Manitowoc J-1300, Руководство по обслуживанию

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Section 7 Refrigeration System
7-17
HOT GAS VALVE TEMPERATURE CHECK
General
A hot gas valve requires a critical orifice size. This
meters the amount of hot gas flowing into the
evaporator during the harvest cycle. If the orifice is
even slightly too large or too small, long harvest
cycles will result.
A too-large orifice causes refrigerant to condense to
liquid in the evaporator during the harvest cycle. This
liquid will cause compressor damage. A too-small
orifice does not allow enough hot gas into the
evaporator. This causes low suction pressure, and
insufficient heat for a harvest cycle.
Normally, a defective hot gas valve can be rebuilt.
Refer to the Parts Manual for proper valve
application and rebuild kits. If replacement is
necessary, Use only “original” Manitowoc
replacement parts.
Hot Gas Valve Analysis
Symptoms of a hot gas valve remaining partially open
during the freeze cycle can be similar to symptoms of
either an expansion valve or compressor problem.
The best way to diagnose a hot gas valve is by using
Manitowoc’s Ice Machine Refrigeration System
Operational Analysis Table.
Use the following procedure and table to help
determine if a hot gas valve is remaining partially
open during the freeze cycle.
1.
Wait five minutes into the freeze cycle.
2. Feel the inlet of the hot gas valves.
Important
Feeling the hot gas valve outlet or across the hot
gas valve itself will not work for this comparison.
The hot gas valve outlet is on the suction side (cool
refrigerant). It may be cool enough to touch even if
the valve is leaking.
3. Feel the compressor discharge line.
WARNING
The inlet of the hot gas valve and the compressor
discharge line could be hot enough to burn your
hand. Just touch them momentarily.
4. Compare the temperature of the inlet of the hot
gas valves to the temperature of the compressor
discharge line.
Findings Comments
The inlet of the hot
gas valve is cool
enough to touch
and the
compressor
discharge line is
hot. This is normal as the discharge
line should always be too hot
to touch and the hot gas
valve inlet, although too hot to
touch during harvest, should
be cool enough to touch after
5 minutes into the freeze cycle.
The inlet of the hot
gas valve is hot
and approaches
the temperature of
a hot compressor
discharge line. This is an indication something
is wrong, as the hot gas valve
inlet did not cool down during
the freeze cycle. If the
compressor dome is also
entirely hot, the problem is not
a hot gas valve leaking, but
rather something causing the
compressor (and the entire ice
machine) to get hot.
Both the inlet of the
hot gas valve and
the compressor
discharge line are
cool enough to
touch. This is an indication something
is wrong, causing the
compressor discharge line to
be cool to the touch. This is not
caused by a hot gas valve
leaking.