Refrigerating Specialties Division
8
SERVICE POINTERS (Check General Procedure)
SYMPTOM
PROBABLE REASON
CORRECTION
Regulator does not
Diaphragm or seat dirty, damaged or frozen.
Clean or replace. Clean strainer.
shut off flow.
Diaphragm follower stuck or damged.
Clean or replace. Install follower carefully.
Piston jammed with excess dirt.
Remove and polish piston and bore with crocus cloth. Clean valve and
strainer.
Throttling plug leaking due to excess
Clean or replace. If used on liquid, check for
dirt or damage.
erosion due to excessive flash gas. Reduce flash gas by subcooling or by
reducing pressure drop across valve by providing restriction at valve outlet.
Diaphragm ruptured or badly deformed.
Replace. If Range “D” make sure has 2 diaphragms.
A4AB Modular Solenoid Pilot seat leaking.
Check seat and needle. Replace as needed,
A4AS Modular Solenoid Pilot seat leaking.
Check seat and needle. Replace as needed.
Diaphragm and seat eroded due to flash gas.
Replace. Reduce flash gas by subcooling or by reducing pressure drop
across regulator by providing restriction at valve outlet.
Modular Solenoid Pilot not closing.
Check power at leads, make sure coil is de-energized.
Regulator does not
A4A (inlet) Pressure Regulator Diaphragm
Replace. It Range D make sure has 2
open
ruptured or badly deformed.
diaphragms.
Diaphragm follower stuck, damaged or frozen.
Clean or replace. Install follower carefully.
A4AS/A4AB Modular Solenoid
Pressure drop across valve too high; over 21 bar (300 psig). Lower pressure
Pilot not opening.
drop. Improper power supply. Correct. Replace solenoid coil.
Piston worn, too much clearance.
Replace piston. Check for reason. If used on liquid, check for flash gas.
Regulator Operation
Diaphragm or seat dirty or damaged.
Clean or replace. Clean strainer.
erratic.
Diaphragm follower has dirt on the outside
Clean or replace.
diameter or outside diameter is damaged.
Other system components, line controllers,
Adjust, repair or replace.
thermostats, etc., erratic.
Regulator too far oversized.
Check load. Replace with smaller regulator or investigate use of reduced
capacity plug.
Pressure drop across
Inlet or outlet restricted.
Check for restriction. Clean strainer.
regulator too high.
Regulator too small.
Open manually to be sure valve is full open.
Replace with proper size regulator.
Large amount of flash gas in liquid line.
Reduce flash gas by subcooling. Reduce line restriction by increasing line
size, particularly at the regulator outlet. Replace with larger regulator.
High pressure drop causes high rate of
Increase pipe size at the outlet of the
expansion of gas at regulator outlet.
regulator.
Regulator does not open all the way.
Check piston for wear. Replace, it needed.
