World Leaders in Ultra-Pure Heating
Revision 10
www.heateflex.com
01/17/13
405 E. Santa Clara St.
Arcadia, CA 91006-7218
Tel: (626) 599-8566 Fax: (626) 599-9567
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4.3.2 Process Over-Pressure
The unit is fitted with PVDF pressure-relief valves located on each of the output manifolds on
the top of the heat exchanger, which are set to approximately 60 psig. If for any reason the
tube side pressure rises above that pressure, the valve will vent and relieve the excess pressure
and then reset. See Section 8.4 Pressure Relief Valve Calibration Procedure for the
recommended calibration procedure.
This venting will also trigger a liquid level float fitted in the exhaust line of the pressure relief
valve, which will act as an input to the Auto-Shutdown System, which will close a pneumatic
ball valve on the steam supply at the inlet to the exchanger.
Please note that a small venting is normal subsequent to the activation of the Auto-Isolation
System. When the D.I. water isolation valves upstream and downstream of the unit close there
can be continued heating of the water in the exchanger tubing and the associated thermal
expansion. The pressure relief valves will vent momentarily to prevent a build-up of pressure
due to this thermal expansion.
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4.3.3. Low Process Pressure
Low process pressure protection is provided by a pressure gauge/transducer, which senses the
incoming D.I. pressure. This pressure gauge provides a visual method of display and in
addition sends the pressure reading to the PLC which acts as in input to the Auto-Shutdown
System and Auto-Isolation System. The Low Process Pressure alarm set point and alarm delay
can be modified on the Diagnostic Information screen of the Low Process Pressure Alarm.
The default Low Process Pressure Alarm and Low Process Pressure Delay set points are 15 psi
and 20 seconds respectively.
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4.3.4. Low Process Temperature
The Low Process Temperature alarm has no effect on the operation of the unit and serves to
notify the operator of the condition only. The Low Process Temperature alarm set point and
alarm delay can be modified on the Diagnostic Information screen of the Low Process
Temperature Alarm. The default Low Process Temperature Alarm and Low Process
Temperature Alarm Delay set points are 20
o
C and 20 seconds respectively.
