Evoqua Wallace&Tiernan 50-200 Series, Manual

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WT.050.200.001.UA.IM.0814
50-200 EVAPORATOR FOR CHLORINE
40
EVOQUA W3T98237
The pump is the end-suction type. If the evaporator is to be shut down for an
extended period of time, remove the plug at the bottom of the pump impeller
housing to fully drain the pump.
CAUTION: Failure to fully drain the pump could lead over time to corrosion
build-up and permanently damage the pump.
Replace plug after draining.
4.10 Evaporator Pressure Relief System
A pressure relief system conforming to ASME Boiler and Pressure Vessel Code
recommendations is supplied with the evaporator. This pressure relief system
consists of a rupture disc (rupture point 400 psi), a pressure switch (set at
20 psi), and a pressure relief valve (set at 560 psi). The evaporator will not,
under normal operating conditions, reach these pressures, but in abnormal
circumstances, such as a closed inlet and outlet valve, these pressures could
develop. The alarm actuates when the disc ruptures or develops a leak. This
alarm serves as a signal that conditions exist that can cause gas to be relieved
out of the system. A Pressure Relief System Alarm indicates that the evaporator
system requires immediate corrective attention.
WARNING: TO AVOID SEVERE PERSONAL INJURY, BE FAMILIAR WITH
EMERGENCY PROCEDURES, TROUBLESHOOTING PROCEDURES, AND
SERVICE SO THAT PROMPT AND EFFECTIVE ACTION CAN BE TAKEN.
Overpressure in the evaporator cylinder can result from a closed outlet valve
or stopping of the chlorinator in conjunction with a blockage in the liquid inlet
line, a closed valve in the liquid inlet line, or excessive “air padding” of tank
cars. If the pressure relief system alarm actuates, the cause must immediately
be determined and corrected. Refer to the Troubleshooting Guide, Symptom,
Group 2, in this section. If an alarm is actuated, observe the evaporator pres-
sure gauge. If it reads normal (30 to 140 psi), the rupture disc may be faulty.
To resume operation after correction of the overpressure problem, replace
the rupture disc. Purge any gas from the pressure relief system piping lines
with dry air, nitrogen, or carbon dioxide as soon as possible after system
actuation. Check the relief valve for leaks using 150 psi pressure. The valve
must be leak-tight to function properly.
WARNING: TO PREVENT MAJOR RELEASE OF CHLORINE, CAUSING POS-
SIBLE SEVERE PERSONAL INJURY, DO NOT REMOVE THE PRESSURE RELIEF
SYSTEM WHILE THE EVAPORATOR IS PRESSURIZED.
Before attempting to service the relief system, follow step a in paragraph 4.12,
“In-Place” Cleaning Of Evaporator Cylinder. If, after this step, the pressure switch
remains actuated, chlorine under pressure is still present in the pressure relief
system. This indicates a leaking (not ruptured) rupture disc.
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