Clean Door Gasket; Vacuum Relief Port - Thermo Scientific 5900 Series User Manual

Section 4 Section 4
Maintenance Maintenance

Clean Door Gasket

Vacuum Relief Port

4-4 Model 900 and 5900 Series
The door gasket should be cleaned monthly, at minimum. Using a soft
cloth, remove any frost build-up from the gasket and door(s). The door
gasket may need to be cleaned more frequently if dirt or excessive frost build-
up prevents the door from closing properly.
The exterior door gasket provides an excellent seal to protect product,
provide an energy efficient thermal barrier to keep cold air in and room
temperature air out, and reduce frost build up on the inner doors.
Because the door gasket seals so well, a vacuum can be created after a door
opening. Warm air enters the cabinet, cools and contracts, creating a vacuum
that pulls the door in tightly against the seal.
To equalize the pressure inside the cabinet after a door opening requires 1.5-
3.0 cu.ft. of ambient air to be drawn into the cabinet. The amount of air
required to equalize the pressure varies depending on the cabinet size, cabinet
temperature, duration of door opening, inventory volume and the
temperature/humidity of the ambient air. The unit is designed with a
"vacuum relief port" that allows the pressure to be equalized.
The time required to draw 1.5-3.0 cu.ft. of air into the cabinet depends on
two factors:
a) size and number of paths available for air to enter the cabinet, and
b) pressure difference between 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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