11
Customer Enclosure Requirements (con’t)
Pressure Compensation
CAUTION
When an air conditioner is used on a sealed, pressurized enclosure the temperature inside the enclosure may
change rapidly when the air conditioner starts and when the compressor cycles. These conditions may cause the
enclosure pressure to decrease for a period of time below the required pressure. This can trip safety systems
associated with the purge/pressurization control equipment.
It is recommended that the control equipment be
selected and sized to compensate for this potential condition
. It is the user’s responsibility to make careful
adjustment to the pressure interlocks and flow adjustments to the purge system.
Should the purge/pressurization control equipment fail to compensate for the drop in pressure, a recommended safety
measure is to provide an additional amount of pressurized air to the enclosure independent of the purge/pressurization
control equipment (see drawing on page 12).
The Kooltronic air conditioner is equipped with an external terminal block marked “Pressure Compensation,” which is
connected to a relay inside the air conditioner. When the air conditioner compressor starts, the relay’s contacts are
closed.
Users of the air conditioner can utilize these contacts with their controls to add additional pressurized air to the
enclosure. The contact closure may be used with their control system having a timer function and output signal. The
output signal would energize a solenoid valve equipped with a fixed orifice or an adjustable needle valve within the
enclosure. This would provide additional pressurized air for a selected period of time (typically two to three minutes).
The relief valve utilized on the purge/pressurization control equipment must be capable of handling the capacity of
the solenoid valve in a failure mode. The timer function allows pressurized air to be added during the time the
temperature is ramping down within the enclosure, maintaining the proper pressure. Once temperature stability is
achieved and the air conditioner is running constantly, the internal pressure will be controlled by the
purge/pressurization control equipment. Subsequently, the solenoid valve is energized on each compressor start. The
installation should be tested to determine enclosure pressures, safety interlock settings, system operation and the
time interval that the solenoid air valve is open.
DISCLAIMER
This information is provided as a general guide, and is not intended to be instructional. Kooltronic makes no claims,
promises or guarantees about the accuracy, completeness or adequacy of this information. Any action taken based
upon this information is strictly at your own risk.
Kooltronic accepts no liability for the content of this information, or for the consequences of any actions taken on the
basis of the information provided.
