Murphy L971 User Manual

L971 Series

■

Durable Low Level Switch

■

Replaces Non-Explosion-proof Switch on
Ingersoll-Rand Compressors

■

Adaptable to Other Compressors

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Installs with Minimal Downtime

■

Two Year Limited Warranty

Description

The Murphy L971 Series Level Switch detects
low oil level in a compressor’s crankcase.
As oil level in the crankcase depletes, the
float on the L971 switch falls, and if reaches
the predetermined limit, will trip the internal
snap-switch which in turn will initiate a
shutdown and/or alarm.

The L971 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 explosionproof enclosure,
durable SPDT snap-switch and rigid
polyurethane foam float. A 304 stainless steel
float is available on certain configurations (see
Specifications).

Specifications

Operating Temperature Range:

-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 available on 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

).

Shipping Weight: 1 lb. 10 oz. (0.7 kg).

Shipping Dimensions: 8-1/4 x 4-1/4 x

4-1/2 in. (210 x 108 x 114 mm).

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.

R

Wiring Diagrams

*

Model L971-A

All Other Models

*Shown in “shelf” position with no force acting upon float.

**Products covered by this bulletin comply with EMC

Council directive 89/336/EEC regarding electromagnetic
compatibility except as noted.

**

L-7229B

Revised 02-97

Catalog Section 15

(00-02-0059)

Crankcase Level Switch

Green

Yellow

Green

Yellow

Red

Black

Red

To order the L971 Series Level Switch to fit your application, use the diagram below.
Example model number: L971-C

L971 – ____

How to Order

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 right)

Models

Case/Float Configuration (see chart below)

Blank = Standard configuration
A = Configuration A
B = Configuration B
C = Configuration C

D = Configuration D
E = Configuration E
F = Configuration F
G = Configuration G

L-7229B page 2 of 2

CONTROL SYSTEMS & SERVICES DIVISION

P.O. Box 1819; Rosenberg, Texas 77471; USA
[phone] fax [phone]

e-mail [e-mail]

MURPHY DE MEXICO, S.A. DE C.V.

Blvd. Antonio Rocha Cordero 300, Fracción del Aguaje
San Luis Potosí, S.L.P.; México 78384
[phone] fax [phone]
Villahermosa Office [phone]
e-mail [e-mail]
www.murphymex.com.mx

FRANK W. MURPHY, LTD.

Church Rd.; Laverstock, Salisbury SP1 1QZ; U.K.
[phone] fax [phone]
e-mail [e-mail]
www.fwmurphy.co.uk

MURPHY SWITCH OF CALIFORNIA

41343 12th Street West
Palmdale, California 93551-1442; USA
[phone] fax [phone]
e-mail [e-mail]
www.murphyswitch.com

In order to consistently bring you the highest quality, full featured products, we reserve the right to change our specifications and designs at any time.

MACQUARRIE CORPORATION

1620 Hume Highway
Campbellfield, Vic 3061; Australia
[phone] fax [phone]

e-mail [e-mail]

FW Murphy

P.O. Box 470248
Tulsa, Oklahoma 74147 USA
[phone]

fax [phone]
e-mail [e-mail]

www.fwmurphy.com

R

E

G

I

S

T

E

R

E

D

USA–ISO 9001:2000 FM 28221

UK–ISO 9001:2000 FM 29422

Printed in U.S.A. 0777070

E

Float arm is
adjustable but
cannot be
removed.

D

1/2 NPT

A

BC

1/2 NPT

Float is removable
and replaceable

3 in.

(76 mm)

L971-AModel

TOP

L971 and L971-B L971-C

TOP

TOP

Case/Float

Configuration

(front view,

less cover

and gasket)

Model

L971-D and L971-E L971-F L971-G

TOP

TOP

TOP

Case/Float

Configuration

21°

21°

(front view,

less cover

and gasket)

NOTE: Switches shown tripped on falling level.