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3.4
Pressure safety controls
Pressure protection devices to be used in ATEX Zone 2 locations must comply with the ATEX
directive requirements. Non ATEX-certified pressure protection devices shall NOT be used in ATEX
Zone 2 locations.
ATEX-approved pressure protection devices are available from Alco Controls. Please refer to the
dedicated "Product Guide for R290".
3.4.1 High-pressure protection
Applicable regulations and standards, for example EN 378-2, shall be followed to apply appropriate
control and ensure that the pressure never exceeds the maximum limit.
High-pressure protection is required to stop the compressor operating outside the allowable pressure
limits. The high-pressure control must be installed correctly, which means that no service valve is
allowed between the compressor and the pressure protection.
The high-pressure cut-out setting shall be determined according to the applicable standard, the type
of system, the refrigerant and the maximum allowable pressure PS.
3.4.2 Low-pressure protection
CAUTION
Operation outside the application envelope! Compressor breakdown! A
low-pressure protection shall be fitted in the suction line in order to stop the
compressor when it operates outside the envelope limits. Do not bridge or by-
pass the low-pressure limiter.
Applicable regulations and standards shall be followed to apply appropriate control and ensure that
the pressure is always above the required minimum limit.
Low-pressure protection is required to stop the compressor operating outside the allowable envelope
limits. The low-pressure control must be installed correctly into the suction line, which means that no
service valve is allowed between the compressor and the pressure protection.
The minimum cut-out setting shall be determined according to the refrigerant and the allowed
operation envelope – see Select software at www.copeland.com/en-gb/tools-resources.
3.5
System protection for operation below atmospheric pressure
WARNING
Operation below atmospheric pressure! Fire hazard! During operation
below atmospheric pressure, a flammable mixture can form inside the system.
Ensure system tightness to prevent any ingress of air.
YB*K1G compressors in R290 systems may be operated below atmospheric pressure only when
installed in hermetically sealed systems. For non-hermetically sealed systems, the pressure must
always be above atmospheric pressure. The operating pressure must be limited as defined by the
operation envelope – refer to the technical documentation.
When YB*K1G compressor systems operate below atmospheric pressure, the following precautions
must be observed.
▪ Check all the critical points on the system and piping connections; tightness has to be ensured
also at very low pressure.
▪ Minimum absolute working pressure: 0.5 bar.
▪ The installation of mechanical high-pressure and low-pressure cut-outs is mandatory. For
systems provided with a service shut-off valve on the discharge side of the compressor, only a
mechanical pressure cut-out shall be used. Electronic pressure limiters, which could cause
delayed sensor response, are not allowed.
▪ The high- and low-pressure cut-outs must be installed correctly on the discharge and suction
lines, which means that no service valve is allowed between the compressor and the pressure
protection (refer to EN 378 or ISO 5149).
▪ A discharge temperature control is mandatory to stop the compressor when the maximum
discharge temperature is exceeded – see section 3.8 "Discharge gas temperature
protection".
AGL_Ref_ST_YBK1G_EN_Rev01
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