TechNet-21 - Forum

This forum provides a place for members to ask questions, share experiences, coordinate activities, and discuss recent developments in immunization.
  1. Larry Schlussler
  2. Cold chain equipment
  3. Tuesday, 19 October 2010

Compressor Replacement Without a Vacuum Pump

Replacement of a compressor requires the use of a vacuum pump. Solar
powered vaccine refrigerators are generally located away from the
utility grid. Most vacuum pumps are powered by AC grid power making
compressor replacement difficult. We have developed a method of
removing the air from a system without the use of a vacuum pump. The
method requires the installation of an access valve on the high and
low side of the system.

Evacuation Procedure

1 - With the new compressor installed, turn on the compressor and
depress the access valve on the high side of the system. Monitor the
pressure on the low side of the system. When the pressure is as low
as it will go, close the access valve on the high side of the system
and turn off the compressor. This process will take about 5 minutes.
2 - Charge the low side of the system to approximately 14 psi.
3 - Wait about 3 minutes for the pressures on the high and low side
to equalize.
4 - Now turn the compressor on and depress the access valve on the
high side. When the pressure on the low side is as low as it will go,
let the high side access valve close and turn off the compressor.
5 - Repeat steps 2, 3 and 4. Note, on successive evacuations, the low
side pressure will not go as low because of the absorption of
refrigerant in the compressor oil and it’s slow release.
6 - Charge the low side of the system to approximately 14 psi.
7 - Wait 3 minutes for the pressure to equalize. Turn on the
compressor and depress the access valve on the high side. This time,
when gas is no longer coming out the high side access valve, let the
valve close. The air is now purged from the system.
8 - Charge the system with the appropriate amount of refrigerant and
turn on the compressor.
9 - Make appropriate adjustments in system charge if necessary.
##text##

Alejo Bejemino Accepted Answer
In refrigeration practice we call it self-vacuum. Self-vacuum (vacuuming process using the refrigerant compressor) can be applied to all domestic type refrigeration systems repair including the solar powered vaccine refrigerators. Extra caution should be exercised in using self-vacuum as refrigeration system is sensitive to both moisture and dirt. Moisture and dirt trapped in the system could block the capillary tube thus resulting to intermittent cooling or no cooling at all. Refrigerant compressor replacement is a major repair of the refrigeration system. Every refrigerant compressor replacement work should be preceded by flushing the high side and low side of the refrigeration system. This will ensure that dirt or solid particles that are caught in the system are removed. Flushing the refrigeration system, replacement of filter drier and capillary tube is a must especially when refrigerant compressor replacement is required due to burn out refrigerant compressor motor windings.
  1. more than a month ago
  2. Cold chain equipment
  3. # 1
James Cheyne Accepted Answer
WHO issued training materials a few years ago describing how to evacuate a refrigeration system without having access to a vacuum pump. This training course "Refrigerator-repair technician’s course for compression refrigerators" is still listed in WHO's Vaccines and Biologicals Department 'Catalogue 2003'. A PDF version of which can be found on http://www.who.int/vaccines-documents/www690.pdf (http://www.who.int/vaccines-documents/www690.pdf). James
  1. more than a month ago
  2. Cold chain equipment
  3. # 2


There are no replies made for this post yet.
Be one of the first to reply to this post!