Engineering manual - SAB 355 Screw compressor unit (including ATEX)
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004100 en 2020.10
Technical description
prevent flow from the common economiser vessel to the suction side of a stopped compressor,
through the suction check valve bypass line, if the other compressors and the common econo-
miser vessel are still operating and the HV2 valve on the suction bypass is open.
For refrigeration plants using a Packaged Refrigerant Recirculation (PRR) unit and a direct expan-
sion (DX) economiser system, it is necessary to operate the liquid feed solenoid on the PRR unit
and the liquid feed solenoid on the DX vessel off of a common signal to avoid liquid overfeed on
the DX economiser system.
If multiple compressors are operated with a common economiser vessel, it is necessary to install
a back-pressure regulator valve with an electric shutoff option in the vapour line piped to the com-
pressor's economiser port. If an electric shut-off is not installed in the economiser vapour line,
valve HV-2 must remain closed to avoid a gas bypass from the economiser line through the suc-
tion check valve bypass, back to the suction line on a compressor that is shut down.
Fig. 48: Shell and coil economiser system
Fig. 49: Direct expansion economiser system
Fig. 50: Flash economiser system
Fig. 51: Multiple compressor economiser system
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