Sharp AF-S100RX, Service Manual

Page: 35 / 62

Section 5 Sealed System
5 -9
Recovery Unit
Refrigerant recovery equipment needs to be R-410A
compatible. To determine if your existing unit is
approved, check the Air-Conditioning and Refrigeration
at www.ul.com. Recovery units must be approved for
Class V refrigerants including R-407C, R-404A and R-507
and others per ARI 740-98. For best performance with
your R-410A recovery equipment, it should have the
following features:
1. Oversized condenser
2. Oversized fan
3. Crankcase pressure regulator (CPR) valve
4. High-pressure cutout switch rated for at least 510
psi.
Recovery equipment also is available with a subcooling
feature, which aids in recovering R-410A. Subcooling
keeps the recovery tank pressure lower by ensuring that
the refrigerant is fully condensed before putting it into
the recovery tank. This will increase the rate of recovery
and reduce the wear and tear on recovery equipment.
Subcooling also can be accomplished by submerging the
recovery tank in a bucket of ice.
Oversized condenser
Helps completely condense the refrigerant and to keep
the recovery tank temperatures down.
Fan
The larger the fan and the more aggressive the pitch of
the blades, the more air is moved over the condenser.
More air ow also keeps critical internal components
cool, increasing their service life.
Crankcase pressure regulator (CPR)
This device will regulate the pressures so the recovery
equipment is not overwhelmed with high pressures when
working with R-410A. Units that use a CPR valve do not
require the technician to throttle or regulate the ow of
refrigerant to the recovery unit to prevent damage to the
compressor.
Dedicated Equipment Needed
A standard manifold set, hoses, recovery equipment
and recovery tank cannot be used when recovering
R-410A. The pressures encountered when working with
R-410A are too high for your standard equipment.
Here are the items a technician will need to safely
work with R-410A.
Manifold set
The pressures encountered while working with R-410A
require a manifold gauge set that has a low-side gauge
that reads up to 500 psig and a high side gauge that
reads up to 800 psig. This is higher than your standard
manifold set.
Use a micron gauge to pull a vacuum of 500 micron to
remove moisture and to change a lter-drier. Liquid line
lter-driers must have a working rating pressure of no
less than 600 psig and must be approved for use with
R-410A.
Hoses
R-410A hoses and assemblies should be Underwriters
Laboratories (UL) recognized and have a minimum
800 psi pressure rating with a 4,000 psi burst.
Manufacturers recommend the use of a ball valve type
connection rather than an anti-blowback connector. An
anti-blowback connector traps refrigerant in the hose
making it dif cult to disconnect the hose under high-
pressure conditions. Although most R-410A units come
with the standard 1/4-inch ttings, some manufacturers
use 5/16-inch access ttings.
When buying hoses for R-410A make sure the complete
hose assembly has been recognized by Underwriters
Laboratories. Some hose manufacturers use UL-
recognized hose, but fail to have the complete assembly
certi ed for R-410A pressures. Always use the shortest
hoses possible. Using 3/8-inch hose will greatly increase
the recovery rates.
Recovery refrigerant tanks
A U.S. DOT 400 recovery tank must be used when
recovering R-410A. Recovery tanks have a DOT rating
of 4BA 400 or 4BW 400. A standard DOT 350 recovery
tank will not safely handle the high pressures used with
R-410A. Clearly mark all of the R-410A tanks and have
them re-certi ed every ve years. R-410A refrigerant
tanks must be color coded pink.