Vilter VSM 71-701, Operation And Service Manual

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25
Installation
allow the pump to operate 2 or 3 hours. Stop the
pump and let the system stand with this vacuum.
Again using dry nitrogen, raise the system pres-
sure to zero.
For the third evacuation, follow the previous pro-
cedure with the pump operating until system pres-
sure is reduced below the 1000 micron level. Run
the pump an additional 6 hours and hold the sys-
tem for approximately 12 hours at low pressure.
After this, again break the vacuum with dry ni-
trogen and allow the pressure in the system to
rise slightly above zero pounds (psig). Install new
drier cartridges and moisture indicators. Charge
the system once more below the 1000 micron level
and use the refrigerant designed for the system.
When properly evacuating the system as outlined
above, the system is dry, oxygen-free and free of
non-condensables. The piping should not be in-
sulated before the evacuation process is started.
If moisture is in the system before evacuating, it
condenses in low places and freezes. If this hap-
pens, it can be removed by gently heating the trap
farthest away from the vacuum pump. This causes
the ice to melt and water to boil. Water vapor
collects in the next trap towards the vacuum pump.
This process should be repeated until all pockets
of water have been boiled off, and the vacuum
pump has had a chance to remove all the water
vapor from the system.
VII. UNIT OIL CHARGING
The compressor unit is shipped from Vilter with
no oil charge. The initial oil charge can be made
through the drain valve at the oil receiver/separa-
tor. Vilter motor driven and manually operated
oil chargers are available for this purpose. Once
the unit has been started and is operating above
50% capacity, oil may have to be added to bring
the oil level to the normal operating point. With
the unit operating, oil should be added through
the charging connection at the suction strainer.
The normal operating level is between the (2) sight
glasses on the oil separator. See Table 2 for ap-
proximate oil charge requirements.
TABLE 2. OIL CHARGE
Oil Separator Size Approximate Oil
Charge – Gallons
VSR 16” 20 to 27
VSR 20” 22 to 31
VSM 20” 20 to 25
VSM 30” 30 to 35
20” 30 to 40
24” 40 to 50
30” 60 to 75
36” 95 to 105
42” 145 to 165
The oil level may be above the top sight glass at
this time. Later, when the unit is placed in op-
eration, there will be some drop in the oil level
as the various oil lines, oil filter and other pip-
ing becomes charged with the normal amount of
oil that will be in circulation. This drop in oil
level should bring the level in the oil receiver/
separator into the normal operating range. Do
not mix oils.
A. Oil For Single Screw Compressors
Due to the need for adequate lubrication, Vilter
recommends only the use of Vilter lubricants,
designed specifically for Vilter compressors.
With the extensive research that has been per-
formed, we are able to offer refrigerant specific
lubricating oils. Use of oil not specified or sup-
plied by Vilter will void the compressor warranty.
Please contact your local Vilter representative or
the Home Office for further information.
VIII. SYSTEM REFRIGERANT
CHARGING
CAUTION
When charging the system, make sure the com-
pressor unit is pressurized from the discharge
side of the compressor. Pressurizing the com-
pressor from the suction side may cause rota-
tion of the compressor, without oil supply, which
could lead to internal damage.