Pentair MYERS MSP50A, Owner'S Manual

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11. Manual pumps. All general 

instructions for automatic 

pumps apply to manual pumps 

except the level switch is not 

used and the power cord does 

not have a vent tube.

  Manual models have the plug 

(12) in switch cap for installing 

a fitting to air test the pump 

for leaks. Replace all plugs 

with Permatex on threads. The 

switch housing seat is tapped 

and plugged with pipe plug.

MYERS  pumps have a small air 

vent hole in the impeller cavity 

to let out trapped air. If this hole 

becomes plugged, pump may air 

lock. To break the air lock, use a 

small screwdriver to clear hole in 

the impeller cavity.

As a secondary precaution in 

installations of this type, 1 ⁄ 16” 

hole should be drilled in the   

discharge pipe below the check 

valve. The check valve should 

be 12 to 18 inches above pump 

discharge. Do not put check valve 

directly into pump discharge 

opening.

NOTE:  In sumps where the 

pump is operating daily, air  

locking rarely occurs.

  Pump is now ready for check 

run before air testing and 

filling with oil. Plug cord 

(21) into power receptacle and 

push up on switch chamber 

diaphragm (23) to start motor. 

Motor should start and run 

smoothly. When pressure is 

released on diaphragm, motor 

should stop. Repeat operation 

2 to 3 times to be sure 

operation is satisfactory and 

not binding.

9.  Air test. To air test unit, put 

air fitting in plug opening (12) 

and charge motor housing with 

air to 7 psi. Do not use higher 

pressure or seal will be blown 

open. Charge switch cap with 

air through nylon vent tube 

as described earlier and place   

complete unit under water.

  No air bubbles should show 

on this test. If leak shows,  

unit must be dismantled to  

correct leak.

10. Oil fill.  After  air  test  is           

satisfactory, remove from 

water and wipe or blow off 

any excess water.

  Do not put oil in motor with 

any water present that could 

get into motor.

  Fill to 1 ⁄ 8”  over  motor  plate 

through opening. Use oil fill 

tube that will go into holes so 

that air can escape. Replace 

plug (12) and pump is ready 

for operation. Use only high 

grade transformer oil or special 

Myers submersible oil in 

motor.

Pump

Servicing

Performance Curve