- 21 -
The compressor is provided with a pneumatic
regulating system and a blow-off valve (BOV) which
is integrated in the unloader assembly (UA). The
valve is closed during operation by outlet pressure of
the compressor element and opens by air receiver
pressure when the compressor is stopped.
When the air consumption increases, the air receiver
pressure will decrease and vice versa. This receiver
pressure variation is sensed by the regulating valve
(RV) which, by means of control air to the unloader
assembly (UA), matches the air output to the air
consumption. The air receiver pressure is maintained
between the pre-selected working pressure and the
corresponding unloading pressure.
When starting the compressor, the throttle valve (TV)
is kept closed via receiver pressure. The compressor
element (CElp CEhp) takes in air and pressure builds
up in the receiver (AR). The throttle valve (TV) is
closed. The air output is controlled from maximum
output (100%) to no output (0%) by:
1. Speed control of the engine between maximum
load speed and unloading speed (the output of a
screw compressor is proportional to the rotating
speed).
2. Air inlet throttling.
If the air consumption is equal to or exceeds the
maximum air output, the engine speed is held at
maximum load speed and the throttle valve (TV) is
fully open.
If the air consumption is less than the maximum air
output, air receiver pressure increases and the
regulating valve supplies control air to throttle valve
(TV) to reduce the air output and holds air receiver
pressure between the normal working pressure and
the corresponding unloading pressure. Unloading
pressure = normal working pr 1 bar (14.504
psi).
When the air consumption is resumed, the blow off
valve (BOV) closes and the throttle valve (TV)
gradually opens the air intake and the electronic speed
regulator increases the engine speed.
The construction of the regulating valve (RV) is such
that any increase (decrease) of the air receiver
pressure above the pre-set valve opening pressure
results in a proportional increase (decrease) of the
control pressure to the throttle valve and the
electronic speed regulator.
Part of the control air is vented to atmosphere, and
any condensate discharged, through the vent holes.
Summary of Contents for XRVS 1300 CD7
Page 2: ......
Page 20: ... 20 PNEUMATIC REGULATING SYSTEM AR RV CEhp CElp BOV TV UA ...
Page 95: ...Dataplate 95 ...
Page 100: ... 100 ...
Page 101: ......
Page 102: ......