Hitachi NEXT Series Service Manual page 22

Aftercooler side
Ball valve (2)
Ⓔ
Ⓕ
Ⓓ
Ball valve
Ⓒ
(1)
Three-way change valve
Ⓑ
Ⓐ
Intercooler side
20
■ Depressurizing the System
Before cleaning the drain pipe, intercooler,
aftercooler, control line filter, or replacing the check
valve, reduce the internal pressure to 0 (zero) by
opening the condensate drain.
compressor and disconnect the main power. Close
the stop valve of the compressed air discharge.
Remove rear panel (1) [Ref No. 911] and rear panel
(3) [Ref No. 913].
(1) Intercooler side
Turn the three-way change valve from Ⓐ to Ⓑ.
(2) Aftercooler side
Turn the ball valve (1) from Ⓒ to Ⓓ. And Turn the
ball valve (2) from Ⓔ to Ⓕ.
Verify that the interstage pressure (INTSTG.P) and
discharge pressure (DIS PRESS) is 0(zero) on the LCD
monitor. In addition, remove the parts slowly because
the pressure is still remained in air pipings due to the
wrong operation or piping works.
Stop the air