Vogt P18AL TUBE-ICE, Service Manual

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P18AL Service Manual
INSTALLING YOUR TUBE-ICE
®
MACHINE
3/6/07
3-4
Suction Pressure Regulator
When a P18AL is attached to a central system a pressure
regulator will be required (see Figures 3-3 for location). This regulator (usually furnished by the
purchaser) must be a combination back pressure regulating and stop type valve. The usual
minimum pressure drop across this type valve is 2 psig, therefore the valve must be set to maintain a
freezer pressure at least 2 psi above the maximum general suction pressure.
Compressor Unloading
When a P18AL is attached to a dedicated compressor system
unloading of the compressor will be required. A minimum compressor unloading during the harvest
cycle is 66%. If the compressor can not be unloaded then a hot gas bypass to the suction line must
be installed.
Safety Valves
Two safety pressure relief valves are an integral part of the packaged Tube-Ice
®
machine. They are located on the suction accumulator of the freezer. Vent each of the pressure
relief valves to the atmosphere in such a manner as to comply with local and national codes. Refer
to the International Institute of Ammonia Refrigeration (IIAR) standard for specific requirements
and instructions.
Cooling Tower
When selecting a cooling tower, careful attention must be given to operating wet
bulb conditions. It is advisable to check with your local cooling tower distributor for their
recommendations based on actual operating conditions in your area. An average wet-bulb of 78
°
F is
typical in the U.S. but many localities have design wet-bulbs as low as 72
°
F or as high as 82
°
F.
The cooling tower water pump must be capable of delivering the required volume of water through
the condenser. Due to cooling tower location and pressure drop through water lines and water
regulating valves, the pump must be sized for each installation. Refer to TABLE 11-4 for condenser
water requirements. The water piping for the cooling tower and the installation of the pump must be
in accordance with the manufacturer’s instructions.
Proper water treatment for the prevention of mineral and foreign matter accumulation in the
condenser or cooling tower is recommended. A water analysis should be obtained to determine the
proper chemicals to use.
The condenser water pump should be sized on GPM required for condenser at 80 ft. total discharge
head for a typical installation. However, due to cooling tower location and pressure drop through
water lines, the water pump should be sized for each installation.
If the condenser inlet water temperature is expected to be below 75
°
F/24
°
C, a water regulating valve
should be installed in the condenser water inlet line and adjusted to maintain a head pressure of not
less than 175 psig.