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TM 5-4210-220-12
Table 4-2 UNIT TROUBLESHOOTING - Continued
MALFUNCTI ON
TEST OR INSPECTION
CORRECTIVE ACTION
5h
FOAM ENTERING WATER TANK
Step 1
Check air connection, hoses, shuttle valve on water tank valve.
Tighten/remake joints or replace hose or shuttle valve.
Step 2
Operate tank valve manually.
If valve operates full 1/4 turn, seal is faulty. Replace valve.
5j
WATER ENTERING FOAM TANK
Step 1
Check air connection, hoses, shuttle valve on foam tank valve.
Tighten/remake joints or replace hose or shuttle valve.
Step 2
Check whether valve in foam line has failed.
Replace foam check valve, (see para. 4-18).
Step 3
Foam tank valve has failed.
Replace foam tank valve or actuator, (see para. 4-18).
5k
FOAM PERCENTAGE DOES NOT MEET SPECIFICATION
Step 1
Check correct water flow used for calculation.
Repeat test with meter valve set according to new flow rate.
Step 2
Check foam metering valve for cleanliness and correct operation.
Replace metering valve, (see para. 4-18).
Step 3
Foam tank valve not opening fully.
Replace foam tank valve or actuator, (see para. 4-18).
Step 4
Foam check valve has restriction.
Replace foam tank check valve, (see para. 4-18).
Step 5
Check venturi for cleanliness.
Remove and clean venturi, (see para. 4-18).
Step 6
Check foam concentrate for contamination.
Drain tank and fill with proper solution.
4-31
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