Thermo Scientific Revco 8920 Operating Manual page 27

Section 4 Section 4
Maintenance Maintenance
Vacuum Relief Port
(continued)
4-4 Revco ExF
The time required to draw 1.5-3.0 cu.ft. of air into the cabinet depends on
two factors:
a) the size and number of paths available for the air to enter the cabinet,
and
b) the pressure difference between the internal cabinet and the ambient
room.
Cabinets with the vacuum relief port operating normally, (i.e. vacuum relief
port is not iced over) will require a minimum of 30 seconds up to a
maximim of 120 seconds for the cabinet to equalize. This is also a good
indication that the exterior door is well sealed.
The vacuum relief port requires routine maintenance. It will ice over unless
preventive measures are taken. If the vacuum relief port becomes iced over,
the freezer will take several hours to equalize pressure.
Warning Do not leave the freezer unattended while the door is unlatched.
The vacuum could release, resulting in a door opening and product loss.
Observe the inner side of port periodically for frost and ice build-up.
Remove any frost with a soft dry cloth. If the tube should become clogged
with ice, it must be cleaned. Make sure during cleaning that the vacuum
relief tube is completely free of ice to prevent rapid ice formation.
Factors that can affect the performance of the vacuum relief port include:
high ambient temperature, high humidity conditions and frequent door
openings. Maintenance should be performed weekly or as needed.
Warning Failure to maintain the vacuum relief port may result in excessive
ice build up inside the tube, clogging the port, and inability to open the
door. The vacuum relief port may need to be cleaned more often with
frequent door openings and high humidity environments.
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