Frick SGC 1913 - Volumizer Volume Ratio Control

070.650-IOM (AUG 2015)
Page 22
SGC ROTARY SCREW COMPRESSOR
OPERATION
NOTICE
To control the rate of loading and unloading, throttle
the needle valve at SC1 port.
DOUBLE-ACTING MODE - (Low Differential Application)
Open valve at SC1
Open valve at SC2
Close valve at BP (bypass)
Compressor Loading (Double-acting): The compressor
loadswhenSVsolenoidYY2isenergizedandoilowsfrom
the oil manifold through valve ports P and B to cylinder port
SC2 and enters the load side of the cylinder. Simultaneously,
oilcontainedintheunloadsideofthe cylinder owsout
cylinder port SC1 through valve ports A and T to compressor
suction.
Compressor Unloading (Double-acting): The compressor
unloads when SVsolenoidYY1isenergizedandoilows
from the oil manifold through valve ports P and A to cylinder
port SC1 and enters the unload side of the cylinder.
Simultaneously, oil contained in the load side of the cylinder
owsoutofcompressorportSC2throughvalveportsBand
T to compressor suction.
NOTICE
To control the rate of loading and unloading, throttle
valves SC1 and SC2.
NOTICE
To slow all valve movements - loading, unloading, and
Vi change - throttle valve 2.
CAUTION
NEVER open valve BP and valve SC2 at the same time
during compressor operation.
Figure 24. Solenoid Valve Block
VOLUMIZER VOLUME RATIO CONTROL
Open valve at SC3
Open valve at SC4
Compressor Vi increase: The volume ratio Vi is increased
when MSS solenoidvalveYY3 isenergizedand oilows
from the oil manifold through valve ports P and A to
compressor port SC3, enters the increase side of the
cylinder and overcomes the decreased spring tension.
Simultaneously,oilowsfromSC4portthroughvalveports
B and T to compressor suction.
Compressor Vi decrease: The volume ratio Vi is decreased
when MSS solenoid valve YY4 isenergizedand oil ows
from the oil manifold through valve ports P and B to
compressor port SC4, enters the decrease side of the
cylinder. Simultaneously, oil ows formSC3 port through
valve ports A and T to compressor suction.
TO CONTROL THE RATE OF Vi CHANGE, THROTTLE THE
NEEDLE VALVE AT SC3 PORT.