Liebert CHALLENGER 3000 - Manual (Page 58)

Component Operation and Maintenance
50
High Pressure Valve - 350 PSIG System (2413 kPa) for 3 Ton Units (Metrex Valve)
Adjustment—The valve may be adjusted using a 1/8" diameter rod. Turn adjusting collar nut coun-
terclockwise to raise head pressure. Turn it clockwise to lower head pressure. Rotation directions are
as viewed from top of valve spring housing.
Figure 11 Metrex valve adjustment
Manual Flushing—The valve may be flushed by rotating the socket head screw clockwise. This
screw must be in the OUT position (counterclockwise) for normal valve operation.
Valve Disassembly
1. Shut off the water supply by using isolating valves.
2. Relieve the tension on the main spring by turning the adjusting screw (or collar) as far as it will
go (provide a container to catch water below the valve).
3. Remove four screws extending through the main spring housing.
4. Remove the center assembly screws for access to all internal parts.
5. Clean the seat if possible. If the seat is pitted or damaged, replace the valve rubber disc and valve
seat.
6. After valve is reassembled check for leaks.
7. Readjust head pressure control.
Testing Function of Valve—When the refrigeration system has been off for approximately 10 to 15
minutes, the water flow should stop.
If the water continues to flow, the valve is either improperly adjusted (with head pressure too low) or
the pressure sensing capillary is not connected properly to the condenser.
Glycol Solution Maintenance
It is difficult to establish a specific schedule of inhibitor maintenance since the rate of inhibitor deple-
tion depends upon local water conditions. Analysis of water samples at time of installation and every
six months should help to establish a pattern of depletion. A visual inspection of the solution and fil-
ter residue is often helpful in judging whether or not active corrosion is occurring.
The complexity of water caused problems and their correction makes it important to obtain the advice
of a water treatment specialist and follow a regularly scheduled maintenance program. It is impor-
tant to note that improper use of water treatment chemicals can cause problems more serious than
using none.
Proper inhibitor maintenance must be performed in order to prevent corrosion of the glycol system.
Consult glycol manufacturer for testing and maintenance of inhibitors. Do not mix products from dif-
ferent manufacturers. For further details, refer to filling instructions in the installation manual, Lie-
bert part number SL-11925.
Adjusting Collar Nut