Vogt P-34AL-15 Service Manual Download

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P34AL-15 & P34ALOF-15 Service Manual

HOW YOUR TUBE-ICE MACHINE WORKS

9/22/05

4-1

4. How Your Tube-Ice Machine Works

Operating Features.

Your Vogt low side Tube-Ice

machine is an efficient ice producing plant. If

installed and maintained properly, it will give many years of operation with a minimum amount of
repairs. Refer to piping schematics, FIGURE 4-1 and 4-2 to identify component parts while
following the information and instructions in this manual.

The machine is manually started and stopped by the START and STOP push buttons. The machine
will automatically stop by safeties such as, cutter and pump overloads, as well as other auxiliary
motor overloads. It will also stop automatically by high head pressure, low suction pressure (if field
wired to the high side). The circulating water pump can be operated independently for chemically
cleaning the freezer tubes and water tank by use of the HAND/AUTO selector switch. The machine
can be manually forced into a harvest cycle with the manual harvest push button.

Principle of Operation.

The freezer (2) is a shell and tube-type vessel. During the freezing period

(cycle), water is constantly recirculated through the vertical tubes of the freezer by a centrifugal
pump (6). The make-up water level is maintained by a float valve (12) in the water tank (7). The
refrigerant float switch (10) opens and closes the liquid feed “A” solenoid valve (20) and maintains
the desired refrigerant level in the freezer (2) (Flooded units only).
Refrigerant gas from the top of the freezer (2) passes through the suction accumulator (88) to the
suction header and back to the compressor. The cool gas from the evaporator is compressed to a high
temperature, high pressure gas which discharges through the oil separator (then through the heat coil
of the receiver, when installed) and to the condenser. In the condenser, heat is removed and the gas
is condensed to a high temperature, high-pressure liquid. The high-pressure liquid passes through
the liquid line through a strainer (43), liquid “A” solenoid valve (20) check valve (101), and hand
expansion valve (17). At the hand expansion valve (17), the refrigerant expands from a saturated
high-pressure liquid state to a low pressure, low temperature liquid. This cold liquid enters the
freezer (2) where it absorbs heat from the circulating water in the freezer tubes. Cool gas is again
pulled out of the freezer through the suction outlet, thereby completing the circuit.

The freezing period is completed by action of the freeze timer (1TR) in the control panel. The water
pump (6) stops and the “A” solenoid valve (20) closes. After a delay of 20-30 seconds, the cutter
motor starts, the thawing gas “D” solenoid valve (18R) opens, and the harvest (thawing) timer (2TR)
is activated. Warm gas from the receiver is discharged through the thawing chamber (16), check
valve (101), and into the freezer. There it warms the refrigerant and the outer surface of the freezer
tubes, allowing the ice to release on the inside of the tubes and drop down onto the rotating cutter for
sizing. After sizing, the ice drops on the tines cutter disc and is discharged through the ice discharge
opening.

See “Freeze Period” and “Harvest Period” for more detailed description of machine.

Freeze Period.

The Tube-Ice

is frozen inside the stainless steel tubes of the freezer (2) by the

direct application of refrigerant to the outside shell side of the tubes. Ice is produced from
constantly recirculating water down each tube. As the ice thickness increases, the freezer suction
pressure decreases. At a set time the freeze timer (1TR) energizes the relay (1CR), which stops the
water pump, closes the “A” liquid feed solenoid valve (20), de-energizes the suction regulator (when
installed), turns out the two pilot lights, ammonia feed and freezing.