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Section 2.3: Troubleshooting Failure Modes
If V1 failed with cold port closed (hot port open):
hot water from outlet of HtEx flows to V5 premix
valve where hot inlet to V1 is combined with cold water to about 105F. This triggers V4 to close V3 so
no steam flows to HtEx and only cold water flows to shower/eyewash.
If V1 failed with hot port closed (cold port open):
cold water into V1 flows to shower/eyewash.
Section 2.3.1: V1 Failure Mode
If V2 fails open:
loss of steam flow control to HtEx. Full steam flow at all water temps. If V1 is
functional, it will proportion hot and cold-water flow to maintain 80°F output to system. If V4 is func
-
tional, it will turn off V3 if output from V1 is too high. (Excess steam will escape through drain line.)
If V2 fails closed:
no steam flow to HtEx; unit flows only cold water to system. Water outlet tee is
cold to the touch. Debris may be causing the steam valve to stay closed. At low flow the outlet tem
-
perature will be about 80°F, at high flow the outlet temperature is below the required temperature.
Section 2.3.2: V2 Failure Mode
If V3 failed closed:
no steam flow to HtEx; unit will output cold water; V3 indicator will not move.
If V3 fails open:
steam flow to HtEx is always on. V2 controls temp of hot water out of HtEx. V1
mixes hot and cold water to control 80°F output; assume V4 cannot close V3, so V4 has no effect.
Steam will leak from the drain line even when the shower/eyewash unit is not activated. Large water
leaks (over 1 GPM) down stream would produce lower water pressure on the lower diaphragm
housing, possibly opening V3. Debris may be stuck in sealing area or V3 may be jammed open.
Section 2.3.3: V3 Failure Mode
If V4 failed closed:
no significance unless V1 also fails. Output temperature is over 95°F for more
than 15 sec.
If V4 failed open:
steam will not turn on, so only cold water flows from the Heater. V3 may open
during the shower operation and allow steam to pass, but V3 will not open during eyewash operation.
Debris may be stuck to the seat area inside the V4 not allowing a good seal.
Section 2.3.4: V4 Failure Mode
Hot port closed:
only cold water would be supplied to V1 and unit will output cold water.
Cold side port blocked:
hot side will shut itself off, not supplying V1 at all and would produce
supply water temperature. Cold side port is not regulated so only a blockage can cause cold side port
to close water flow
Section 2.3.5: V5 Failure Mode
Valve failed closed:
outlet water temperature “spike” to slightly over 100F for a couple of seconds.
Valve failed open:
increased water discharge into drain connection.
Section 2.3.6: V6 Failure Mode
Note: Prior to starting any troubleshooting, look to see what is visible before activating water flow.
(Any leaks? Excess water or steam vapors from drain line? Any visible damage?)
Summary of Contents for THERM-O-MIX STATION
Page 13: ...Page 12 Appendix 1 Station Schematic...
Page 14: ...Appendix 2 Station Operating Logic Flow Chart Page 13...
Page 15: ...Page 14 Appendix 3 Typical Installation Schematic...
Page 16: ...Appendix 4 Labeled Station Line Drawing Page 15...
Page 17: ...Page 16 Appendix 5 Hoses and Hose Fittings Line Drawing...
