Backflow Prevention ASHRAE : American Society of · PDF fileBackflow Prevention ASHRAE :...
Transcript of Backflow Prevention ASHRAE : American Society of · PDF fileBackflow Prevention ASHRAE :...
Backflow Prevention
ASHRAE : American Society of
Heating, Refrigeration and Air-
Conditioning Engineers
Dubai, April 12th, 2016
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Watts Water overview
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Mission
To improve comfort, safety, and quality of life for people around the world through our expertise in a wide range of water technologies.
To be the best in the eyes of our associates, customers, and shareholders.
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Industry – Leading Brands
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SOCLA, Key numbers
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4, facilities (France and Germany)
74, M€ 2014 annual sales
300 employees
6 500 Customers worldwide
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Presentation description
Backflow Prevention
This presentation serves as an introduction to further the understanding of the basic principles of backflow, various hydraulic systems used to protect the environment from contamination of potable water sources.
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After this presentation, you will be able to perform the following tasks:
• Explain the basic concepts and definitions of backflow
• Identify the risks and select the means to prevent pollution
• Understand basic types of hydraulics equipment that control backflow
Presentation description
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Scope of Standard BS EN1717
Introduction : what is a Back Siphonage – Pressure Backflow?
Determination of fluid categories which are – could be in contact
with potable water
Determination of installation characteristics
How to determine the protection units
Matrix of protection units
Protection devices to prevent pollution by backflow
Guide table
Presentation Outline
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Protection against pollution of potable water in water installations and
general requirements of devices to prevent pollution by backflow
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• BS EN1717 : 2000 - Scope
The standard deals with the means to be used to prevent the pollution of potable water inside premises and general requirements of protection devices to avoid pollution by backflow.
The hygiene protection specifications of this standard are applicable to all the standards for systems or appliances connected to the private supply system for water intended for human consumption
This standard specifies the minimum requirements for product standards of protection units.
The product standards are used to detail product specifications. In the absence of a product standard, this standard is used as a reference in order to draw up a specification for the products out of new development.
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Backflow Prevention
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Water installations, due to their design or construction shall not be liable to generate pollution of public,
or private potable water supply system by residual matters, harmful water or any undesirable substance.
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Analysis method of the risks at the point of use and choice of
protection
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A backflow of fluid in a potable water supply system can occur by:
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Back siphonage: by a partial vacuum (drop in pressure) in potable water supply system (due for example to the bursting of pipe, the operation of a booster pump, excessive water demands in a part of the system, water taken for emergency use from a hydrant)
Back siphonage
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• Pressure backflow: by a back pressure originating in a non-potable system in which the pressure exceeds the pressure in the potable water system.
Pressure backflow
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Determination of fluid categories which are or could be in
contact with potable water
(1) The boarder between Cat 3 and Cat 4 is in principle LD50 = 200mg/kg body weight in reference to the EU Directive 93/21 EEC dated of April 27th, 1993
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Fluid representing a human health hazard due to the presence of microbiological or viral elements
Fluid representing some human health hazard due to the presence of one or more toxic or very toxic substances (1) or one or more radioactive, mutagenic or carcinogenic substances
Fluid representing some human health hazard due to presence of one or more harmful substances (1)
Fluid presenting no human health hazard. Fluid recognized as being fit for human being, including water taken from a potable water distribution system, which can have undergone a change in taste, odour, colour or temperature (heating or cooling)
Water to be used for human consumption coming directly from a potable water distribution system
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Determination of the installation characteristics
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Pressure: define whether the protection point (existing or foreseen) or failing this,
the point of connection of the apparatus is subjected to atmospheric pressure (p=atm)
or to a pressure exceeding atmospheric pressure (p>atm)
The situation will be p=atm if the protection point (existing, foreseen) or, failing this,
the point of connection of the apparatus to the potable water network is located above the
Maximal operational level.
The situation will be p> atm if the protection point (existing, foreseen or, failing this,
the point of connection of the apparatus to the potable water network is located this maximal
operational level
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How to determine the protection point?
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EA
RT3
EA
RT5
RT1a RT1c
RT1b – RT1d
EAEA
EAEA
EAEA
EA
RT1e
EA
NB
RT2
EA
NP
RT4
NE
NE
NE
Public potable water system
Private potable water system
NB: « branching » level
NP: « branch pipe » level
NE: « equipment » level
RT1: sanitary or alimentary purposeRT2: technical purpose (HVAC)RT3: fire protectionRT4: watering purpose (irrigation)RT5: specific purpose (industrial activities, Laundromat, car wash, …)
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Matrix of the protection units appropriate to fluid
categories
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BP with controllable
reduced pressure
zone
―
BP with different non
controllable pressure
zones
― ―
3 4 5
CA
Fluid category 1 2
BA
Fluid category 1 2 3 4 5
Covers the risk Covers the risk only if p = atm ― does not cover the risk
Controllable
antipollution check
valve
― ― ―
Non controllable
antipollution check
valve
EA / EC
2
EB / ED
Fluid categoryFluid category 1 2 3 4 5 4 5
Only for certain domestic use
1 3
Covers the risk Covers the risk only if p = atm ― does not cover the risk
Hose union BP ― ―Hose union anti
vacuum valve― ―
HA
Fluid category
HD
Fluid category51 2 3 4 51 2 3 4
Covers the risk Covers the risk only if p = atm ― does not cover the risk
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Antipollution check valve type EA
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Many water suppliers are now requiring containment at the water meter as a condition for the water user to receive or continue to receive the public water supply.
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Hose Union Backflow Preventer type HA
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• Backsiphonage protection
• Non-continuous pressure
• Non-testable
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Hose Union Backflow Preventer type HA
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Normal Flow
FLOW
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Hose Union Backflow Preventer type HA
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Backsiphonage
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Hose Union Backflow Preventer type HA
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Backflow preventer with different non
controllable pressure zone type CA
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• Backsiphonage and backpressure protection
• Continuous pressure
• Non-testable
• Occasional water discharge
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Backflow preventer with different non
controllable pressure zone type CA
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Static Flow
60psi
57psi
52psi
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Backflow preventer with different non
controllable pressure zone type CA
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Normal Flow
60psi57psi
52psi
No more than 25psi of loss at rated flow
FLOW
60psi
56psi
51psi
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Backflow preventer with different non
controllable pressure zone type CA
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51psi60psi
Backsiphonage
52psi0psi
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Backflow preventer non controllable type CA
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• Backsiphonage and backpressure protection
• Continuous pressure
• Non-testable
• Occasional water discharge
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Backflow preventer with different non
controllable pressure zone type CA
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Protects against backpressure and back siphonage
SUPPLY
DRAIN
AIR GAP RETURN
WATTS AUTOMATIC FEED VALVE
BOILER
Residential Boiler Installation
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Backflow Preventer with controllable reduced
pressure zones type BA
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51psi60psi 56psi
• Backsiphonage / backpressure protection
• Continuous pressure
• Occasional water discharge
• Install above grade and allow space for normal testing and maintenance
• Typical Use:
• Everywhere – Check with local
Authorities
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Backflow Preventer with controllable reduced
pressure zones type BA
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51psi
60psi 56psi
Static Flow
60psi
57psi
52psi
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Backflow Preventer with controllable reduced
pressure zones type BA
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51psi60psi 56psi
Dynamic Flow
FLOW
60psi
56psi
51psi
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Backflow Preventer with controllable reducedpressure zones type BA
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51psi60psi 56psi
Backsiphonage
0psi 52psi
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Guide table to determining the fluid category
from which protection is required
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51psi60psi 56psi
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Water main protection is our daily concern
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51psi60psi 56psi