCDE
L971 2-5/8 (67) 5-7/8 (149) 30 (762) 2-1/2 (64) 2-27/32 (72)
L971-A 2-5/8 (67) 5-7/8 (149) 30 (762) 2-1/2 (64) 2-27/32 (72)
L971-B 4-13/16 (122) 8-1/16 (205) 30 (762) 4-5/8 (117) 2-27/32 (72)
L971-C 2-13/16 (71) 6-1/16 (154) 30 (762) 2-7/8 (73) 3-1/8 (79)
L971-D 3-7/8 (98) 7-1/8 (181) 30 (762) 3-3/4 (95) 2-27/32 (72)
L971-E 4-13/16 (122) 8-1/16 (205) 30 (762) 5-1/8 (130) 2-27/32 (72)
L971-F 2-5/8 (67) 5-7/8 (149) 40 (1016) 2-1/2 (64) 2-27/32 (72)
L971-G 2-5/8 (67) 5-7/8 (149) 40 (1016) 2-1/2 (64) 2-27/32 (72)
*Millimeter dimensions are shown in parenthesis ( ).
Dimensions in inches
*
(see drawing above)
Models
D
A
Float arm is
adjustable but
cannot be
removed.
1/2 NPT
Float is removable
and replaceable
3 in.
(76 mm)
1/2 NPT
BC
E
**Products covered by this literature comply with EMC Council directive 89/336/EEC regarding electromagnetic compatibility except as noted.
**
L-94071N page 1 of 2
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