Vogt P-34AL-15 Service Manual Download

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P34AL-15 & P34ALOF-15 Service Manual

START-UP & OPERATION

9/22/05

5-1

5. Start-Up & Operation

Refrigeration System Review.

The refrigeration system uses anhydrous ammonia (R-717)

refrigerant. Following the piping schematic (Figure 3-11 to 3-17 and 4-1 or 4-2), you will see that
during the machine’s freeze cycle, the compressor discharge gas goes through the oil separator to
remove any oil present in the discharge gas and return the oil to the compressor crankcase. It is then
discharged into the condenser and condensed into a liquid by the removal of heat by water passing
through the condenser tubes. A reservoir of liquid R-717 (800 lbs. for P34AL-15) is accumulated in
the receiver and is required for thawing purposes (see Table 3-2). Liquid from the receiver flows
through the strainer to the “A” solenoid valve (20), which opens and closes by action of the low side
float switch (10), flooded unit only. The liquid is then expanded through the hand expansion valve
(17) and into the evaporator (2) (freezer). The cold wet R-717 refrigerant floods the evaporator and
is in contact with the outside of the ice making tubes which water is being circulated through. The
heat contained in the water passes through the wall of the tubes, lowering the temperature of the
water causing it to freeze and form a long tube of ice that adheres to the inside of freezer tubes.
Since the purest water freezes first, the circulating water continues to wash the dissolved solids
down into the sump area of the water tank. The flushing valve helps to rid the water tank of
increased dissolved solids by flushing them out the overflow during the harvest (thawing) period.

The wet suction gas leaves the freezer and passes through the suction accumulator (88), where liquid
droplets are removed, and allowing dry gas to enter the suction side of the compressor. The suction
gas is then compressed and discharged once again, completing the cycle. As ice continues to form in
the freezer tubes, the suction pressure steadily decreases, when the freeze timer (1TR) times out the
contact closes, initiating the thaw (harvest) cycle.

Note: Freezing time will vary, depending on make-up water temperature, suction pressure and
thickness of ice produced. The freeze timer (1TR) should be set to provide the correct time to
produce ice at the required thickness under the current operating conditions.

During the harvest period, the “D” thawing gas valve (18) opens, the suction valve (field installed)
and the compressor unloads (when required), allowing the warm high-pressure gas from the receiver
to enter the freezer. As the tubes warm up to slightly above freezing (approximately 40

F / 5

C),

the ice inside the tubes releases and falls down onto the rotating cutter for sizing and discharging.
Harvesting requires about three minutes, but can vary depending on ice thickness, suction pressure,
discharge pressure (thawing gas temperature) and distance from the receiver to the freezer.

! IMPORTANT !

It is a good idea and will be profitable for you to observe and

become familiar with the proper operating characteristics of your

Tube-Ice

machine. It will help you to recognize and correct minor

irregularities as they occur in order to help prevent major problems.

“An ounce of prevention is worth a pound of cure.”

! IMPORTANT !