Bally Refrigerated Boxes BVC Generation C – Direct Drive Air-Cooled – Vertical Air - Manual (Page 31)

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This will flood the condenser until the condensing
pressure increases to a point which will again open
the valve. Other valves regulate the refrigerant at the
outlet of the condenser to provide a similar effect.
These are commonly referred to as
outlet
regulators. There are also combination inlet/outlet
regulators with a differential check valve or other
type of condenser bypass arrangement incorpo-
rated within the valve.
Controls which regulate the flow of refrigerant based
on condenser inlet pressure are typically used in
conjuction with a check valve having a minimum
opening differential across the condenser. Outlet
regulators typically require a check valve with a fixed
pressure differential setting of between 20 and 35
psi. The differential is needed to compensate for
pressure drop through the condenser during flood-
ing and associated discharge piping.
Systems equipped with a condenser flooding
arrangement should always use a receiver having
sufficient liquid holding capacity. Additional liquid
required for flooding is only required during the
winter low ambients and must be stored
somewhere in the system at the higher ambients.
Failure to use an adequately sized receiver will
result in liquid back-up in the condenser during the
warmer summer months. This will cause the
system to develop very high pressures in the high
side resulting in a high pressure safety control trip.
Determining Additional Flooded
Refrigerant Charge
Additional charge will vary with the condenser
design TD and the coldest expected ambient
temperature. Condensers designed for low TD
applications (low temperature evaporators) and
operating in colder ambients will require more
additional charge than those designed for higher TD
applications (high temperature evaporators) and
warmer ambients.
Refer to Table 5 to determine the required added
refrigerant charge at the selected TD and ambient
temperatures.
These charges are based on condensers using Fan
Cycling options with their last fan (Single Row Fan
Models) running or last pair of fans running (Double
Row Fan models).
WARNING: Do not over charge when charging by a
sightglass. Liquid lines feeding the TXV at the
evaporator must have a solid column of liquid (no
bubbles) however bubbles at the sightglass (located
adjacient to the receiver) may be normal due to the
result of a higher pressure drop at that point. Bubbles
could also appear in the glass whenever the
regulating valves start to flood the condenser.
Always record the number of drums or the weight of
refrigerant that has been added or removed in the
system. Overcharged systems may result in
compressor failure as well as other serious
mechanical damage to the system components.
LOW AMBIENT OPERATION
DIFFERENTIAL
CHECK VALVE
ORI / ORD CONDENSER PRESSURE CONTROL
SINGLE VALVE CONDENSER PRESSURE CONTROL
(Regulates inlet pressure or outlet pressure depending on valve design)