Warren Controls PICV Series - Manual

This document covers the installation, operation and maintenance
of Series PICV (Pressure Independent Control Valves). The Series PICV
maximizes efficiency and energy savings by providing precise control
of maximum differential temperatures across a coil or heat exchanger
independent of variations in system pressure. The Series PICV
consists of two functional controlling segments. The first segment
is an electrically actuated control valve, capable of responding to
a control signal from a controller that is not part of the PICV. The
second segment is connected in series with the first, and serves to
sense and regulate a preset flowing differential pressure across the
control valve segment. Both segments include pressure balanced
control elements of industrial quality manufactured in accordance
with ISO 9001. The PICV has a rangeability of 50:1, meaning that good control performance can be achieved when the minimum flow
requirement is as low as 1/50 of the maximum flowing GPM (LPS). A
wide range of sizes, materials of construction, pressure ratings and
control characteristics provide flexible configuration to meet almost
any specification or system requirement. The Series PICV is factory
assembled, complete with sensing lines, check valve pressure taps,
and actuators, and is ready for field installation as a complete unit. The
Series PICV is pre-calibrated to a customer-specified set differential
pressure from 2-8 PSIG (0.14-0.55 BARG), and includes a means for
calibration adjustment. A separate, customer supplied, differential
pressure gauge may be installed between the check valve pressure
taps on the PICV to allow for monitoring of the set differential pressure.
SERIES PICV
(Pressure Independent Control Valve)
TABLE OF CONTENTS
Overview / Operation .................... COVER
Configurations ...........................................2-3
Differential Pressure..............................4-8
Installation ...................................................8-9
Dimensions .......................................... 10-12
Weights .........................................................13
Maintenance ...............................................13
Water Quality ..................................... 13-14
VM5000E & VM1500E................ 15-22
TR5000X ............................................. 23-27
DPRV Actuator ..........................................28
Parts/Overhaul ................................. 32-37
Stem Adapter Setting Gages ..............38
HIGH CAPACITY
NOTE: The maximum differential pressure across the entire PICV is
approximately 2 x (Set Differential Pressure) at max flow
PICV IOM
PICV_IOM_REVF_0114
One of the primary factors that influence the flow of fluid through a
control valve is the amount of pressure, or differential pressure across
it. At any point in valve plug travel, flow through a valve will typically
increase if differential pressure is raised, and decrease if it is lowered.
A change in pumping pressure can therefore produce a change
in rate of flow that is not related to the system controller’s output
signal. With pressure independence, the amount of water flowing
through a valve and the controlled load (i.e. heat exchanger coil) is
more accurately controlled as a function of the control signal, and is
less dependent upon varying pump pressure. Stability in the control
system is enhanced when pressure independence is provided, and the
control valve’s installed flow characteristic more closely resembles its
inherent, or constant-pressure characteristic.
The Series PICV (Pressure Independent Control Valve) consists of
two functional controlling segments. The first segment is a pressure-
balanced control valve, actuated by either a high-thrust electric motor
actuator or pneumatic diaphragm actuator. The electric actuator
provides precise positioning of the valve closure mechanism, and
responds quickly and precisely to the electronic control signals
supplied to them. The second segment is a differential pressure control
valve that operates independently of the control valve segment.
This segment is self-powered (self-operating) and does not burden
or interact with the building automation control system. By quickly
raising or lowering its own resistance to flow, the differential pressure
control segment of the PICV regulates and stabilizes the pressure drop
across the control valve segment by absorbing unused head pressure.
This compensates for changes in pumping pressure resulting from
pump switching or from varying flow demands in it’s own,
or parallel flow paths and results in pressure independent
operation.
OVERVIEW
OPERATION