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Vission 20/20 • Operation and Service Manual •Vilter/Emerson • 35391SC 1.8.5153
Section 25 • Cool Compression Control
Overview
The cool compression compressor operation is similar
to the standard single screw compressor units, except
there is no external oil cooler to the unit. A blanket of
liquid ammonia lies on top of the oil in the oil separa-
tor. The liquid ammonia level is regulated by sensing
the liquid ammonia level with a level probe, and using
a positioning valve to vary the amount of liquid ammo-
nia being added to the separator. The cooling occurs
through the entire compression and separation process.
The Cool Compression compressor does not have an oil
pump. When the Cool Compression compressor unit is
commanded to start, the control panel fi rst insures that
the slide valves are at their minimum positions. The suc-
tion oil injection solenoid (SOI) is energized – allowing a
path for oil to fl ow into the compressor. The compressor
now starts. There is an initial pressure drop in the suc-
tion chamber of the compressor and a corresponding
increase in pressure on the discharge of the compres-
sor. This creates a pressure differential that forces the
oil and liquid ammonia mixture through the suction oil
injection line into the suction chamber of the compres-
sor. This oil and liquid provides lubrication and cooling
until full pressure differential lubrication is attained. As
the differential pressure increases, the oil and liquid am-
monia is now injected into the screw during the com-
pression process and the oil injection valve is allowed to
close.
Setup
Confi guration Screen:
• To setup the Vission 20/20 panel for Cool
Compression, fi rst ensure that an analog output card
is installed in the panel, and it is selected/enabled
from page 6 of the confi guration screen, see Figure
25-1. Cool Compression Control Screen. Navigate to
confi guration page 2, and select “R717-Cool Comp”
from the drop-down box that is labeled “Refrigerant”.
Once selected “Cool Compression” option will ap-
pear in Oil Pump and Oil Cooling sections and “Cool
Compression” gets selected automatically. It will also
Figure 25-1. Cool Compression Control Screen