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8
LOW AMBIENT BY–PASS VALVE
The HazardGard unit is designed to operate at
low outside ambient temperatures. This is
accomplished by the use of a bypass valve
installed in the refrigeration circuit. The valve is
connected between the discharge line at the
compressor and the suction process tube. The
valve responds to suction pressure which, when
reduced in the system, causes the valve to open
and bypass hot gas from the high pressure side
to the low pressure side of the system. The hot
gas entering the compressor mixes with the cool
gas returned through the suction line, thus
increasing the suction pressure. The valve is
preset to open when the suction pressure reaches
50 psig. This pressure setting cannot be altered.
The system can be operated at outdoor
temperatures as low as 45°
F before the
evaporator coil will begin to accumulate frost.
To determine if the valve operates, block the return
air to the evaporator coil. Turn on the unit and
touch the tube at the bypass valve outlet which
connects to the suction process tube. When the
low side pressure reaches approximately 50 psig,
the valve will begin to open and the tube will get
hot. This method will determine if the valve is
responding to the suction pressure change.
FIGURE 8
LOW AMBIENT Bypass VALVE
1. Voltmeter
2. Ammeter
3. Ohmmeter
4. E.P.A Approved Refrigerant Recovery System
5. Vacuum Pump (capable of 200 microns or
less vacuum).
6. Acetylene Welder
7. Electronic Halogen Leak Detector G.E. Type
H-6 or equivalent).
8. Accurate refrigerant charge measuring device
such as:
a. Balance Scales - 1/2 oz. accuracy
b. Charging Board - 1/2 oz. accuracy
9. High Pressure Gauge - (0-400 lbs.)
10. Low Pressure Gauge - (30" - 150 lbs.)
11. Vacuum Gauge - (0-1000 microns)
EQUIPMENT MUST BE CAPABLE OF:
1. Recovering CFC’s as low as 5%.
2. Evacuation from both the high side and low
side of the system simultaneously.
3. Introducing refrigerant charge into the high
side of the system.
4. Accurately weighing the refrigerant charge
actually introduced into the system.
5. Facilities for flowing nitrogen through the
refrigeration tubing during all brazing
processes.
SEALED REFRIGERATION SYSTEM
REPAIRS
EQUIPMENT REQUIRED