GENER
AL INFORMA
TION
PR
ODUC
T INFORMA
TION
INTEGR
ATION INT
O SY
STEM
ORDERING INFORMA
TION
SY
STEM DESIGN
Control logic
Pump-down logic
recommendations
Pump down is initiated prior to shutting
down the last compressor on the circuit by
de-energizing a liquid line solenoid valve
or closing electronic expansion valve. When
suction pressure reached the cut-out pressure,
compressor is stopped, and liquid solenoid valve
or electronic expansion valve remains closed.
Two types of pump-down exist:
• One shot pump down (preferred): when
last compressor of the circuit stops, suction
presssure is decreased 1.5bar (22psi) below
nominal evaporating pressure with minimum
of 1.7bar(g) (25psig). Even if suction pressure
increases again, the compressor will not restart.
• Continuous pump-down: traditional pump-
down, Compressor restarts automatically
when suction pressure increases up to 4 cycles
maximum.
For DSH090 to DSH184, an external Non
Return Valve (NRV) in the discharge line is
recommended. DSH240 to DSH485 compressors
integrate tight internal non return valve (INRV),
therefore no external Non Return Valve (NRV) is
needed.
48
FRCC.PC.045.A7.02
Содержание DSH Series
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