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4.3
TEMPERATURE CONTROL
An external control system is required for operating the IDH; see Figure 4-2 for a
typical control set up. The system should consist of:
temperature control system, interlock controls (see Section 2.3), and
outlet liquid temperature sensor(s).
Operating settings and parameters are to be determined by the user.
The control scheme should be set up to not only control the liquid outlet
temperature but also limit the heater element surface temperature to a maximum
of 250° C (see Section 2.3.b).
The control system should supply a pulse width with a period less than 1 second
to prevent element damage.
The main Circuit breaker must be in close proximity to the equipment and within
easy reach of the operator. It also must be marked as the disconnecting device
for the heater. The circuit breaker should be sized according to the breaker
manufacturer's specification (generally this is max current draw +25%) and the
heater size shown in Sec. 3.1.
4.4
SHUT DOWN
The following procedure should be used to safely shut down the heater:
•
Cut-off power to the heater.
•
Allow liquid to pass through the heater for at least 5 minutes or until the outlet
temperature drops below 50°C.
MODEL IDH OPERATION / MAINTENANCE MANUAL
Figure 4-2
PAGE 11
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