Vogt P-24AL Service Manual Download

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P24AL & P34AL Service Manual

START-UP & OPERATION

12/2016

5-1

5. Start-Up & Operation

Refrigeration System Review.

The refrigeration system uses anhydrous ammonia (R-717)

refrigerant. Following the piping schematic (Figures 3-12 to 3-16 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 (approximate 325 lbs for P24AL and 625
lbs. for P34AL) 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 (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  through which water is being
circulated.    The  heat  contained  in  the  water  passes  through  the  wall  of  the  tubes,  lowering  the
temperature of the water, causing it to freeze and to 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  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 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 !