5.4 Piping the DSP Air Compressor
5.4.1 General Instructions
Stop Valve
Prevent the condensate from flowing back from the main
plant airline pipe.
⑦ If you connect the DSP’s discharge pipe to a main plant
airline pipe, run the discharge pipe upwards and then
downwards before joining to the main plant airline pipe,
to prevent the condensate from flowing back.
From the DSP
Main Plant
Airline Pipe
500mm or more
(50 inches)
① Use the degreased pipe as a plant airline pipe.
② If you connect the DSP directly to a gas pipe, use a
union or flange joint to ease disassembling the DSP
enclosure panels.
Flange Joint
③ If a plant airline pipe is longer, use a larger diameter
pipe taking into consideration the pressure loss
through the pipe.
④ If there is a concaved or upright part in a plant airline
pipe, provide a condensate drain valve at its bottom.
⑤ Install a discharge stop valve on a plant airline pipe
near the DSP.
⑥ If you want to elevate a plant airline pipe near the
DSP, keep a space of 500 mm (20 inches) between
the elevated pipe and the DSP enclosure panel to
ease the maintenance servicing.
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5. INSTALLING AND PIPING THE DSP [Piping the DSP Air Compressor]
Stop Valve
Stop Valve
Discharge
Air
Opened
Closed
Air Receiver Tank
Operating DSP
Non-Operating DSP
Motorized isolation valve
(VSD only)
Motorized isolation valve
(VSD only)
If you operate only one of the two or more DSPs, keep
fully closed the discharge stop valve of the non-operating
DSP.
If you operate the two DSPs alternately and automatical-
ly, use an electric-driven or any other automatic stop
valve, one that can be automatically closed when the cor-
responding DSP has stopped.
If you use a solenoid valve as an automatic stop valve,
consult your Hitachi distributor.
A motorized isolation valve is included as a standard
accessory. Arrange for the motorized isolation valve
to be “closed” while the compressor is stopped.
If not using the motorized isolation valve, when oper-
ating one side, provide a stop valve for the discharge
piping of the compressor that is not running and close
it completely.
Assume that one DSP is operating and another is not. In
case that the discharge stop valve of the non-operating
DSP is opened, a back pressure is applied on that DSP ’s
aftercooler, check valve, etc. As a result the condensate is
produced much more than otherwise; even the Aftercooler
is rusted internally and the check valve is earlier rusted.
IMPORTANT
5.4.2 Two-Unit Parallel Piping / Operation
IMPORTANT
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