What is a Pressure Regulator?

What is a Pressure Regulator?
What is a Pressure Regulator?
Definition
A Pressure Regulator is a mechanical device designed
to regulate system flow pressure in response to
upstream or downstream pressure changes.
Principles of Operation
Trerice Pressure Regulators are available in two basic
configurations: a one-piece design with an integrated
actuation system, or a two-piece design comprised of
individual components (actuator and globe valve), which
are factory assembled into a complete regulator.
One-Piece Design
Pressure Regulators & Acc.
One-Piece Pressure Regulators (Series 984, 988,
1002) have an internal diaphragm that is attached to a
valve plug. The diaphragm is balanced between the
downward force of an adjustment spring and the upward
force of the reduced downstream pressure within the
regulator. As the downstream pressure decreases, the
adjustment spring pushes down on the diaphragm,
which in turn opens the valve. Conversely, as
downstream pressure increases, the diaphragm is
forced upward, overcoming the force of the spring and
closing the valve.
Two-Piece Pressure Regulators (Series 91500, 921)
employ a user-supplied pressure line connecting the
actuator to the point of regulation within the pipeline or
process. Depending upon the model selected, the process
pressure will either expand a bellows or depress a
diaphragm within the actuator housing. The subsequent
movement of the bellows or diaphragm will push an
attached valve stem to the “in” position. Choice of a
stem In-To-Close or stem In-To-Open globe valve will
determine if the assembled pressure regulator is for
reducing downstream pressure (ITC or normally open) or
relieving upstream pressure (ITO or normally closed).
These units feature spring-opposed actuation: when the
controlled pressure decreases, the adjustment spring will
push the diaphragm upward or compress the bellows,
which will in turn move the valve stem back to the “out”
position.
Two-Piece Design
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What is a Pressure Regulator?
continued
Selecting a Pressure Regulator
•
•
Trerice 91500 Series Pressure Regulators are specifically designed
for use on retorts and cooking vessels used within the food processing
industry. Valve sizes from 1/2" through 4" port are available.
•
Trerice 984 Series Pressure Regulators are designed to provide
pressure regulation of steam, air, water, gas or oil. They are used primarily
for small load process equipment and service line applications. Valve
sizes from 1/4" through 1/2" port are available.
•
Trerice 988 Series Pressure Regulators are designed for steam service
and recommended for saturated and superheated steam applications.
Valve sizes from 1/2" through 21/2" port are available.
•
Pressure Regulators & Acc.
Trerice 921 Series Pressure Regulators provide a quick response to
large system load changes, while maintaining precise flow regulation.
The 921 Series is capable of both downstream pressure reduction and
back pressure relief. Valve sizes from 1/2" through 6" port are available.
All Trerice Pressure Regulators
should be carefully selected to
meet the demands of the particular
application. The information
contained within this catalog is
offered only as a guide to assist in
making the proper selection.
Selection of the proper pressure
regulator is the sole responsibility
of the user. Improper application
may cause failure, resulting in
possible personal injury or
property damage.
Trerice Pressure
Regulators are NOT
intended for use in
applications where the
media comes in direct
contact with the skin or
body, such as showers,
baths, lavatories or
wash fountains.
Trerice 1002 Series Pressure Regulators are designed for high volume
water service applications. Valve sizes from 1/2" through 21/2" port are
available.
Pressure Range and Set Point
Each Trerice Pressure Regulator is designed to operate efficiently within a
specified operating range. The regulator, when properly specified, will modulate
pressure flow at the set point desired within the selected pressure range. The
set point can be modified using the range adjustment screw provided on the unit.
Pressure Regulator Availability
Size
Series
Body Material
Connection
91500
Bronze
Iron Unions
Cast-Iron
Class 125 Flanged
Bronze
Iron Unions
Cast-Iron
Class 125 Flanged
984
Brass
Threaded
988
Cast-Iron
Threaded
✓
✓
✓
✓
✓
✓
1002
Bronze
Threaded
✓
✓
✓
✓
✓
✓
Cast-Iron
Threaded
921
1/4"
✓
3/8"
✓
1/2"
3/4"
1"
11/4" 11/2"
2" 21/2" 3"
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
4"
✓
✓
✓
✓
✓
✓
5" 6"
✓
✓
✓
✓
Valve
Trerice Two-Piece Pressure Regulators are available with a wide variety of globe
valve designs, materials, connections and sizes.
Style
Trerice Pressure Regulator Valve Bodies are available in single seated and double
seated designs.
•
Single Seated Valves are an excellent choice when a higher degree of shutoff is required. However, this design is unbalanced and limited in the pressure
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12950 W. Eight Mile Road • Oak Park, MI 48237-3288 • 248/399-8000 • FAX: 248/399-7246 • www.trerice.com
What is a Pressure Regulator?
continued
that it will shut off against. The leakage rate is approximately 0.1% of the
maximum capacity.
•
Double Seated Valves are nearly pressure balanced and, therefore, are able
to close the valve plug against higher operating pressures. However, since
temperature fluctuations may cause expansion and contraction across the
seats, tight shut-off is not always possible. The leakage rate is approximately
0.5% of the maximum capacity. Double seated valves have a faster flow
response and greater capacity than single seated valves, and are
recommended when tight shut-off is not required.
Action
The Trerice Pressure
Regulator is a balanced
equilibrium system at the set
point and provides no power
to tightly seat the valve
plug. The valve is not
considered a shut-off valve.
Large pressure surges may
force a single seated valve
plug open. A power driven or
hand actuated valve is
required to ensure tight
shut-off when necessary.
Trerice 921 Series Pressure Regulators can be specified for use in either pressure
reducing or back pressure relief applications. All other Trerice Pressure Regulators
are designed for pressure reducing applications only.
Pressure Regulator Valve Action
Application
Stem Action
Normal (Fail) Position
Pressure Reducing
In-To-Close
Normally Open
Back Pressure Relief
In-To-Open
Normally Closed
Body Material and Connection
Pressure Regulators & Acc.
Trerice Pressure Regulators are available with bronze or cast-iron valve bodies.
Union and flanged connection styles are available.
Trim
Valve trim is composed of the stem and plug assembly, and the seats within the
ports. Trerice single and double seated, bronze valve bodies employ a stainless
steel, tapered plug for enhanced modulation, as well as permanently brazed-in
stainless steel seats for smooth performance throughout the life of the valve. The
valve plug is both top and bottom guided to ensure positive seating alignment.
Packing
Trerice valves feature a self-energizing Teflon V-Ring packing, which reduces
leakage around the valve stem. V-Ring packing is spring loaded to maintain proper
compression and does not require manual adjustment.
Size
The proper sizing of a regulating valve is one of the most important factors in its
selection. A valve that is too small will not be able to provide the desired capacity
during peak load conditions, while a valve that is too large may overshoot the control
point and operate with the valve plug too close to the seat, resulting in undue wear
of the plug and seat. The valve coefficient (Cv) is mathematically determined
through an evaluation of the system service conditions (operating pressures and
flow). From this evaluation, a valve body with the appropriate port size can be
selected. Port sizes from 1/4" through 6" and connection sizes from 1/2" through 6"
are available. Please consult the Valve Selection Section of this catalog.
Valve Coefficient (Cv)
The rated valve coefficient
is used to describe the
relative flow capacity of
the valve based on
standard test conditions.
Please refer to the Valve
Selection Section for
detailed information.
Pipeline Strainer
A Trerice Series 1100 Pipeline Strainer should always be installed
upstream of a Trerice Regulator. This Y-Type strainer employs a stainless
steel screen to remove debris from the line, which will prevent jamming of
the valve and extend its life.
1/1/2001
12950 W. Eight Mile Road • Oak Park, MI 48237-3288 • 248/399-8000 • FAX: 248/399-7246 • www.trerice.com
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