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below. In case of operation in the (red) unsafe area, adjustments are required in order to modify the
system design, refrigerant charge or superheat setting of the expansion device(s). The bottom shell
temperature should be measured accurately. The thermo-probe must be positioned on the opposite
side of the sight glass or at an angle of 90° clockwise from the suction inlet with view on the top.
3.15 Suction line accumulator
CAUTION
Inadequate lubrication! Bearing destruction! For R450A and R513A
refrigerants, Emerson recommends using suction accumulators, unless it has
been qualified that a suction line accumulator is not needed.
Due to Copeland Scrolls inherent ability to handle liquid refrigerant, for example in flooded start and
defrost cycle operation, an accumulator is not required in most systems.
To determine if a suction line accumulator is required, the system designer must check this with an
appropriate test scenario. See Chapter 3.14 "Compressor oil return, oil balancing and floodback
tests".
If an accumulator is used, the oil-return orifice should be from 1 to 1.4 mm in diameter for all YH*K1E
models depending on compressor size and compressor floodback results. To protect this small orifice
from plugging with system debris a large-area protective screen no finer than 30 x 30 mesh (0.6 mm
openings) is required. Tests have shown that a small screen with a fine mesh can easily become
plugged causing oil starvation to the compressor bearings. The size of the accumulator depends
upon the operating range of the system and the amount of sub-cooling and subsequent head
pressure allowed by the refrigerant control. For the correct selection and size of the suction line
accumulator, refer to the manufacturer's specifications.
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AGL_HP_ST_YHK1E_E_Rev02
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