Section 7Refrigeration System
7-26
REMOTES ONLY
Harvest Pressure Regulating (H.P.R.) System
GENERAL
The harvest pressure regulating (H.P.R.) system
includes:
1. Harvest pressure regulating solenoid valve
(H.P.R. solenoid)
This is an electrically operated valve which opens
when energized, and closes when de-energized.
H.P.R. Solenoid
2. Harvest pressure regulating valve (H.P.R. valve)
This is a non-adjustable pressure regulating valve
which modulates open and closed, based on the
refrigerant pressure at the outlet of the valve. The
valve closes completely and stops refrigerant flow
when the pressure at the outlet rises above the
valve setting.
H.P.R. Valve
FREEZE CYCLE
The H.P.R. system is not used during the freeze cycle.
The H.P.R. solenoid is closed (de-energized),
preventing refrigerant flow into the H.P.R. valve.
HARVEST CYCLE
During the harvest cycle, the check valve in the
discharge line prevents refrigerant in the remote
condenser and receiver from backfeeding into the
evaporator and condensing to liquid.
The H.P.R. solenoid is opened (energized) during the
harvest cycle, allowing refrigerant gas from the top of
the receiver to flow into the H.P.R. valve. The H.P.R.
valve modulates open and closed, raising the suction
pressure high enough to sustain heat for the harvest
cycle, without allowing refrigerant to condense to
liquid in the evaporator.
In general, harvest cycle suction pressure rises, then
stabilizes in the range of 75-100 psig (517-758 kPA).
Exact pressures vary from model to model. These can
be found in the “Operational Refrigeration Pressures”
charts, beginning on page 7-31.
SV1427
FLO
SV1426
OUTLET INLET
INLET
OUTLET
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