Vogt TUBE-ICE P-118F, Service Manual

Page: 75 / 115

P118F Service Manual
SERVICE OPERATIONS
1/6/09
9-5
If it becomes necessary to install a new high/low pressure switch, the following procedure is
recommended for its adjustment:
Turn the adjusting screws clockwise to raise the pressure setting. Turn counter-clockwise to lower
the setting. Adjust the switch to the indicated pressure settings and test with an accurate gage to be
sure the switch functions properly before installation.
Head Pressure. The head pressure should be maintained at 190-210 psig during the freeze cycle.
This pressure can be checked at the test connection in the high pressure line near the high-low
pressure switch.
Water-Cooled Units. A water regulating valve (FIGURE 9-3A) located in the condenser water
inlet line is used to control the water flow through the condenser. This valve should be adjusted to
maintain a head pressure of 195 psig. Increasing the water flow lowers the head pressure and
decreasing the water flow raises the head pressure. The valve is adjusted during the factory test.
The valve stem should not be opened as far as it will go or the valve will not close fully when the
head pressure drops below its setting.
Air-Cooled Units. The condenser fan switch mounted to the frame (lower right side) (FIGURE
9-3B) (CPS) is used to regulate the head pressure. This is an adjustable pressure switch located on
the right-hand front of machine. It controls the operation of the condenser fan motor(s) through a
contactor (FC) (FIGURE 6-1) located in the control panel. The switch is set to cycle the fan
motor(s) “On” at 210 psig and “Off” at 190 psig. Higher settings may be necessary for 0
°
F and
below ambient conditions to assure there is enough warm gas for ice harvesting.
FIGURE 9-3A. Water Regulating Valve FIGURE
9-3B. Condenser Fan Switch
Compressor Crankcase Heater. When electrical power is supplied to terminals L1, L2 & L3 of
the control panel, the crankcase heater is energized when the machine is not operating. It is de-
energized when the compressor is operating.