Operation - Trane CXPA Installation Operation & Maintenance

Split system evaporator unit - 5 to 50 ton
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High Pressure Control Valve - Head
Master Alco
Specifically developed to keep the proper
pressure of the air-cooled condenser
during periods of low conditions of
external environment.
General
The air-cooled condensers application for
operation during the whole year or during
low temperatures periods requires some
means of control to keep condensing
pressures that assure a proper system
operation. It is essential that the proper
pressure of the refrigerant liquid is
controlled to:
1. Keep the liquid subcooling and avoid
gas bubbles in the liquid line.
2. Provide an adequate pressure at the
admission side of the thermostatic valve
Fig.02 - direction of gas inlet on valve
10

Operation

to obtain a sufficient drop pressure by
means of the valve gate.
Without a proper condensing pressure
control, serious consequences like bad
cooling and components damage may
occur. Alco Head Master control offers
an efficient and economical method to
solve this usual problem in the industry
of air-cooled condensers.
Operation
The pressure control valve (Head Master)
is a three-way modulated valve controlled
by the high pressure. The loaded cupula
makes a constant pressure over the top
of the diaphragm. In high temperature
environments, the gas derivation that
enters in gate B is admitted under the
diaphragm where it puts itself against
the load pressure of the cupula. The gas
pushes the diaphragm up and allows the
support disc to close the superior
support, preventing the flow of the gate B
(discharge gas), while the flow coming
from gate C does not stand restrictions.
When the room temperature falls, the
air-cooled condenser goes by a
corresponding decrease in the high
pressure.
As
the
high
(derivation) falls, it stops putting itself
against the cupula load pressure and the
diaphragm moves downwards, moving
the stem and the support disc towards
the lower support.
Important
This allows that the discharge gas
(derivation) is dosed inside the receptor,
generating a higher pressure in the
discharge of the condenser. The higher
pressure in the condenser discharge
reduces the flow coming from gate C
and makes the level of condensate liquid
raise in the condenser.
Fig. 03 - High pressure control valve
SSC-SVN001F-EN
pressure

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