20
significantly cooler RGTs will have a slight decrease in
compressor capacity when compared to the published
06CC Model Performance tables.
1.15 Suction Line Accumulators
The design of Carlyle’s 06CC model compressors draw
suction gas directly into the low-stage cylinders. Labora-
tory testing has shown that the valves are tolerant to liq-
uid flooding; however, extreme flooding and liquid “slugs”
may cause damage to the compressor. All 06CC models
must be protected from liquid refrigerant and oil “slugs.”
1.16 Single Compressors and Multiple
Compressor System
All single 06CC compressor systems require the applica-
tion of a suction line accumulator. All multiple 06CC com-
pressor systems require the use of a suction line
accumulator or functionally equivalent protection such as
an over-sized suction line manifold. Carlyle recommends
that a suction line accumulator is applied.
1.17 Control Scheme
Properly designed control systems are important to
ensure reliable and efficient 06CC compressor operation.
Please review the following control scheme designs:
Single-Compressor Systems (Fig. 8)
Carlyle requires that single, 06CC compressor systems
are applied with a discharge pressure regulating valve.
Discharge pressure regulating valves prevent the dis-
charge pressure of the compressor from falling below the
required minimum pressures (70 SDT equivalent) in sys-
tems that do not utilize condenser fan controls.
Multiple-Compressor Systems (Fig. 9)
Carlyle strongly recommends that R-22 systems utilizing
multiple / parallel 06CC compressors are applied with a
discharge pressure regulating valve. Carlyle requires that
all HFC / POE systems utilizing multiple / parallel 06CC
compressors, are applied with a discharge pressure reg-
ulating valve (or functional equivalent such as condenser
fan controls). The application of these discharge pres-
sure controls prevents the discharge pressure of the
compressor from falling below the required minimum
pressures (70 SDT equivalent).
1.18 De-Superheating Expansion
Valves
Liquid injection is required for some applications to con-
trol discharge gas temperatures. Liquid injection is
accomplished through the use of Carlyle recommended
de-superheating expansion valves. These valves are
designed to operate only when the suction gas from the
subcooler cannot absorb enough heat to control the com-
pressor's leaving discharge gas temperatures between
200 F and 230 F. See Section 6.0.
If a de-superheating valve is applied, a normally closed
liquid line solenoid valve must be installed prior to the de-
superheating valve (with the sensing bulb attached to the
discharge tubing approximately 6 inches from the dis-
charge service valve). This solenoid valve must be con-
trolled to close whenever the associated compressor is
OFF. De-superheating valves are directly connected to
the 4-bolt flange at the motor end cover of the
compressor.
1.19 Interstage Check Valves
Interstage check valves are no longer required with
Carlyle's 06CC model compressors.
1.20 Capacity Control
Suction cut-off unloading is not available with Carlyle's
06CC models. Variable frequency motor drives may be
applied with Carlyle's 06CC models to provide some sys-
tem capacity modulation. The approved speed range for
06CC models applied with variable frequency drives is
between 30 Hz and 60 Hz. Operating at speeds less than
30 Hz is not recommended due to the potential for lower
net oil pressure and nuisance 'trips' of the oil pressure
safety switch.
1.21 Low-Stage Discharge Gas
Temperatures
The gas compressed in the low-stage heads is typically
superheated and the temperatures will generally be
between 100 F and 200 F. This superheated gas mixes
with the suction gas from the subcooler and with injected
liquid (when high-stage discharge gas temperatures
exceed 230 F) and is ported to the high-stage suction
passages. The high-stage gas temperatures are con-
trolled by liquid injection valves (discussed earlier).
1.22 Cylinder Head Cooling Fans
The use of cylinder head cooling fans is recommended
for all R-22 and R-407A applications. These fans are
effective at de-superheating the interstage and reduce (or
eliminate) the need for supplementary liquid injection.
1.23 External De-Superheating
The use of external de-superheating (other than the rec-
ommended head cooling fan) is not recommended or
allowed.
