44
5. INSTALLING AND PIPING THE DSP [Piping the DSP Air Compressor]
5.4 Piping the DSP Air Compressor
5.4.1 General Instructions
5.4.2 Parallel piping
⑥
If the compressed air piping near the air compressor is
to be elevated, keep a space of 20 inches (500 mm)
between the elevated piping and the enclosure for ease
of maintenance (see figure below)
Discharge valve
Drain valve
Prevent the backflow of condensate from the plant
compressed air system back to the air compressor.
Approx. 20 inches
(500 mm) or more
Stop valve
Motorized isolation valve
Air receiver tank
Stop valve
Open
Operating
Stop
Close
Discharge
air
Motorized isolation valve
If one air compressor is operated, close the stop valve of
the stopped air compressor. For automatic operation,
such as lead/lag and multi unit controlled, replace the
stop valve to an optional motorized isolation valve.
Ensure that the motorized isolation valve is closed while
the compressor is not running. If you use a solenoid
valve as the automatic stop valve, consult your Hitachi
distributor or local Service Station given on the rear
cover.
Contact the local HITACHI distributor/master dealer or
representative office for more detail.
As shown in the figure above, when one compressor is
operating and the other is stopped with opening the stop
valve, back pressure is applied to the aftercooler and
check valve of the stopped air compressor. This may
cause more condensate going into the air compressor
and more rusting of aftercooler and check valve.
①
Use the degreased pipe as a plant airline pipe.
②
Install an isolation stop valve on the compressed air
outlet pipe (see figure below). Close the isolation
stop valve when stopping the air compressor.
Discharge air
Stop valve
③
Using flange joint to connect the air compressor to an
existing compressed air piping installation allows for
minimal disassembly of the enclosure panels (see figure
above).
④
If the plant compressed air piping installation is
extensive in length, using a larger diameter pipe
assists in lowering pressure drop throughout the
piping system.
⑤
If there is an area in the compressed air piping that is
concaved or vertical (see figure below), provide a
condensate drain valve at its bottom as a drip leg.
IMPORTANT
IMPORTANT
⑦
If the air compressors discharge pipe is connected to
the main compressed air piping, run the discharge up
above the main compressed air piping and then down
into the top of the main compressed air piping (see
figure below). This prevents the backflow of
condensate.
From air compressor
Main compressed air pipe
