AIR CONTROL IN

WATER SYSTEMS
A GUIDE FOR SYSTEM DESIGNERS
This guide offers tools for planning air control,
selection and specifications of air valves.
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TABLE OF CONTENT
Company Profile 3

Chapter 1 Principles of Air Control in pressurized water systems 7

Chapter 2 Air Valves benefits and Air Valves types 9

Chapter 3 Air Valves principles of operation 11

Chapter 4 WaterWorks & Buildings typical applications 13

Chapter 5 Air Valves locations 14

Chapter 6 Air Valve sizing principles 19

Chapter 7 BERMAD AIR - Sizing & positioning software 20

Chapter 8 Preliminary sizing graphs 24

Chapter 9 Surge analysis 26

Chapter 10 Air Valves specifications 28

Chapter 11 Installation considerations 29

Chapter 12 BERMAD air flow test bench for air valves 31

Chapter 13 BERMAD Air Valves – Why they are better for your system 32

Chapter 14 BERMAD Air Valves certifications 33

Chapter 15 BERMAD Air Valves product matrix 34

Bermad Disclaimer 35

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Irrigation Fire Protection Buildings & Waterworks Mining

Construction

Company Profile Innovation

BERMAD is a leading, privately-owned global company that designs,

develops and manufactures tailor-made water & flow management
Integrity
solutions that include state-of-the-art hydraulic control valves, air valves and
advanced metering solutions.

Founded in 1965, we have spent over 50 years interacting with the

world’s major end users, and accumulating knowledge and experience in Commitment
multiple markets and industries. Today, we are recognized as a pioneer
and established world-leading provider of water & flow management
solutions that give our customers the unprecedented operational efficiency,
and superior quality, durability and performance they need to meet the
Quality
demanding challenges of the 21st century.

Customized for the unique needs of multiple sectors Professionalism

Incorporating advanced water & flow management capabilities, our

best-of-breed solutions have been carefully customized to meet the unique needs of
multiple sectors and industries.

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Irrigation
Our vision is to provide integrated irrigation management
solutions. To this end, we continuously develop our team
capabilities to acquire the deepest practical knowledge. We
strive to be a “one-stop shop” for our customers by designing,
manufacturing and providing support for the widest range of
innovative water flow management products that are
integrated into efficient and cost-effective solutions for the full
range of agricultural irrigation needs.

Fire Protection
Our globally-proven fire protection solutions incorporate unique,
patented technologies for fail-safe, minimum flow obstruction and
high-resistance to water hammer and surge. Providing the
greatest reliability over the longest service life, these high-quality
solutions can be found throughout the world as vital components
of fire protection systems, including high-hazard areas and
installations that require unique solutions – helping to save lives
and prevent property damage in fire events. BERMAD fire
protection valves meet the most demanding industry standards.

Buildings & Construction

The Buildings & Construction industry has unique requirements,
which, together with their fire protection requirements, must be
taken into account when designing and installing their water
supply and distribution systems. For this reason, our water &
control management solutions for the Building & Construction
industry are designed and manufactured with careful
consideration for important issues such as constant water
supply, noise and maintenance considerations, sanitary and
safety, integration and control and high water consumption.

Waterworks
As pioneers in water supply protection and efficiency, our
proven water & control management solutions include state-of-
the-art hydraulic control valves, air valves and advanced water
meters. Whether for bulk water supply systems, water
distribution network grids, or waste water pumping stations and
delivery lines, we offer robust and reliable solutions that help
optimize water usage, maximize energy efficiency, reduce costs,
protect water supply and distribution systems, and keep water
system downtime to a minimum.

Mining
Our comprehensive range of custom-made, high-performance
and proven control valves, air valves and surge protection
devices are widely deployed in the mining industry worldwide,
providing solutions for the toughest flow control applications in
copper, gold, iron, coal and other precious metal mines.

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BERMAD WORLDWIDE

USA UK India

Italy China

Israel

France

Australia
Mexico Spain

Brazil Singapore

Operating globally for your peace of mind

Our extensive global network works together to offer our customers exceptional service and
peace of mind. With 12 globally-dispersed subsidiaries and distributors or a direct presence in over
85 countries, we have built a reputation of top-quality sales and after-sales service supported by
highly-trained and dedicated professionals.

This enables us to make a significant contribution in the world arena, and to take part in multiple
large-scale international projects. From the Channel Tunnel to the 3 Gorges Dam in China, and
from the irrigation fields of Asia and South America to the oil fields of the North Sea and the
Persian Gulf, governments and private sector partners around the world rely on our solutions for
all their water & flow management needs.

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Water
Control
Solutions

Dedicated to precision engineering and ongoing support

With an understanding that comprehensive water flow management solutions are only as effective as
their smallest component, we design, develop and manufacture all hydraulic control valves, air valves
and advanced metering solutions in-house according to the most stringent quality procedures.

This dedication to innovation, precision, quality and reliability enables us to adapt and customize our
solutions to meet almost any customer need; to constantly integrate the latest and most reliable
manufacturing techniques into our processes; and to provide every customer with excellent
comprehensive commercial and technical support before, during and after installation.

Helping to manage the world’s most precious resource

At BERMAD, we understand that the efficient and smart management of our planet’s most precious
resource is as vital as the resource itself.

This underpins our commitment to designing, manufacturing and supplying water & flow management
solutions that help reap the full benefits of every single drop of water.

Our dedication to our customers is matched by our commitment to the environment. In addition to
offering comprehensive solutions that maximize the usage efficiency of water and other resources, we
are constantly searching for new and better manufacturing materials and methods to ensure
sustainability. As a result, our products comply with the most stringent international environmental
standards and certifications.

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Chapter 1 - Principles of Air Control in pressurized water systems

Introduction
The presence of uncontrolled quantities of air in water systems can seriously affect their performance, causing inefficient
filling and draining procedures and flow reduction, while increasing energy costs. It also disrupts the operation of some
of the system’s components. On the other hand, air is essential in dealing with vacuum conditions and pressure surges.
Effective control of air in a water network is based on evaluating the required air volume during various modes of
operation, and according to the required volume, the proper positioning and sizing of the air valves.
Air control in pressurized water systems is critical for increasing efficiency during filling, draining and pressurized
operation, as well as to protect them from vacuum conditions and pressure surge.

Sources of air in water systems

There are various sources to the presence of air in water systems:
n At the starting point, when the system is empty, it is being filled with air.
n All liquids contain dissolved air. The volume of the dissolved air depends on pressure and temperature; it is around
2% at atmospheric pressure and a temperature of 25°C, 77°F.
In pressurized systems, the pressure varies along the pipeline, according to the Hydraulic Grade Line (HGL) and pipeline
profile. At points where the pressure drops, the dissolved air is transformed into air bubbles, which will accumulate to
air pockets in the system.

Picture 1.1 – Creation of air bubbles Picture 1.2 - Entrapped air pockets increase head losses

n Turbulent flow will create a mixture of air and water downstream of the reservoirs and further into the line.
n Centrifugal pumps promote vortex formation allowing large quantities of air into the system.
n In municipal sewage systems, air bubbles are also generated by microbiological activity.
Significance of air in water systems
The significance of air in water systems is different in each of their various operating modes
n Pipeline filling:
To allow efficient filling, air has to be relieved or evacuated. In case the air is not being effectively relieved,
the pipeline filling time will increase significantly. A large volume of air, which was not relieved during pipeline
filling, might lead to pressure surges.
n Pressurized operation (Steady State):
Air bubbles will accumulate at the higher points in the system, and gradually reduce the effective cross section of
the pipe. The result will be reduction in flow and increased energy costs (to maintain the design flow).
In extreme cases, the pump will be unable to supply the required extra head needed to overcome the air pockets
and flow in the system might completely stop. Click to watch Animation.

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Picture 1.3 - Air bubbles create entrapped air pockets

In addition, air disturbs the operation components such as pumps, regulating valves and filters. Mechanical water
meters, whose readings are based on liquid velocity, will provide inaccurate readings due to the presence of air in the
meter. Also the presence of air in high volumes in the system will contribute to enhance corrosion in metal pipelines.
n Pipeline draining:
During system draining, whether due to burst or maintenance, negative pressures (Vacuum Conditions) will be
created. Negative pressures may damage different components and under severe conditions can lead to pipeline
collapse. Allowing air intake will eliminate negative pressures and protect the system. Click to watch Animation..

Picture 1.4 - Negative pressure during pipeline draining

In addition, since negative pressure creates suction into the system from the atmosphere.
In potable water systems, where devices are installed in underground chambers, entrance of contaminated water
can be a major problem.
In drip irrigation systems, dirt and soil may enter the system and clog the drippers’ nozzles.
n Pressure surge (Water Hammer):
Pressure surges may be a result of pump trip, fast valve closure and more. It is likely, that in the same magnitude
the pressure rises, it will also drop. In some cases, pressure becomes negative (Vacuum Conditions), and in worst
cases water column separation may occur, along with cavity formation.
Without a proper control of the surge pressure, the system may suffer significant damages. Neutralizing the
Vacuum Conditions will require air intake at critical points, based on Surge Analysis. Click to watch Animation.

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Chapter 2 – Air Valves benefits and Air Valves types

Benefits of Using Air Valves
Stage Air Valve’s Function Benefits
Increase system efficiency and shorten filling time
Pipeline filling Air relief
Click to watch Animation.
Protection from vacuum conditions and pipe collapse
Pipeline draining or burst Air intake
Click to watch Animation.
Air release Increase system efficiency, save energy and pumping cost
(entrapped air pockets)
Pressurized operation Prevents false readings by water meters
Air release
(air bubbles) Prevents malfunction of regulation devices and filters
Protection from vacuum conditions
Water hammer (Surge pressure) Air intake, air relief Controlled & safe air relief
Click to watch Animation.

Picture 2.1 - Picture 2.2 - Picture 2.3 -

Air intake Releasing entrapped air pockets Air relief

Types of Air Valves

There are 3 basic types of Air Valves:
n Automatic Air Valve (Air Release):
The valve releases entrapped air pockets during pressurized operation. It has one single small orifice, called the
Automatic Orifice, in diameters of 0.04 - 0.2 inch; 1 - 5 mm.
n Kinetic (Air / Vacuum) Air Valve:
The valve evacuates air during pipeline filling and enables air intake in the event of system draining or vacuum
conditions. It has one single large orifice, called the Kinetic Orifice, in diameters of 1 - 10 inch; 25 - 250 mm.
A Kinetic Air Valve, which is restricted only to air intake, is also known as Vacuum Breaker.
n Combination Air Valve:
The valve combines the function of Automatic and Kinetic Air Valves. It evacuates air during pipeline filling, allows
efficient release of air pockets from pressurized pipes, and enables air intake in the event of network draining or
vacuum conditions. It has two orifices – Automatic and Kinetic. Click to watch Animation.
Air Valves are also classified by the type of water:
n Air valves for Clean Water:
To be used with drinking water, irrigation water, reused or recycled water.
n Air valves for Non Clean Water:
To be used with unclean waters, for example, municipal sewage, industrial and mining systems. Their function
is the same as that of the Clean Water Air Valves; however, the main difference lies in their elongated body and
internal parts designed to keep the water apart from the valve mechanism.

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Additional Features for Air Valves

n Surge Protection - SP (Non-slam):
Designed for partially close the kinetic orifice during air relief. It prevents the slam/shock resulting from a rapid
closure of the kinetic orifice during pipeline filling or water column separation. The Surge Protection feature
ensures smoother operation and prevents damage to the air valve or system. Click to watch Animation.
n Assisted Closing - AC:
This feature is similar to SP, but in this case the SP disc is held upwards using a spring. It means that, regardless of
inline pressure, outflow is only through the SP disc (switching value = 0).
n Inflow Prevention - IP:
Prevents intake of atmospheric air in cases where this could lead to damaged pumps, required re-priming, or
disruption of siphons. It also prevents intake of flood or polluted water into drinking water networks.

Picture 2.4 - Combination Air Picture 2.5 - Combination Air Picture 2.6 - Combination Air
valves with an addition feature of valves with an addition feature valves with an addition feature of
Surge Protection (SP) disc. of Assisted Closing (AC) Surge Inflow Prevention (IP).
Protection disc.

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Chapter 3 – Air Valves principles of operation

Pipeline Filling
During the filling process of a pipeline, a high volume of
air is being forced out through the kinetic orifice of the
air valve. Once water enters the valve chamber, the float
buoys upwards, causing the kinetic orifice to close.

Picture 3.1 - C70, Air relief during pipeline filling

Click to watch C70 Principle of Operation Animation

Pressurized Operation (Steady State)

During pressurized operation of the pipeline, air bubbles
accumulate in the upper part of the air valve chamber,
causing the float to gravitate downwards.
This in turn causes the automatic orifice to open, releasing
the accumulated air. As the air has been discharged, the
water level and float will rise, causing the automatic orifice
to close.

Picture 3.2 – C50, Automatic Air Release

Click to watch C50 Principle of Operation Animation

In BERMAD’s C70 and C75 models, the automatic orifice

opens in a two-step action, forming an air gap between
the water level and the automatic orifice and only then
releasing the accumulated air, while minimizing the spray
effect. As the air has been discharged, the water level and
float will rise, causing the automatic orifice to close.

Picture 3.3 -
C70, Automatic Air Release with a two-step action
Click to watch C70 Principle of Operation Animation

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Vacuum conditions
(Burst, Drainage, Negative pressure surge)
Whenever the pipeline is being drained, or following a burst,
a negative pressure (Vacuum) will be created. The kinetic
orifice will stay open to draw large volume of atmospheric
air into the pipeline, thus preventing vacuum formation.

Picture 3.4 C30, Air intake during vacuum conditions

Click to watch C30 Principle of Operation Animation

Surge Protection Feature (Non-Slam)

In case of the pipeline filling at high velocity, or in the
event of a pressure surge, the Surge Protection (SP) disc
rises (at an air relief pressure of around 7 psi; 0.05 bar)
partially closing the valve’s orifice. The approaching water
decelerates due to the resistance of the rising air pressure
in the valve and pipe, e.g prevent air valve slamming.
BERMAD’s C70 and C75 models have also an Assisted Closing
(AC) feature. It is similar to the Surge Protection (SP) feature,
but the disc is pulled up to the kinetic Orifice by a spring.
This means the kinetic orifice is always partially closed. Picture 3.5 – C70, Air relief with Surge Protection (SP)
Click to watch C70 Principle of Operation Animation

BERMAD’s C10, C30 and C50 models have a Surge Protection

mechanism, based on a flexible seal that partially closes
the valve outlet with the increase of air relief.

Picture 3.6 – C50, Air relief with Surge Protection (SP)

based on a Seal.

Inflow prevention feature

The inflow prevention mechanism is a Normally Closed
check disc mounted on the top of the valve kinetic orifice
(BERMAD’s C70, C75 models) or threaded to the valve outlet
(BERMAD’s C10, C30 & C50 models) to prevent atmospheric
air from entering the valve.
Picture 3.7 C70 with Inflow Picture 3.8 C30 with Inflow
Prevention feature Prevention feature

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Chapter 4 – Typical Applications

Water Works

Picture 4.1 - Pumping station Picture 4.2 - Pumping station

Picture 4.3 - Full redundancy Pressure Reducing system Picture 4.4 - Main reservoir

Picture 4.5 - Elevated reservoir Picture 4.6 - Municipal sewage system

See additional videos and information for Air Valve's applicaitons in Bermad City at https://go.bermad.com/citycenter-0

Buildings & Constructions

Picture 4.7 - On floor pressure reducing system Picture 4.8 – On Floor pressure reducing station
See additional videos and information for Air Valve’s applications in Bermad City Center at https://go.bermad.com/citycenter

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Chapter 5 - Air Valves locations

Proper air control is a vital factor in water systems design. Appropriate location and sizing of Air Valves are critical to
avoid water hammer and head loss, while achieving optimal efficiency and extending the system lifespan.
The following are guidelines for the location of Air Valves.

Along the pipeline

1. High points  Combination Air Valve
At high points, a Combination Air Valve is required for:
n Air relief during pipeline filling
n Air intake to prevent vacuum conditions in case of the pipeline being drained
n Air release of entrapped air pockets during pressurized operation.

Picture 5.1 – High point

2. High points where pressure is low  Combination Air Valves + Surge Protection Feature
Same consideration like with any other high point, but with the addition of a Surge Protection (SP) feature to prevent
air valve slamming during pipeline filling or any other transient scenario that might lead to water column separation.

3. Pipeline downslope increasing or upslope decreasing  Combination Air Valve

When the pipeline downslope is increasing or the upslope is decreasing, a Combination Air Valve is required to:
n Release entrapped air pockets during pressurized operation (air bubbles will be created due to pressure loss).
n Allow air into the pipeline to prevent water column separation during any transient scenario.

Picture 5.2 - Increasing downslope Picture 5.3 - Decreasing upslope

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4. Along the pipeline  Combination or Automatic Air Valve

Along horizontal sections or long ascents of the pipeline, Combination Air Valves will be required for air relief, air intake
and release of entrapped air pockets during pressurized operation.
Along pipeline descents, Automatic Air Valves will be required for release of entrapped air pockets during steady state
conditions.
Distance between Air Valves should be 400 - 800 meters; 0.25 – 0.5 miles.

Picture 5.4 - Along horizontal pipelines

In the system
5. Pumping stations  Combination Air Valve + Surge Protection Feature
At the pump discharge pipe, downstream from the check valve, a Combination Air Valve with the addition of a Surge
Protection (SP) feature will be required. In order to protect against water column separation and vacuum conditions,
by ensuring controlled & safe air relief during pump start-up, shut-off or power failure.

Picture 5.5 – Pumping stations, downstream the check valve

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6. Deep well pumps  Combination Air Valve + Surge Protection Feature

At the pump suction pipe, between the pump and the check valve, a Combination Air Valve with the addition of a
Surge Protection (SP) feature will be required to prevent vacuum conditions during pump shut-off and ensure a safe
and controlled venting of the suction pipe at pump start-up.

Picture 5.6 – Deep Well Pump, between the pump and the check valve

7. Crossing a road, river or canal  Automatic Air Valve

Crossing a road, river or canal is carried out through abrupt changes in the slopes. Automatic Air Valves will be required
to release air bubbles, thus preventing the accumulation of air pockets at these points.

Picture 5.7 - Crossing a road, river or canal

8. Water meters  Automatic Air Valve

Upstream of water meters an Automatic Air Valve will be required to release air bubbles, which might bias the flow
measurements.
Straightening distance according to manufacturer requirements

Picture 5.8 – Upstream of mechanical water meters

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9. Pressure/Flow regulating valve  Automatic Air valves

Pressure reducing creates additional air bubbles downstream of regulating devices such as hydraulic control valves,
etc. Automatic Air Valves will be required to release air bubbles.
In addition, the arrival of additional air bubbles might interfere with the operation of regulating devices, so installing
Automatic Air Valves also at the upstream should be considered.

Picture 5.9 – Upstream and Downstream of regulating devices

10. Isolation valve  Combination or Kinetic Air Valve

Combination or Kinetic Air Valves will be required to prevent vacuum conditions and pipeline failure while isolation
valves installed upslope, downslope or above ground are closing.
On downslope, the Air Valve will be installed downstream of the isolation/control valve.
On upslope, the air valve will be installed upstream of the isolation/control valve.
On above ground installations, Air Valves will be required both upstream and downstream.

Picture 5.10 – Isolation valve in up / down slope lines Picture 5.11 – Isolation valve above ground

11. Orifice or Restriction points  Combination or Automatic Air Valve

Combination or Automatic Air Valves will be required downstream of an orifice/restriction to reduce cavitation, noise
and vibration.

Picture 5.12 - Orifice or restriction

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Summary

Picture 5.13 - Locations along the pipeline

Legend
n Pumping station - Point 1: Combination with SP
n High point where pressure is low - Point 3: Combination with SP
n Decrease upslope - Point 6: Combination
n Long sections - Points 2, 4, 5, 7, 8: Combination or Automatic

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Chapter 6 - Air Valve sizing principles

In order to optimize air control, it is important to select the proper size of the Kinetic Orifice and the Automatic Orifice
for each and every Air Valve, in each specific location along the pipeline and in the system.

1) Sizing the Kinetic Orifice for Pipeline Filling (Air Relief)

The first goal is to allow an efficient pipeline filling by ensuring sufficient air relief from the pipeline. The volume of air
that all kinetic orifices along the pipeline have to relieve will be calculated according to the following formula:

n Qair - Required air flow (m3/hr)

n A - Pipeline cross section flow area (m2)
n V – Filling flow rate (m/s)

The selected Air Valve should discharge the required air capacity at inline pressure of 3 psi; 0.2 bar.
To ensure safe pipeline filling, it is recommended not to exceed a filling velocity of 1 feet/sec; 0.3 meter/sec.
For a higher or unknown filling rate, an Air Valve with the addition of a Surge Protection device is highly recommended.

2) Sizing the Kinetic Orifice for Burst or Draining (Air Intake)

The next essential goal is to prevent vacuum conditions along the pipeline, when the system is being drained, whether
due to burst or for maintenance purposes.

2.1) Rupture and Burst

The methodology requires defining the parameters of the failure event, and then calculating the required air intake
at each point to prevent vacuum conditions.
The required air intake will be calculated according to one of the following formulas:
a. Rupture

n Qair - Required air flow (m3/hr)

n A – Pipeline cross section flow area (m2)
n ∆h - Elevation difference between pipeline failure point to the position of the air valve (m)

b. Burst (Hazen Williams equation SI units)

n Qair - required air flow (m3/hr)

n C – H.W coefficient
n D – Pipeline diameter (mm)
n S - Pipeline slope (m)

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2.2) Drainage
This calculation refers to the required air intake through the Kinetic Orifice, while the pipeline is being drained in a
controlled manner, taking into account drainage valves sizes and positions along the pipeline.
The required air flow will be calculated according to the following formula:

n Qair - Required air flow (m3/hr)

n A – Drainage valve cross section area (m2)
n ∆h - Elevation difference between drainage valve and air valve (m)

Size Selection (based on the calculated required flow capacity)

The selected Air Valve will be the one ensuring the required air intake flow, based on the above calculations, at a
negative inline pressure not lower than the pipeline collapse pressure.
Every pipe material and class has a collapse pressure, which is the negative pressure that will cause the pipe to fail.
This value is defined by the pipe manufacturer. For example, rigid pipes such as Ductile Iron/Steel pipes can handle
higher negative pressures than PVC/PE/GRP pipes, which are more sensitive.
For example – if the requirement for air intake is -1,000 CFM; -1,750 m3/hr at -3 psi; -0.2 bar, then an Air Valve with
an inlet of 4”; DN100 is the right selection. An Air Valve with an Inlet of 3”; DN80 does not have the required capacity.

Air Flows (Normal cubic feet per minute - ncfm)

-2,000 -1,000 0 1,000 2,000
0.4
Down outlet
0.3
4
2”
Pipeline Pressure (bar)

0.2
Pipeline Pressure (psi)

3”
2
0.1
4”

0 0

-0.1
-2
-0.2
2” -4
-0.3 3”
4”
-0.4
-4,000 -3,000 -2,000 -1,000 0 1,000 2,000 3,000 4,000
Air Flow (normal cubic meter per hour - nm3/h)

Graph 6.1 – Selecting the size of the Kinetic Orifice for pipeline draining

Actual air flow capacity of an air valve, when it is being tested in specialized air flow test bench, might be 50% lower
in comparison to calculated air flow capacity based on theoretical formula.
It is important to consider only air valves, which were tested in specialized air flow test bench according to the
requirements of EN-1074/4 or AS4956 standards.

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3) Sizing the Automatic Orifice (Air Release)

In steady state, under pressure of 14.5 psi; 1 bar (at 77°F; 25°C) water contains about 2% solubility of air.
According to Henry’s Law, the amount of dissolved air is in direct proportion to the pressure. At higher pressure, water
contains higher amounts of air and vice versa. Therefore, at those points where pressure may drop (high points and
others as detailed in chapter #5), air bubbles will be formed.
A conservative method is to allow each of the automatic air valves along the pipeline to release this 2% of airflow rate.
However, this method will require surplus units of air valves, especially at short distance and large diameter pipelines.
As long as the automatic orifice diameter is larger than; 1 millimeter, the air valve will efficiently release entrapped
volumes of air along the pipeline, whether is very large pipe to a small pipe. Thereby, sizing an automatic orifice for
every given location is inessential. The designer must verify the existence of an automatic air valve for a given location,
according to the guidelines in chapter #3.

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Chapter 7 - BERMAD AIR - Sizing & positioning software

Introduction
Proper air control is a vital factor in water systems design. Appropriate sizing and positioning of air valves are critical
to avoid water hammer and head loss, while achieving optimal efficiency and increasing the system’s life time.
Selecting the right valves is a complex and time-consuming task that requires the designer to take a great number of
factors into account, in addition to adjusting the system costs to the budget framework.
Informed selection of air valves
BERMAD AIR software is a state of the art, water system design tool meant to help the designer in selecting the best
valves for optimized air control in water pipelines and networks while reducing the costs of the project.
The software is an engineering tool, including algorithms based on common sizing methods such as AWWA-M51. It
enables every designer to reach an educated decision regarding the selection of air valves, while examining various
“what if” scenarios.
BERMAD AIR modeling is especially useful for designing long water transmission lines, utilizing either pump-reservoir
systems or gravity systems. Using Bermad-Air will achieve the following goals:
n Protection against vacuum conditions and pipeline collapse due to drainage or burst.
n Safe and controlled pipeline filling within a reasonable time.
n Enhanced system efficiency during pressurized operation.
n Improved Surge Protection solutions.
n Reduced air valve procurement costs.
Registration and uploading of project data
BERMAD AIR is available free of charge to any water system designer. It is a standalone software that can be downloaded
onto any personal computer. Click here to register and download Bermad Air.

Picture 7.1 – BERMAD AIR’s user interface

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Scenarios for Analysis

Based on the project data, BERMAD AIR analyzes the required airflow rate at various scenarios including:
n Pipeline filling
n Burst or Rupture
n Drainage

n Maximum distance between nodes

n Column separation

n Critical velocity

According to the analysis results and the designer’s specifications, the software automatically selects Air Valves’ features
(including quantity, material, diameter, connection type, coating, outlet, and others) for the recommended solution,
along with catalog numbers for each unit.
BERMAD AIR main features
n Real air release and air intake data
Air valve selection is based on actual airflow measurements for each model and size, to ensure optimal design.
The valves’ data used in BERMAD AIR is a result of testing Bermad air valves in an Air Flow Test Bench, according
to standards EN-1074/4 and AS4956 and represents the real and actual, not theoretical, performance.
This contributes to lowering procurement costs, by avoiding oversized and/or unnecessary valves.
n Easy data upload – Users can upload data manually or directly from AutoCad or MS Excel.
n Eliminate errors due to inaccurate topographical calculation
High points along the pipeline are critical locations in the analysis. About 80% of the air valves are located at high
points. Therefore, determining the high points properly to prevent inefficiency is essential.
n Comprehensive applications
BERMAD AIR offers integration of pressure reducing valves, drainage valves and consideration of demand nodes.
n Integrated graphic display and reports interface – BERMAD AIR’s drag-and-drop interface is one of the most user-
friendly in the industry. Once generated, the report includes:
{ System data

{ Parameters taken into consideration

{ List of selected air valve models and their features

{ Chart with location of the Air Valves at each node

n Reports includes complete BOQ can be downloaded into PDF or Excel files
n Full technical support – If required, the project can be e-mailed to BERMAD’s Application Engineers for further
technical support.

NOTE
BERMAD-AIR is designed based on real flow rates measurements of BERMAD air valves. Hence result are valid for
BERMAD products only. It's incorrect and risky to consider BERMAD-AIR results for another air valve manufacturer,
especially with regards to the difference in performance for both inflow and outflow.

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Chapter 8 – Preliminary sizing graphs

Bermad Application Engineering approach is always to use Bermad Air Sizing & Positioning software for professional
and accurate sizing of Air Valves. However, for a purpose of preliminary selection or a rough order of magnitude,
the following graphs can be used.
The following graphs for sizing are based on solely 2 parameters: pipe diameter and pipe gradient (slope).
For example: for a 12"; DN300 pipe with 7m/100m slope, the required air flow rate is 350 m3/hr and therefore
1 unit of C10/30 with an inlet of 2"; DN50 is sufficient.
Combination Air Valves
CFM m 3/hr C10/C30
16”; DN400
3,520 800
2 units X C10/C30 - 2”; DN50

3,080 700
14”; DN350
2,640 600
Required air flow

2,200 500

12”; DN300
1,760 400
C10/C30 - 2”; DN50

1,320 300
C10/C30-SP - 2”; DN50 10”; DN250

880 200
8”; DN200
440 100
C10/C30 - 1”; DN25 6”; DN150

0 0
0 1 2 3 4 5 6 7 8 9 10
Pipeline gardient m/100m ; ft/100ft

CFM m 3/hr C70 Mushroom cover 2" - 6"; DN50-150

32”; DN800
22,000 5,000
C70-M - 6”; DN150

19,800 4,500

17,600 4,000 28”; DN700

15,400 3,500
Required air flow

13,200 3,000
C70-M - 4”; DN100
24”; DN600
11,000 2,500

8,800 2,000
C70-M - 3”; DN80
20”; DN500
6,600 1,500
18”; DN450
4,400 1,000
16”; DN400
C70-M - 2”; DN50 14”; DN350
2,200 500 12”; DN300

0 0
0 1 2 3 4 5 6 7 8 9 10
Pipeline gardient m/100m ; ft/100ft

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 | Water Control Solutions

CFM m 3/hr C70 Mushroom cover 6" - 10"; DN150-250

80”; DN2000
220,000 50,000
3 units X C70-M - 10”; DN250
72”; DN1800
198,000 45,000

176,000 40,000

154,000 35,000 2 units X C70-M - 10”; DN250 64”; DN1600

Required air flow

132,000 30,000

110,000 25,000 56”; DN1400

88,000 20,000
C70-M - 10”; DN250
48”; DN1200
66,000 15,000
C70-M - 8”; DN200

44,000 10,000 40”; DN1000

C70-M - 6”; DN150 36”; DN900
22,000 5,000
0 1 2 3 4 5 6 7 8 9 10
Pipeline gardient m/100m ; ft/100ft

Sewage & Wastewater Combination Air Valves

CFM m 3/hr C50, C80

24”; DN600 20”; DN500
5,720 1,300
C80 - 3”; DN80
5,280 1,200

4,840 1,100

4,400 1,000

3,960 900 16”; DN400

Required air flow

3,520 800

3,080 700
14”; DN350
2,640 600

2,200 500

1,760 400 12”; DN300

C50 - 2”; DN50
1,320 300
C50-SP - 2”; DN50 10”; DN250
880 200
8”; DN200
440 100
6”; DN150
0 0
0 1 2 3 4 5 6 7 8 9 10
Pipeline gardient m/100m ; ft/100ft

Disclaimer - These graphs are provided “as is” and BERMAD (i) accepts no liabilities whatsoever for any loss or damage
arising from any use of these graphs (ii) shall not be held liable for any damage or loss, caused to ant party arising
from any use of or reliance on these graphs and (iii) explicitly excludes any liability for any claim and liability, regardless
of the form of action, whether under contract, tort, negligence or otherwise at law.
© Copyright Bermad CS Ltd. 2021. All rights reserved.

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 | Water Control Solutions

Chapter 9 - Surge analysis

Introduction
Water hammer or pressure surge is a phenomenon that occurs in water systems with sudden changes in flow velocity.
The consequences can be devastating, both to the system and the environment. Air valves have a fundamental role
in scenarios of transient flow, such as water hammer. The most significant is their air intake capability, in order to
alleviate or eliminate down surge. In addition, air valves are required to prevent water column separation that can
easily enhance surge. On the other hand, uncontrolled air relief during pipeline filling, due to incorrect or over sizing, is
also risky and may lead to secondary surge.
BERMAD’s surge analysis service
Bermad offers a free of charge surge analysis service, as support to system’s designers.
Designers are required to submit an Excel form with all relevant data about the system: pumps, pumping stations
layout, pipeline properties & profile and more.
Surge analysis enables the designer to predict the maximum & minimum pressures along the system under different
scenarios, potentially leading to pressure surge, such as: pumps trip, valve closing, rapid change in demand, etc.
Pumping stations, high peaks and points with low steady state pressure are usually at high risk for down surge.
Performing surge analysis
The software analyzes the air valves performance in various scenarios, allowing the adjustment of the air valves
characteristics for optimal surge elimination. The software addresses the following parameters: air relief, air intake,
surge protection (SP) disc size and switching pressure and more.
Main stages:
A. U
 ploading system data to the surge software while ensuring that the hydraulic conditions in the model are similar
to the data received from the client (Steady State condition).
B. Defining the worst case scenario and running transient (surge) analysis without any protection to estimate the
magnitude of up surge & down surge throughout the entire system.
C. Running several iterations with surge protection devices, seeking optimal product selection to provide the most
cost-effective solution.
D. Summary and formulation of reports.

Picture 9.1 – Surge Analysis software user interface

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| Water Control Solutions

Picture 9.2 - Pressure at the pumping station with and without protection

Picture 10.3 - Maximum & minimum presssure/head along the pipeline

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 | Water Control Solutions

Chapter 10 - Air Valves specifications

Once the designer has decided on the selected air valves, it is important to specify all their requirements in the project
engineering & procurement data. Accurate specifications will ensure compliance with all requirements.
The table below indicates important points for proper air valve specifications.
Click here to download the full Bermad Air Valves specifications document.

Specifications Content
Clean or Non Clean water
Air valves type
Combination, Automatic or Kinetic
Body and Cover construction materials
Construction materials & coatings Type of coating for metal air valves
Internal parts materials
Maximum operating pressure
Operational data Minimum operating pressure (low pressure sealing)
Water temperature
Inlet connection size
Air valve inlet size and connection Threaded - BSP or NPT
Flange - type of standard
Size of the Kinetic orifice
Nominal / Full Bore - equal to the inlet connection size
Airflow capacity from the Kinetic
Reduced - smaller than the inlet connection size
(Air / Vacuum) orifice
Define the required airflow at selected points - negative pressure
(pipeline draining or vacuum conditions) and positive pressure per inlet size.
Surge Protection (SP)
Air valves additional features Inflow Prevention (IP)
Assited Closing (AC)
Type of cover - down, side, mushroom
Service port
Accessories
Insect screen
Drainage valve
Published airflow curves and data have to be based on actual measurements
Testing Capabilities in a specialized airflow test bench (as specified in EN-1074/4, AS4956) including
negative pressure conditions.

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 | Water Control Solutions

Chapter 11 - Installation considerations

This section provides important considerations about how to design air valves installation for optimal operation.
Riser
Air Valves have to be installed on vertical risers, at a 90º angle to the horizon. Non-vertical installation may disturb the
air valves proper performance. The risers diameter has to be equal to the air valve inlet diameter or larger.
The riser should ideally be within 5 degrees of vertical for optimum operation.
Isolation valve
To allow maintenance, isolation valve must be installed between the pipeline and the air valve. During operational
mode, the isolation valve has to be fully opened (not partially).
Ideally the isolation valve should be full port such as a Gate, Ball or Knife valve not to impede the air valve performance.
Butterfly valves can be used to isolate on flanged valves, but could have an effect on operation and air capacity.
They are typically suggested when height is an issue. Ensure butterfly valve model is designed for end of line service
to enable air valve removal under pressure.
Drainage pipe
When required, a drainage pipe should be fitted to the valve’s outlet. The pipe’s diameter should be at least equal to
the inlet size of the air valve. A smaller diameter may reduce the air valve flow capacity.

Picture 10.1 - Air Valve installation

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 | Water Control Solutions

Air collection chamber

It is highly recommended to design a collection chamber (air trap) underneath the air valve. During pressurized operation,
air pockets will be captured temporarily in the chamber, to be released through the automatic orifice of the air valve.

ød h ød h

øD
øD

Picture 10.2 – Air collection chamber

D ≤ 12"; 300 mm 12”; 300 mm<D≤ 60”; 1,500 mm D > 60"; 1,500 mm
ød Diameter ød = D ød = 0.6D ød ≥0.35D
h Height h ≥ D & h ≥ 6” ; 150 mm

* Please note – the table above refers to Combination or Automatic air valves only.
** For Kinetic / Air Vacuum valves, air collection chambers are not needed, consider only the height.
*** In raw sewage systems air collection chambers are not recommended. Since they become trap for wipes, diapers
and other large suspended particles.

Underground / Pit installation

The vent pipes should have an open area of 1.5 times (or greater) of the large orifice of the air valve to ensure correct
performance of the air valve. If the pit has the opportunity to submerge the air valve, then install a threaded outlet air
valve and hard plumb above ground to avoid contaminated water entering the pipeline under vacuum.

Picture 10.3 - Underground Installation

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 | Water Control Solutions

Chapter 12 - BERMAD air flow test bench for air valves

Air valves are simple components, but essential for the efficient operation of water networks and protection from
vacuum conditions. Air in the system has to be controlled by correctly sizing and positioning air valves. Their sizing should
be based on their air flow performance in the real world. Due to the complexity in replicating real operation conditions
with enough air flow capacity, only few manufacturers use air flow test equipment. As part of the development of its
line of air valves, BERMAD has built an advanced and innovative air flow test bench.

Features of a unique test bench

Built in Kibbutz Evron (Northern Israel), this installation has been designed to develop and test air valves up to 8”; DN200
in real conditions of air intake and relief. Its heart is a 350 kW blower, able to generate high flow rates up to 8,500 cfm;
15,000 m3/h and +7.5psi; 0.5 bar positive pressure for air relief and - 7.5 psi; -0.5 bar negative pressure for air intake.
In addition to verifying the BERMAD air valves air flow capacity according to their technical specifications, the test bench
is a basic tool for quality control and for the development of new products. It has been designed according to the
EN-1074/4 Standard, and AS 4956:2017 Australian Standard.
The air flow test bench allows on line data gathering of the pressure, flow and temperature during pipe line filling and
pipeline draining (vacuum condition). This data is presented in the air flow curves in the product pages and also being
used in BERMAD Air data base. The measurements’ results were found to be consistent and repeatable by experts
from the water industry.
Why the test bench is important
On the basis of innumerous tests performed in the BERMAD test bench on different manufacturers’ air valves, we are
able to issue the following recommendations:
n Test results reveal the necessity to choose the air valve according to its air flow capacity and not according to its
inlet connection diameter. This becomes evident looking at the wide gap in the results obtained by valves having
the same inlet diameter but different internal aerodynamic design.
n Having actual air flow measurements, able to replicate real operation conditions, is extremely important.
Air Flow data obtained by simpler methods and mathematical simulations may be far from reflecting reality.
BERMAD-Air (www.BERMAD-air.com) software for air valve's sizing and positioning uses real data as obtained at
our test bench.
n Determining the closing point of the air valve in its air releasing phase is essential to prevent problems derived
from premature closing.

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Chapter 13 – BERMAD Air Valves – Why they are better for your system
Control of air in water systems is as essential as control of water. That’s why BERMAD engineers have devoted years
of reaserch and development to improve air control in water systems focusing on practical performance testing along
with an in-depth evaluation of today’s current range of air valve technologies. This extensive research has led to the
development of an innovative new line of air valves based on the most advanced flow analysis and engineering tools
available. It also led to the development of a unique modern test bench that serves both as a development tool and
a quality assurance tool.

The line of BERMAD Air Valves include Metal Air Valves ranging from 2” to 8” and Plastic Air Valves from ¾” to 2” for a
variety of Water, Sewage and Waste water pipeline and networks offering:
n Higher flow rates - Advanced aerodynamic design with a straight-flow body allowing higher flow rates than ever before.
n Low pressure sealing - all BERMAD Air Valves’ operate with a minimal operating pressure (0.1bar/1.5psi).
n Built-in surge protection (anti-slam feature) - Responds to the approach of high velocity water column by slow air
relief, preventing damage to the valve and to the entire system. Can be added to the air valve after installation.
n Robust design - including solid floats, which designed for intense working conditions and endure pressure surges.
n Certifications - BERMAD Air Valves are certified by international functional standards (EN-1074/4 ,WRAS, AS4956).
The WW models also carry water service standards (NSF, WRAS, ACS, AS4020).
n Reliable air flow data - based on actual air flow measurements in specialized air flow test bench, which
contributes to better system optimization.
n Application engineering support - recommendations based on sizing & positioning engineering tool (BERMAD Air)
and Surge Analysis services.

BERMAD’s advanced line of air valves joins our extensive line of hydraulic control valves to create comprehensive
control solutions for pressurized pipelines and networks. System engineers and end-users can now design and install
far more optimized solutions for their system requirements.

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ISO 9001-2000

Chapter 14 – Bermad Air Valves certifications

Functional Standards

European Union EN-1074/4 C70

Russia GOST A30, C30, C50, C70

CNA
TA
National Quality Supervision and
China C70
TYPE APPROVED

Inspection Centre of Pump and

Valve Products

Bulgaria EN-1074/4
NFPA
®
A10, A30, A31, C30, C70, K10

Drinking Water standards

A30, A31, A71,

USA NSF/ANSI/CAN 61
CQS C30, C35, C70, C75

ISO 9001-2000

UK WRAS A30, C30, C70

Australia AS4020 & AS4956 C10, C30, C70

TA
TYPE APPROVED

NFPA
®

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Chapter 15 - BERMAD Air Valves product matrix

Inlet Connection Sizes

Construction
Pressure

Material
Rating

Model

Body
Type

DM250
DN200

DN300
DN100

DN150
DN25”

DN80
DN50
DN20

10"

12"
3/4"

8"
6"
4"
2"

3"
1”
Automatic; Reinforced
150 psi; PN10 A10
Air Release Nylon

Automatic; Reinforced
230 psi; PN16 A30
Air Release Nylon

Automatic; 230-360 psi;

A71 Stainless Steel
Air Release PN16-25

Automatic; 250-900 psi; Ductile Iron,

A72
Air Release PN16-64 Cast Steel

Reinforced
Combinaton 150 psi; PN10 C10
Nylon

Reinforced
Combinaton 150 psi; PN10 C15
Nylon

Reinforced
Combinaton 230 psi; PN16 C30-P
Nylon

Combinaton 230 psi; PN16 C30-C Ductile Iron

Reinforced
Combinaton 230 psi; PN16 C35
Nylon

230-580 psi;
Combinaton C70-C Ductile Iron
PN16-40

230-580 psi; Cast Steel,

Combinaton C70-S/N
PN16-40 Stainless Steel

230-580 psi;
Combinaton C75-C Ductile Iron
PN16-40

230-580 psi; Cast Steel,

Combinaton C75-S/N
PN16-40 Stainless Steel

Reinforced
Kinetic 150 psi; PN10 K10
Nylon

Reinforced
Combinaton* 150 psi; PN10 C50-P
Nylon

Combinaton* 230 psi; PN16 C50-C/J Ductile Iron

Combinaton* 230 psi; PN16 C50-N/G Stainless Steel

230-360 psi;
Combinaton* C80 Ductile Iron
PN16-25

* For sewage & wastewater

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AIR CONTROL IN WATER SYSTEM - A GUIDE FOR THE SYSTEM'S DESIGNER,

Bermad Disclaimer
You are welcome to use this Guide for the Water System's Designer (the “Guide”) for air-valves purchased from BERMAD
CS LTD. or any of its affiliates ("BERMAD").
The information contained in this Guide should be used only by professional water systems engineers and designers,
who can fully understand it and the risks involved therewith.
Although BERMAD has made every effort to ensure that this Guide is accurate; BERMAD disclaims liability for any
inaccuracies or omissions that may have occurred.
All the procedures, drawings, pictures and any other information provided in this Guide are presented as general
information only, BERMAD makes no commitment to update or keep the information in this Guide current or up-to-
date, and BERMAD reserves the right to make improvements, alterations and modifications to this Guide, at any time
without providing any notice thereof.
This disclaimer will not be deemed to broaden the scope or extend the validity of any warranty given by BERMAD for
the relevant product whilst in no event the liability of BERMAD, whether under contract, tort, negligence or otherwise
at law for loss or damage arising from or in connection with this Guide - shall exceed the purchase price actually paid
by the claimant to BERMAD for the relevant product.
BERMAD explicitly excludes any liability for special, incidental, or consequential damages as well as for defects or
damages resulting from accident, force majeure, inappropriate physical or operational environment, improper installation,
operation or maintenance, or modification, negligence or fault by any party other than BERMAD.

© Copyright Bermad CS Ltd. 2021. All rights reserved.

35
 | Water Control Solutions

About BERMAD
BERMAD is a leading, privately-owned global company and accumulating knowledge and experience
that designs, develops and manufactures tailor-made in multiple markets and industries. Today, we are
water & flow management solutions that include recognized as a pioneer and established world-
state-of-the-art hydraulic control valves, air valves leading provider of water & flow management
and advanced metering solutions. solutions that give our customers the unprecedented
operational efficiency, and superior quality, durability
Founded in 1965, we have spent over 50 years and performance they need to meet the demanding
interacting with the world’s major end users, challenges of the 21st century.

www.bermad.com
The information contained herein may be changed by BERM AD without notice. BERM AD shall not be held liable for any errors.
36 © Copyright 2011-2021 BERMAD CS Ltd. April 2021