Tenney BTS - Page 15

TENNEY ENVIRONMENTAL
PURGE AIR SYSTEM (Optional)
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USING COMPRESSED AIR or NITROGEN
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As an option, your chamber may be equipped with a dry air or GN, purge system which is
activated by an event output from the Watlow
942 Controller. To use the system, the event
must be
turned on as explained in the Watlow 942 manual. Event No. 2 is generally used for
this function. However, a reference table defining the function of each event is affixed to the
control panel of each chamber. Please check this table before operating the chamber.
A metering valve and flowmeter is supplied as part of the system to establish the design purge
flow. The valve should
be adjusted until the indicated flow is about 300 cubic feet per hour.
The
GN, purge system is primarily utilized to provide an inert atmosphere which minimizes the
buildup of moisture and prevents condensation on the product under test. Eliminating the
oxygen in the chamber air helps prevent corrosion of the product under test.
A drier is provided for compressed air purge systems. This system requires
a supply of
relatively oil free compressed air at a minimum pressure of 80 PSIG. This air is dried by a twin
tower heatless, self regenerating dryer and is introduced into the chamber through
a solenoid
valve.
As an option, your chamber may be provided with either a circular or strip type chart recorder
' )
to record temperature versus time. This recorder is typically a one pen type which also digitally
displays the process value.
A 100 ohm platinum RTD is used for temperature measurement
and is normally placed in the plenum of the chamber.
The recorder configuration is documented in the Test Report, which is located in the
Supplemental Instructions Section. For complete details on the operation of the recorder,
please reference the recorder's user's manual which is located in the same section.
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