Evoqua Wallace&Tiernan 50-200 Series, Manual

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50-200 EVAPORATOR FOR CHLORINE
WT.050.200.001.UA.IM.0814
29
EVOQUA W3T98237
passing through the evaporator outlet, resulting in a hazardous condition of
operation. Therefore, a periodic record of superheat will permit the opera-
tor to schedule the cleaning of the evaporator well in advance. As noted
previously, the evaporator is functioning properly as long as there is some
superheat. Due to tolerance in gauges, the first cleaning of a new evapora-
tor should be scheduled when the superheat has dropped to about 10°F.
Examination of the interior of the cylinder when the head (upper flange)
is removed for cleaning can guide the operator in judging what value of
superheat should be used as a criterion for further cleanings.
NOTE: The specific pressure/temperature values used in this example were
obtained from the Chlorine Manual, published by the Chlorine Institute, Inc.
3.2.3 Shutdown
• Short-Term Shutdown.
a. Close the evaporator outlet valve. When the outlet valve is closed, gas
will form inside the cylinder, pushing liquid back to the supply container.
b. If the supply container does not have adequate reserve capacity to ac-
cept the maximum contents being forced from the evaporator cylinder,
do not stop chlorination.
WARNING: TO AVOID RUPTURE OF THE SUPPLY CONTAINER, CAUSING
POSSIBLE SEVERE PERSONAL INJURY, CLOSE THE SUPPLY VALVE AND
USE THE CHLORINATOR OR GAS DISPOSAL SYSTEM TO COMPLETELY
EVACUATE THE EVAPORATOR CYLINDER AND ITS CONNECTING PIPE-
LINES.
NOTE: The warning above applies if a situation is created, for example, where
a new, capacity-filled supply is connected to the evaporator and the previous
supply is disconnected or closed. If a liquid supply valve is then closed, after
additional liquid is forced into the capacity-filled supply container, pres-
sures capable of rupturing the container will develop with a slight increase
in temperature.
c. If the supply container can accept the maximum contents without ex-
ceeding its rated capacity, the outlet valve can remain closed through-
out the short-term shutdown; however, do not shut any valves in the
chlorine supply piping. With the evaporator outlet closed or with chlo-
rination stopped, as long as the inlet valve to the evaporator and the
valves to the ton container or tank cars are open, the pressure within
the evaporator cylinder is limited to never exceeding the pressure in
the ton container or tank car.
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