Pcv Sizing - Price PCV Series Manual

PRESSURE CONTROL VALVE
PRODUCT OVERVIEW
Pressure Control Methods
Throttling Method
Throttling applications are used to
isolate low pressure branches of
ductwork from the rest of a system
operating at a higher duct static
pressure. Usually these branches serve
VAV diffusers which require a much
lower inlet static pressure compared
to traditional VAV terminal units due to
the noise higher than recommended
pressures due to the noise generated
by higher than reccomended inlet static
pressure.
Throttling applications work by using the
PCV to hold back excess pressure from
the system to the low pressure branch it
is isolating. This means that as pressure
because of VAV diffusers modulating closed, the PCV damper begins to close to limit airflow into the downstream duct. When the
VAV diffusers begin to open to more allow airflow out of the duct and into the occupied space, the pressure in the duct will begin
to drop, and the PCV damper will begin to open to maintain a constant duct pressure to feed the diffusers.
NOTE: This method can only be used in conjuction with a system bypass PCV or VFD on RTU controlling the duct static for the
whole system; throttling PCV applications are for isolating low pressure branches on a higher pressure system only
FIGURE 1.3 - THROTTLING METHOD (SEQUENCE 1551)
Return

PCV Sizing

To size PCVs correctly, they should be able to bypass 2/3's of the
system design airflow at 1000 - 1500 FPM.
This means that a system with 6000 design CFM would need a PCV
capable of bypassing 4000 CFM which would require a damper whose
area is 2.67 to 4 square feet. In square inches, this is 384 to 576 (there
are 144 square inches in 1 square foot). Based on the area calculated,
a rectangular damper anywhere from 24 x 16 (384 in sq - higher side
of velocity range) to 28 x 20 (560 in sq - lower side of velocity range -
recommended) can be used.
PCV Damper Area in² =
NOTE: We recommend calculating the damper size required with the
low velocity first and if the damper size doesn't fit within the physical
constraints of the job, only then increasing the velocity up to a maximum
of 1500 FPM
priceindustries.com | PRESSURE CONTROL VALVE - Manual
Pressure Control Valve
Supply
Static Pressure Tubing
P Static Pressure Sensor
P
* 144
3