Thermo Scientific 700 Series Operating And Maintenance Manual page 23

Section 4
Maintenance
Clean Vacuum Relief
Port (continued)
4-4 Model 700 Series
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.
To open the door if a vacuum lock occurs:
1. Unlatch the handle of the freezer (Figure 4-1).
2. On the HINGED side of freezer (Figure 4-2),
slide part number 402058 tool, or a non-
metallic flat object such as a ruler, tongue
depresser or plastic putty knife, carefully between
the door gasket and door until only the end of
the tool handle is showing (Figure 4-3). There
will be a noticeable sound of air exchange that
could last a few minutes.
3. As the air pressure equalizes, the door releases.
Caution Do not leave the freezer unattended while
the door is unlatched. The vacuum could release,
resulting in a door opening and the potential for
product loss. ▲
Figure 4-3. Detail
Figure 4-1. Unlatched
Figure 4-2. Insert Tool
Thermo Fisher Scientific