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Water / Clean Fluids
Air Release Valves
Air / Vacuum ValvesCombination Air Valves
Sewage / Wastewater
Air Release Valves (ARV)
Air / Vacuum Valve (AVV)
Single Body Combination
Air Valves (AVC)
Dual Body Combination Air Valves (AVV) Dual Body Combination Air Valve (ASV)
Single Body Combination
Sewage Air Valve (ASC)
Single Body Combination
Air Valves (ASU)
Single Body Combination
Air Valves (ASU)
Air / Vacuum Valve (ASV)
Air Release Valve (ASR)
Body Styles 50A, 200, 200A, 205, 206, 207
Body Styles 140, 140H, 150
Body Styles 1800, 1800K Body Style 401C
Body Styles 143C, 145C,
149C, 150C, 151C
Body Styles 400, 450
Body Style 401
Body Style 440 Body Style SCAVBody Style CAV, SCAV
Theory and Use of Air Valves
Air Release Valves and Air/Vacuum Valves are
essential components to total pipeline design. Without
these essential valves, pipeline capacity will be
reduced 5-10% or more due to air pocket build up in
the pipeline.
This reduced capacity may go unnoticed because air
is an invisible culprit in pipelines. Not only will pockets
of air rob precious line capacity, but entrapped air will
also rob precious electrical energy. The pump will have
to operate at a higher head to overcome the constricted
flow. The elimination of air pockets minimizes the
problem and greatly improves the pipeline efficiency.
2
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Air Release Valves and Air/Vacuum Valves have a fairly
simple construction and are relatively inexpensive.
APCO’s years of experience have proven almost
without exception that the cost of air valves is less than
one percent of the total installed pipeline cost.
Air Release Valves represent low cost insurance for
protection of expensive pipelines. Furthermore, the Air
Release Valves pay for themselves by eliminating air
pockets and maximizing the capacity and operating
efficiency of the pipeline. Additionally, protection against
pipeline damage will also occur because air pockets
are a major factor in surge pressures and water
hammer in a pipeline.
APCO Air Valves
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What are the main types of Air Valves?
There are two main types of air valves:
1.
sizes of 1/2” diameter or smaller)
2.
sizes of 1/2” diameter or larger)
When Air Release Valves and Air/Vacuum Valves are
combined, they become
3. Combination Air Valves (sometimes called Double
APCO Air Release Valve
on long ascending stretch at
1/4 to 1/2 mile intervals
APCO Air Release Valve
on long horizontal and descending
stretch at 1/4 to 1/2 mile intervals
APCO Air/Vacuum Valve on pump discharge before check valve (not necessary for pumps with positive suction head)
APCO Air/Vacuum Valve
at peaks and sharp change in gradient near end of
line where no significant amount of air is anticipated
APCO Combination Air Valve
at peaks and sharp change in gradient due to
possibility of column separation and vacuum
Reservoir
or
Discharge
Air/Vacuum Valve
Air Release Valve
Combination Air Valve
Hydraulic Gradient
Pump
Also install on:
1. Centrifugal pumps
2. Hydropneumatic tanks
3. Enclosed systems
4. Sewage lines
3
Where should air valves be installed on
pipelines?
Air/Vacuum Valves or Combination Air Valves should
be installed on all pipeline high points and changes in
grade.
Air Release Valves or Combination Air Valves should
be installed on those high points where it is possible for
air pockets to accumulate.
Also, Air Release Valves should be installed at intervals
of 1,500 to 2,500 feet on long horizontal runs lacking
clearly defined high points.
Installing manways at intervals in larger size pipelines
provides an excellent point to install Air Release
Valves.
What size air valves are required?
Air Valves can be sized by using the graphs and
formulas in this bulletin or by using the APCO Air Valve
Slide Rule. Contact your local DeZURIK representative
for assistance.
To size air valves for a complete pipeline, your local
DeZURIK representative can create a complete
pipeline profile with recommended valve styles and
orifice sizes using our APSLIDE software program.
Contact your local DeZURIK representative for details.
When calculating where to install APCO air valves, DeZURIK utilizes formulas found in the latest edition of AWWA
Manual of Water Supply Practices M51, titled “Air Release, Air/Vacuum and Combination Air Valves.”
Where to install?
Typical pipeline and position of necessary APCO air valves
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Air Release Valves
What Is An Air Release Valve?
Air Release Valves are hydro-mechanical devices
which automatically vent small pockets of air that
accumulate at high points in a system while the
system is operating and pressurized.
Entrained air will settle out of the liquid being
pumped and collect at high points in the system. If
provisions are not made to remove this air from high
points, pockets of air will collect and grow in size.
Accumulated air pockets in a system can cause
significant problems in pipeline, and Air Release
Valves are devices ideally suited to eliminate those
problems.
Air pocket growth will then gradually reduce the
effective liquid flow area, creating a throttling effect
as would a partially closed valve. Often, the velocity
of the liquid will remove air bubbles if the pipeline
slopes upward. But, if the pipeline is fairly flat, the
ceiling of the pipe is very rough or the pipeline slopes
downward, the velocity may not be sufficient to keep
the air pockets (bubbles) moving.
Air Release Valves must be installed to prevent this
‘throttling’ effect. In extreme cases it is possible for
an enlarging pocket of air collecting at a high point
within a system to create an air block to a degree
where the flow of fluid virtually stops. In this severe
case an entrapped air problem is easily detected and
installation of Air Release Valves at the high points will
remove the restrictive pockets of air to restore system
efficiency.
Another serious consequence is sudden movement
of these air pockets causing rapid velocity changes
of the liquid being pumped. The dynamics involved in
velocity change can be substantial, resulting in high
pressure surges and other destructive phenomena in
the pipelines.
Problems with air entrapped in a system can range
from mild, but costly, to severe and destructive.
Accumulation of air pockets can be easily remedied
by installing Air Release Valves on all high points of a
system.
Air Release Valves for Sewage / Wastewater have an
elongated body to minimize the problem of clogging
by use of a long float stem which creates an air pocket
that prevents sewage from fouling the top mechanism.
The potential for air entrapment with sewage pipelines
is even greater than in water lines because sewage
generates large quantities of gas.
Compound Lever
APCO ARV Air Release Valve
Body Style 200A
Body Style 200
Simple Lever
APCO ARV Air Release Valve
Body Style 50A
Body Style 205
Body Style 207
4
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How Do Air Release Valves Work?
Air Release Valves installed on a high point of the
system will fill with liquid, shut off, and be subjected
to system pressure. During system operation,
small particles of air will separate from the liquid
and enter the valve. Each air particle will displace
an equal amount of the liquid within the valve and
lower the liquid level relative to the float. When the
liquid level lowers, the float will drop. This action
opens the valve orifice and allows the air which has
accumulated in the upper portion of the valve to be
released to atmosphere. As air is released, the liquid
level within the valve rises again, lifting the float and
closing the valve orifice. This cycle repeats itself as
often as air accumulates in the valve.
Air Release Valves use of a leverage mechanism to
open and release accumulated air under pressure.
When the float is no longer buoyant, this mechanism
(plus the weight of the float) produces a greater
force to open the valve than to hold the valve
closed.
Accordingly, the higher the system pressure the
smaller the orifice diameter must be to allow
the valve to open and release accumulated air.
Conversely, with the same valve and a lower system
pressure, a larger diameter orifice can be used to
release accumulated air.
Air Release Valves are not normally recommended
for vacuum protection nor to vent large volumes of
air when filling large diameter pipelines because
they have small orifices, usually less than 1/2”
diameter. Air/Vacuum Valves have much larger
orifices for this purpose. However, Air Release
Valves will permit small quantities of air to re-enter
under negative conditions. To prevent air re-entry,
an Air Release Valve with a vacuum check may be
specified.
APCO ASR Sewage
Air Release Valve
Body Style 400, 450
5
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Sizing Air Release Valves
Air Release Valves discharge air (which has
accumulated inside the valve) from high point in
the pipeline. Generally, Air Release Valves are not
constantly discharging air during system operation, but
only discharge intermittently as air accumulates.
Air entrapped in pipelines is an invisible culprit and it
can be difficult to quantitatively measure the precise
amount of entrapped air in a flooded transmission
pipeline. Variables such as the source of media,
pressure differential across the pump, operating
pressure, and pressure/ temperature fluctuations
along the transmission line will affect the amount of
air released from the media. However, the volume of
liberated air (from the media) which accumulates and
must be vented from each high point can be calculated
as follows:
Air Valve Sizing
1. Use 2% of the media volume divided by the
number of high points as the minimum amount
of entrapped air.
2. Consider this volume as the basis for the amount
of air to be discharged from each high point.
Amount of air to be discharged CFM = Flow
Capacity in GPM x 2%
or Flow Capacity in GPM
1500
1000
500
200
150
100
50
20
10
5
2
1
Venting Capacity in Cubic Feet of Free Air Per Minute
Venting Capacity Graph for Air Release Valves
Orifice Sizes
Pressure Differential Across Valve in psi
6
3. Upon determining the operating pressure of the
system, refer to the Venting Capacity Graph for
Example:
1.
operating at 150 psi.
Amount of air to be discharged = = 50
CFM
2. Using the Venting Capacity Graph for Air Release
Valves
curve.
3.
appropriate inlet size.
Sizing an Air Release Valve when a Specic venting
capacity is required
1. On the Venting Capacity Graph for Air Release
and the venting capacity required on the X axis.
2.
of pressure and capacity lines on graph.
3.
Note: If the intersection of the Venting Capacity (CFM) and Operating Pressure (psi) lies between two orifice
curves, use the larger orifice.
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Valve
Type
Body
Style
End
Connection
Order Code
Body
Material
Valve
Size
Orifice
Order
Code
Orifice
Diameter
Valve
Minimum
Rated
Pressure
(psi)
Valve
Maximum
Rated
Pressure
(psi)
Venting
Capacity
(CFFAM)
ARV
50A T1 DI .5-1"
R332 3/32"
R116 1/16" 11 300 12
200A
T1 & F1N DI 1-2"
L516 5/16" 3 15 25
R516 5/16" 11 50 65
R14 1/4" 11 65
R316 3/16" 11 150 60
T1 DI 1-2"
R532 5/32" 11 300
M332 3/32" 11 600 55
F1N DI* 1-2"
R532 5/32" 11 250* 65
M332 3/32" 11 250* 25
200
T1, F1N, & F2N DI 2-3"
L12 1/2" 3 15 60
R12 1/2" 11 225
51 150 250
T1 DI 2-3" 51 300 150
F1N DI* 2-3" 51 250* 130
F2N DI 2-3" 51 300 160
205 T1 DI 2"
H12 1/2" 50 100 300
50 150 250
50 500 250
50 125
206
T1
CS 2"
H332 3/32" 50 1500 150
F4N H332 3/32" 50
F6N H332 3/32" 50 140
F1 DI* 6"
L1 1" 3 15 235
R1 1" 11 150
3/4" 11 250* 1250
ASR
400
T1 & F1N DI 2-4"
L516 5/16" 3 15 25
R516 5/16" 11 50 65
R14 1/4" 11 65
R316 3/16" 11 150 60
T1 DI 2-4" R532 5/32" 11 300
F1N DI* 2-4" R532 5/32" 11 250* 65
450
T1 & F1N DI 2-4"
L12 1/2" 3 15 60
R12 1/2" 11 225
H12 1/2" 51 150 450
T1 DI 2-4" 300 550
F1N DI* 2-4" 250* 450
ASU
CAV
T1 S2 1-4" H516 5/16" - 300 300
F1 S2* 2-4" H516 5/16" -
SCAV
T1 S2 1-4" R516 5/16" - 150
F1 S2* 1-6" R516 5/16" -
Table of Orifice Sizes for Air Release Valves
Pressure Ratings are at ambient temperature. Limiting factor for Working Pressure is the lowest pressure rating of the end
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Air/Vacuum Valves
What Are Air/Vacuum Valves?
Air/Vacuum Valves allow large volumes of air to be exhausted
from or admitted into a system as it is filled or drained. Air/
Vacuum Valves are float operated and have a large discharge
orifice, equal in size to the valve inlet.
Prior to filling, a pipeline is filled with air. This air must be
exhausted in a smooth uniform manner to prevent pressure
surges and other destructive phenomenon from occurring in
the pipeline. Conversely, air must also be allowed to re-enter
the pipeline in response to a negative pressure in order to
prevent a potentially destructive vacuum from forming. Even
when vacuum protection is not a primary concern, air re-entry
is still essential to efficiently drain the pipeline.
At locations where column separation is anticipated an Air/
Vacuum Valve will allow air to enter, preventing a destructive
vacuum from forming which is as damaging as pressure
surges.
Air/Vacuum Valve Operation
As the pipeline is filled, air is exhausted to atmosphere
through an Air/Vacuum Valve mounted on each high point.
As air is exhausted, water will enter the valve and lift the
float to close the valve orifice. The rate of air exhausted is a
function of pressure differential, which develops across the
valve discharge orifice. This pressure differential develops
as water filling the pipeline compresses the air sufficiently to
give it an escape velocity equal to that of the incoming fluid.
Since the size of the valve controls the pressure differential
at which air is exhausted, valve size selection is an important
consideration.
During system operation, the internal pressure of the pipeline
can approach a negative value due to events such as column
separation, draining of the pipeline, power outage or pipeline
break. This will cause the float to immediately drop away from
the orifice and allow air to re-enter the pipeline. Air re-entry
during water column separation will prevent a vacuum and
protect the pipeline from collapse. The Air/Vacuum Valve,
having opened to admit air into the pipeline in response to
a negative pressure, is now ready to exhaust air again. This
cycle will repeat as often as necessary.
During system operation and while under pressure, small
amounts of air will enter the Air/Vacuum Valve from the
pipeline and displace the fluid. Eventually, the entire Air/
Vacuum Valve may fill with air, but it will not open because the
system pressure continues to hold the float closed against the
valve seat. An Air/Vacuum Valve’s purpose is only to exhaust
air during pipeline fill and to admit air during pipeline drain.
An Air Release Valve is required to release accumulated air
pockets during system operation.
APCO AVV
Air/Vacuum Valve
Body Style 150, 4-18”
APCO AVV
Air/Vacuum Valve
Body Style 140, .5-3”
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Characteristics of Air Flow Through an
Air/Vacuum Valve Orice
The linear velocity of air discharged through the
orifice of an Air/Vacuum Valve increases as pressure
differential across the orifice increases, until reaching
a maximum velocity of approximately 300 feet per
and remains a constant thereafter, regardless of further
increase in the pressure.
Unlike liquids, the volume of air that fills one cubic foot
at atmospheric pressure will occupy a progressively
lesser volume as its pressure increases.
The amount of air actually expelled through the orifice
continues to increase indefinitely as the pressure
increases. While there is no further increase in the
escaping at this velocity becomes progressively denser
and represents a greater amount when expressed
in cubic feet at atmosphere. To accommodate this
condition, flow of air is always referred to in Cubic Feet
of Free Air per Minute (CFFAM) even though the air
under consideration is usually at some other pressure
than atmosphere.
APCO ASV
Sewage Air/Vacuum Valve
Body Style 401
9
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Sizing Air/Vacuum Valves
APCO Air/Vacuum Valves open whenever the internal
pressure of the pipeline approaches a negative value,
allowing the water level in the valve to lower and the
float to drop from the seat. The function is to vent large
volumes of air from pipelines when they are initially
filled and to allow air to re-enter the lines to break a
vacuum.
On a typical pipeline profile, the gradients indicated
can be used for pipeline slopes for calculating the
flow down the pipeline. A minimum valve size is
established by finding the size for filling, which is
usually less than the drainage flow. A 2 psi pressure
the drainage flow. Above 2 psi, the air flow out across
the valve orifice becomes so great, it may cause two
problems: First, the valve may close prematurely due
to turbulence, trapping an air pocket in the system.
Secondly, when the valve closes, the abrupt cessation
of flow may create substantial pressure rise and slam,
which may damage the air valve or pipeline. The 5 psi
differential for inflowing air represents a safe average
for protecting the pipeline and gasketed joints from
damage due to vacuum.
Air/Vacuum Valve Sizing
1. Calculate necessary valves independently for
each high point line.
2. Consider the more severe of the two gradients
adjacent to each high point.
3.
per second which can occur in this gradient for
If the line is being lled by pump:
CFS = GPM of pump
If the line is being drained by gravity:
CFS
5
Where S = Slope (in feet per foot of length)
D = Diameter of pipe (inches)
4. The valve to be installed at this high point must
release or re-enter an amount of air in cfs equal
CFS
immediately adjacent to this now determined high
point.
10
5. To economize on the size of valves selected, the
in CFS already determined.
6.
pressure, if there is a risk of line collapse from
vacuum. This condition is usually only present
in thin-walled steel lines above 24". To calculate
collapsing pressure for thin-walled, cylindrical
pipe.
P = 12500000 T
3
Where P = Collapsing pressure (psi)
T = Thickness of pipe (inches)
D = diameter of pipe (inches)
Includes Safety Factor of 4
Inow
whichever is lower. Follow the line for this
size that will protect the line from collapse and
water column separation due to vacuum.
Outow
vent all air from the line before valve closure. This
ensures maximum performance from the line.
9. Compare the valve sizes determined in steps
protection of the system.
10. These valves should be installed on the high point
11. The same procedure should be followed for each
individual high point.
12.
if the high points are separated by long stretches
of uniform gradient, it is recommended that the
proper valves be selected as explained above and
duplicate installations be made at regular intervals
449
D
( )
DeZURIK.com
12346810121416182024
1
⁄
2
Valve Size
1
2
3
4
5
6
Vacuum across valve in psi
Inflow
Standard Cubic feet of free air per second (SCFS)
Valve Size
6
5
4
3
2
1
Press. diff. across valve in psi
.2 .3 .4 .6 .8 1 2 3 4 5 7 10 20 30 50 100 200 500 1000 2000
Outflow
1
⁄
2
Standard Cubic feet of free air per second (SCFS)
11
Performance Graphs for Air/Vacuum Valves
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Combination Air Valves
What Are Combination Air Valves?
Combination Air Valves have operating features of both Air
Release Valves and Air/Vacuum Valves. Combination Air Valves
are installed on all high points of a system where it has been
determined Air/Vacuum and Air Release Valves are needed to
vent and protect a pipeline. Generally, it is sound engineering
practice to use Combination Air Valves instead of single purpose
Air/Vacuum Valves.
Combination Air Valves are available in two body styles:
1. Single Body Combination Air Valves
The Single Body Combination Air Valve is used where
compactness is preferred and/or where risk of tampering
exists due to accessibility of the installation.
2. Dual Body Combination Air Valves
Dual Body Combination Air Valves are an Air/Vacuum Valve
piped with a shut-off valve to an Air Release Valve. Dual
Body Combination Air Valves can have greater versatility
than the single body style because a variety of Air Release
Valves with a wide range of orifices and higher operating
pressures can be used.
For pipeline economy and operating efficiency, pipelines should
be laid to grade where possible, rather than merely following the
natural terrain. The result will be smoother less turbulent flows of
liquid, fewer high points where air will collect, so fewer air valves
are needed.
How Do Combination Air Valves Work?
Combination Air Valves exhaust large volumes of air as the
system is filled and prevent the accumulation of air at high points
within a system by releasing accumulated pockets of air while the
system is operational and under pressure. Combination Air Valves
prevent potentially destructive vacuums from forming during
power outages, water column separation or sudden rupture of the
pipeline. Additionally, these valves allow the system to be easily
drained because air will re-enter, as needed.
Potentially damaging vacuum conditions and pressure surges
induced by air can be avoided and maximum pipeline efficiencies
attained through proper understanding and application of air
valves.
APCO AVC Single Body
Combination Air Valve
APCO ASU Single Body
Combination Air Valve
Body Style CAV, SCAV
APCO AVV Dual Body
Combination Air Valve
Body Style 1800, 1800K
APCO ASV Dual Body
Sewage Combination Air Valve
Body Style 401C
12
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Options
Slow Closing Valves
What is a Slow Closing Air Valve?
The APCO Slow Closing Air Valve (CSV) is a standard
Air/Vacuum Valve mounted on top of a Surge Check
Unit. The Slow Closing Air Valve is designed to
eliminate critical shock conditions on installations where
operating conditions cause a regular air valve to slam
shut.
How Does a Slow Closing Valve Work?
The Air/Vacuum Valve operates in the normal fashion
allowing air to escape freely. The Surge Check Unit
operates on the interphase between the kinetic energy
in the relative velocity flow of air and water.
Air passes through unrestricted but when water rushes
into the Surge Check Unit, the disc closes and reduces
the rate of water flow into the air valve by means of
throttling holes in the disc. This ensures normal gentle
closing of the Air/Vacuum Valve regardless of the initial
velocity flow involved. This also minimizes pressure
surges when the valve closes.
As soon as the air valve
is closed, the pressure
on both sides of the
Surge Check Unit disc
equalizes and the disc
automatically returns to
its open position. This
means the air valve surge
check does not need an
incipient vacuum to open,
but can open at any time
the water level drops and
line pressure approaches
atmospheric level. This
immediately allows the
full re-entry flow of air
into the pipe line.
Refer to bulletin 613 for details.
13
Vacuum Relief/Air Inlet Valves
What Are Vacuum Relief/Air Inlet
Valves?
Vacuum Relief/Air Inlet Valves (AVR) are large orifice
one-way valves. They permit air to enter the pipeline or
system (to break the vacuum), but no air escapes when
the system pressure returns to positive.
Vacuum Relief/Air inlet Valves are normally closed
spring-loaded valves that respond to a vacuum in the
pipeline. The Vacuum
Relief/Air Inlet Valve
is designed to open
with a minimal 1/4 psi
pressure differential
across the orifice.
Higher or lower
settings are available.
Vacuum Relief/Air inlet
Valves are available
in combination with
APCO Air Release
Valves to permit
full flow air into the
pipeline and slow air
out of the pipeline
through the Air
Release Valve orifice.
Refer to bulletin 1500 for details.
APCO AVR
Vacuum Relief/ Air Inlet valves
Slow Closing Air/Vacuum
Valve, AVV Body Style 150
with CSV Surge Check Valve
Air Valves for Vertical Turbine Pumps are essential to
prevent large volumes of air from entering the water
system each time the pump is started and to break
a vacuum when the
pump stops. Air Valves
for Vertical Turbine
Pumps are basically
Air/Vacuum Valves
with additional options
and accessories such
as an internal Water
Diffuser (WD) or an
external Double Acting
Throttling Device (DAT)
or inlet water Surge
Check Valve (CSV).
DeZURIK, Inc. reserves the right to incorporate our latest design and material changes without notice or obligation.
Design features, materials of construction and dimensional data, as described in this bulletin, are provided for your information only
and should not be relied upon unless confirmed in writing by DeZURIK, Inc. Certified drawings are available upon request.
For information about our worldwide locations, approvals, certifications and local representative:
Web Site: DeZURIK.com E-Mail: [email protected]
Sales and Service
These options and accessories are essential to suit
these valves for use on Vertical Turbine deep well
pumps. Without these features, a basic Air/Vacuum
Valve will most likely spill substantial amounts of
water before
shutting off,
or it may not
shut off at all.
These features
will prevent
premature closure
due to the air
in the suction
column being
saturated with
moisture.
Refer to bulletin
AVV Air/Vacuum Valve with
Surge Check (CSV)
AVV Air/Vacuum Valve with
Double Acting Throttling
Device (DAT)
Air Valves for Vertical Turbine Pumps
