Vogt P18AL TUBE-ICE, Service Manual

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P18AL Service Manual
HOW YOUR TUBE-ICE MACHINE WORKS
3/6/2007
4-1
4. How Your Tube-Ice
®
Machine Works
Principle Of Operation
For a detailed description of the functions of each control panel component, see Section 6.
Operation of the machine is controlled by “Clean/Off/Ice”, “Start” and “Stop” switches located in
the control panel of the freezing unit. Automatic operation is controlled by the freeze timer or an
optional ice bin thermostat which will automatically stop and start the ice maker by the level of the
ice in the storage bin. The control wiring is arranged so that the unit will stop only upon the
completion of a thawing period whether by action of the “Clean/Off/Ice” switch in the “Off”
position, by the completion of a timed cycle or by the ice bin thermostat.
The “Clean/Off/Ice” switch must always be set in the “Ice” position during normal ice-making
operation. It is set in the “Clean” position only when the equipment is to be cleaned as outlined in
the “Cleaning Procedure”, Section 7 and instructions attached to the machine.
If it should become necessary to instantly stop the machine, push the “Stop” button. To restart the
machine, push the “Start” button.
FIGURES 4-1 & 4-2 illustrate the piping diagram of the refrigerant and water circuits of the Tube-
Ice
®
machines with numbers for easy reference. Throughout this manual, the numbers you see in
parentheses refer to the numbers in this piping schematic.
The freezer (1) is a shell and tube-type vessel. During the freezing period, water is constantly
recirculated through the vertical tubes of the freezer by a centrifugal pump (5). Make-up water is
maintained by a float valve (29) in the water tank (13). The refrigerant float switch (23) opens and
closes the liquid line solenoid valve (25), sometimes referred to as the “A” valve, is open and
solenoid valve (18), sometimes referred to as the “D” valve, is closed.
Refrigerant gas from the top of the freezer (1) passes through the suction accumulator, and to the
compressor. Here the cool gas is compressed to a high temperature, high pressure gas which
discharges through the oil separator and into the condenser. In the condenser, heat is removed and
the gas is condensed to a high temperature, high pressure liquid. The high pressure liquid goes
through the accumulator boil out coil where it is gives up heat to the suction gas for compressor
protection. In addition, this liquid is subcooled and carried to the Freezer (1). Liquid refrigerant
from the accumulator flows through the thawing chamber of the freezer, the liquid line stop valve
(24), the “A” liquid feed valve (25) and then the hand expansion valve (9). The float switch (23)
is wired to the “A” solenoid valve (25). The float switch energizes and de-energizes the “A”
solenoid in response to the level of refrigerant in the freezer. The cold liquid refrigerant enters the
freezer where it absorbs heat from the circulating water. This cool gas is pulled out of the freezer at
the suction outlet thereby completing the circuit.