375, 375H, 400HH, 425, 425H T4F User Manual 2: Description
02250223-036 R01
Subject to EAR, ECCN EAR99 and related export control restrictions. 21
mum receiver pressure of 80 psig (5.5 bar) during all
conditions. Keeping this pressure level stable is neces-
sary for proper air/fluid separation and proper fluid circu-
lation. A pressure relief valve (located on the wet side of
the
sepa
rator) is set to open if the sump pressure
exceeds 250 psig (17.1 bar).
Fluid is added to the receiver tank through a capped fluid
filler.
2.6 Capacity control system,
functional description
Refer to Figure 2-5 or Figure 2-6 and Section 2.7 and
Section 2.8. The purpose of the control system is to regu-
late the amount of air intake and match it to the demand
(requir
ed output) on the compressor. The control system
consists of a pressure regulating valve(s), air inlet valve,
system blowdown valve, pressure transducer, speed
control module, and tubing connecting the various com-
ponents of the compressor and engine. The functional
desc
riptions of th
e control system are described by relat-
ing them to four distinct phases of operation. They apply
to any contr
ol system with the exception of those with
specified pressures which are dependent on pressure
requirements. The given values apply to a compressor
with an operating pressure range of 100 to 110 psig (6.9
to 7.6 bar).
Start—0 to 40 psig (0 to 2.8 bar)
When the compressor is started, the sump pressure
quickly rises from 0 to 40 psig (0 to 2.8 bar). During this
peri
od the pressure regulator valve is inactive. At this
pressure range the idle warm-up control keeps the inlet
valve closed for engine idle operation. Within 30 seconds
of starting the compressor (the instrument panel annunci-
ator light goes off after 30 seconds) turn the handle of the
war
m-up selector valve (loca
ted on the instrument panel)
from the START to the RUN position. The inlet valve is
fully open due to inlet pressure, and the compressor
operates at full capacity. When the compressor operates
at full capacity, the engine runs at full speed.
Normal operation—80 – 100 psig (5.6 – 6.9 bar),
80 – 150 psig (5.6 – 10.3 bar) [H models],
80 to 200 psig (5.6 to 13.8 bar) [HH models]
When the warm-up control selector valve handle is
moved to the RUN position, the sump pressure rises
above 80 psig (5.6 bar). At this time, the inlet valve
remains fu
lly open for maximum air output. The engine
will continue to run at full speed during this phase of
operation.
Modulation—100 to 110 psig (6.9 to 7.5 bar),
150 to 165 psig (10.3 to 11.4 bar) [H models],
200 to 220 psig (13.8 to 15.2 bar) [HH models]
If the demand on the compressor is less than its rated
capacity, the service line pressure will rise above
100 psig (6.9 bar) - low or single pressure rating:
150 p
sig (10.3 bar) for “H” rating or 200 psig (13.8 bar)
for “HH” dual or hig
h pressure rating. The pressure regu-
lating valve gradually opens, applying pressure to the
inlet valve pisto
n and pressure transducer. This causes
the inlet valve to partially close and reduces the engine
speed. As the pressure increases, the inlet valve piston
will further close the inlet valve and the engine speed will
decrease until it reaches its preset idle speed. When the
demand on the compressor increases, the sump pres-
sure falls below 110 psig (7.6 bar) or 165 psig (11.4 bar)
fo
r “H” mach
ines, or 220 psig (15.2 bar) for “HH” ones.
The pres
sure regulating valve closes, the air inlet valve
opens fully, and the engine speed increases to its preset
full load rating.
Between the pressure regulating valve and the inlet
valve, there is a
small orifice that vents a small amount of
air into the atmosphere when the pressure regulating
valve is open. This allows changes in air output to con-
form to air demand. This orifice also discharges any
accumu
lated mo
isture from the regulator.
WARNING
Do not remove caps, plugs and/or other compo-
nents when the compressor is running or pres-
surized. Stop the compressor and relieve all
internal pressure
by following proper lockout/
tagout procedures before removing these items.
To Next Page
Loading...
