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BLSK1 Series

Operates Bilge Pumps or Alarms

Uses Proven “Air Cell” Actuated System

Remote Switch and Moving Parts Kept
Unaffected by Corrosion

Aluminum Body and Cover

Includes 3 Assemblies: 

(1)

BLS1 Bilge Level Switch

(2)

MACT1 Tube Kit (Sensor Line and Fittings)

(3)

MAC1 “Air Cell” (Volume Cell)

Description

The BLSK1 Bilge Level Switch System 

gives

you all items and fittings necessary to install in
your bilge. Or, you can have only the parts you
want and you provide brackets, tubing and mount-
ing hardware.
Using the proven “Air Cell” actuating system, all
moving parts and switching are remote from bilge
liquids and are thus not affected by corrosion,
rust, etc. All wetted parts are of non-corrosive
materials.
As bilge level rises a column of air is captured in
the 

MAC1

Air Volume Cell. The rising bilge

level compresses the column of air creating pres-
sure against the large diaphragm in the 

BLS1

Bilge Level Switch and the switch trips. Switch
set point is adjustable.
The switch resets as the bilge is pumped out.  Air
cell recharges itself during normal operation.

The BLS1 

is constructed of materials not affected

by marine atmospheres; Aluminum or Bronze
body and cover, Buna-N diaphragm.

Specifications

BLS1 Bilge Level Switch

Snap-Switch SPDT (standard)

• 5 A @ 125, 250, or 480 VAC  
• 1/2 A @ 125 VDC, 1/4 A @ 250 VDC

NOTE:

A pilot relay may be used for higher

contact ratings (see Typical Wiring Diagram).

Case/Lid:

Aluminum (std).

Bottom Plate:

Glass-filled Nylon.

Process Connection:

1/4 NPTF.

Max. Pressure:

25 

psi

(172 

kPa

) [1.72 

bar

].

Conduit Connection (electrical):

1/2 NPT.

BLS1 Weight:

3 lb. (1.4 kg). 

BLS1 Dimensions:

6-1/4 x 6-1/4 x 6-1/4 in.

(159 x 159 x 159 mm).

15050737 Optional mounting bracket

16 ga., 304 stainless steel (see Dimensions).

MACT1 Tube Kit (fittings included)

4 ft. (1.21 m) flexible non-corrosive 
tubing, 1/4 in. (6 mm) dia. (cut to fit).

MACT1 Weight:

0.5 lb. (0.23 kg).

MACT1 Dimensions:

6 x 6 x 6 in. (152 x 152

x 152 mm).

MAC1 Air Cell (Volume Cell)

• 

Made of non-corrosive materials

• 

(2) 1/4-20 stainless steel hex bolts and nuts.

MAC1 Weight:

2 lb. (1 kg).

MAC1 Dimensions:

6 x 6 x 6 in. (152 x 152 

x 152 mm).

Dimensions

(1)

(2)

(3)

MACT1 Tube Kit
(Sensor Line)

BLS1 
(Bilge 
Level
Switch)

MAC1
(Volume Cell)

Optional Mounting Bracket (15050737)

1/2 NPT for electrical
connections

6-5/32 in.

(156 mm)

5-1/2 in.

(140 mm)

4 feet long

(1.21 m) std.

1/4-20 hex bolt
(2-places) and nuts

9/32 in. (7 mm) dia.
4-places

3-1/4 in.

(83 mm)

5-3/16 in.

(132 mm)

2-3/8 in.

(60 mm)

1-1/2 in.

(38 mm)

BLSK-95107B

Revised 10-03

Catalog Section 15

(00-02-0052)

Bilge Level Switch System

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