Appendix
Thermo Scientific XBF40-MD Series Blast Freezers
Installation, Operation and Service Manual
37
THE VACUUM PUMP
When evacuating a system, there is an initial flow of gases and moisture
toward the vacuum pump but, as the vacuum becomes deeper, it is
recommended to perform a triple evacuation to ensure that as much as
possible moisture is removed. For this reason, a means of speeding up the
evacuation process called triple evacuation is required. (See EVACUATION
PROCEDURE).
Always start the vacuum pump procedure with new clean oil and should
change it during after the first deep evacuation (while the oil is still hot) and
after each evacuation job because it becomes contaminated during the
process of evacuation. If the pump oil is contaminated, it will be apparent
that the pump’s capability to achieve a good deep vacuum will be
compromised. Also, remember that moisture in the pump oil is a mortal
enemy of the finely machined surfaces inside the pump and which will affect
the life and performance of the pump. It is good practice to change the
pump oil after each use, using the dry oil recommended by the pump
manufacturer. The pump should be put away in a clean, dry condition ready
for the next job.
