Hitachi Highly WHP05600VUK, Installation Manual

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12 Start-stop frequency
The frequency should be less than 6 times per hour. Operating time from start to stop should
be more than 3 minutes. Stopping time should be more than 3minutes. But oil level should be met
to item 8. Suction and discharge pressure should balance completely before restarting.
13 Rate of rotational speed change
The rate of compressor rotational speed (acceleration) should be less than 133min
-1
/s, But if
The variable range is below 120min
-1
, rate can also be less than 600min
-1
when rotational
Speed is reduced to avoid temporary over- current. The change of compressor rotational speed
is referred to chart 3.
14 Air and moisture in refrigerating system
The degree of vacuum in refrigerating system should be less than 133Pa (998×10
－
3
mmHg) at
room temperature just before charging refrigerant. The quantity of water should be less than 0,15 ml
15 Impurities in refrigerating system
(1) The weight of residue on the inside surface of the heat exchanger and tube should be less
than 0.01g/m
2
. But metallic dust should not be permitted in the system. This value means the
weight of foreign residue collected by filer paper after washing inside surface of the
heat exchanger tubes with R-11.
(1)
Prevent the impurities from entering into the enclosed unit system used . When the impurities
entered into the enclosed system, it will damage the moving mechanism parts and result
in the capillary depositing.
(1)
Eliminate all system contaminants such as trichlorethylene, alkalies, soaps, oil, acids &
washing fluid used at machining heat exchanger and tubes.
16 Compressor vacuum operation
Compressor should never be operated while under vacuum. Otherwise, internal arcing can
cause damaging parts.
17 The compressor should be operated for more than 20 seconds within 15 minutes after charging
refrigerant into the system so proper lubrication results.