ClimaCool IOM AR2 SERIES - Manual (Page 52)

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Refrigerant Charging
Once leak testing and evacuation are complete, refrigerant charging
may commence . Always refer to the unit nameplate and the guidelines
within this section in order to establish the quantity of refrigerant
required . IMPORTANT: Always introduce refrigerant into a system
using a charging manifold with gauges, along with a refrigerant scale
to accurately weigh the refrigerant cylinder throughout the entire
charging process . As noted in an earlier section, the end user and
installing contractor must determine whether refrigerant R-22 or
R-407C is to be used . It should be clearly understood that R-407C is a
“tertiary blended refrigerant”, which experiences a temperature glide
(near 11°F rise) when traversing from saturated liquid to saturated
vapor at constant pressure throughout an evaporation process .
Because it is a “glide” refrigerant, vapor drawn off the top of a bulk
R-407C cylinder will not have exact fractional constituents versus the
mean bulk liquid in the cylinder . For this reason, we recommend ALL
REFRIGERANT CHARGING to be drawn as liquid fractions from
the bottom of the charging cylinder . When initially charging a system
that is in a vacuum, liquid refrigerant can be weighed directly into the
high side while the compressor is off .
CAUTION: Never dispense refrigerant amounts into the receiver
which may exceed its liquid holding capacity. Both refrigeration
systems in models AR2-25 and AR2-30 are equipped with
72 pound receivers (at 80% full). Both refrigeration systems
in models AR2- 50 and AR2-65 are equipped with 84 pound
receivers (at 80% full).
As much refrigerant as possible should be charged in this manner
until the receiver holding capacity is achieved, or system pressures
equalize preventing additional refrigerant from being added . Even
if system equalization occurs, it is still possible to inject liquid
refrigerant into the system by placing the refrigerant cylinder into a
luke warm water bath NO WARMER THAN 110°F!
SAFETY/ALERT: Cylinder pressures must be closely monitored
whenever a refrigerant cylinder is being heated in ANY manner.
Allowing pressures to exceed those for which the cylinder is rated,
may result in cylinder rupturing, personal injury and/or property
damage or even death.
Once system and refrigerant cylinder tank pressures have equalized,
it will be necessary to finish the refrigerant charging process by
gradually metering small bursts of liquid refrigerant into the suction
line of the compressor while it is operating .
SAFETY/ALERT: Never attempt to vapor charge into the system
high side, whether the compressor is ON or OFF. This may
result in refrigerant flowing from the refrigeration system into
the charging cylinder. Cylinders can quickly be over pressurized
causing them to rupture with resultant injury and property
damage.
IMPORTANT: Never dispense liquid refrigerant into the
suction port of a compressor while it is not running. If adding
additional refrigerant is necessary, you must gradually meter
liquid refrigerant into the suction port of the compressor ONLY
WHILE THE COMPRESSOR IS RUNNING, and only through
a metering valve.
The only exception to the above recommendations to meter in
liquid refrigerant into the suction line is the following: Providing the
ENTIRE contents of the refrigerant cylinder is intended to be added
to a refrigeration system, it is perfectly acceptable to vapor charge
form this cylinder into the compressor suction line until all refrigerant
is injected .
While on the subject of “Fractionation” with refrigerant R- 407C
(whereby the original weight fractions of the three refrigerant
constituents is suspiciously altered following a noticeable refrigerant
leak), it should be further understood that any refrigerant leak
originating from a saturation, 2- phase area of the system is cause
for concern . If enough refrigerant has escaped to effect normal
refrigeration, the safest procedure is to reclaim the remaining
refrigerant from the system, repair the leak, reprocess the system and
weigh in a new liquid refrigerant charge . “Fractionation” is negligible
in areas of the system where the refrigerant is predominantly liquid or
predominantly vapor . However, systems having repetitive leaks may
require complete evacuation and recharge .
The amount of refrigerant required in a system depends on the
following:
• model size of the equipment,
• the distance of the interconnecting lines between the AR2 module
and the condenser section;
• the specific head pressure control methods used for low ambient
operation;
• what (if any) fan cycling controls are supplied with the
condenser, and;
• whether optional compressor unloading is possible using hot gas
bypass/combination liquid injection .
Refer to the tables to determine the amount of additional refrigerant
required when using flooding type head pressure controls . They are
for use with standard units and should not be used with oversized
condensers . All systems use two refrigeration circuits . The additional
charge shown is per circuit .
Refrigerant Charging Procedure