Cpcpwt4022 a commission-and-maintain-backflow-prevention-devices 2020

Commission and maintain backflow prevention devices
© Commonwealth of Australia 2015 1
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ACKNOWLEDGEMENTS
National Plumbing Services Training Advisory Group
Plumbing Industry Commission Victoria
© Commonwealth of Australia 2015
Construction and Property Services Industry Skills Council
PO Box 151
Belconnen ACT 2616
Tel: 02 6253 0002
www.cpsisc.com.au
This work is copyright, but permission is given to trainers and teachers to make copies and contextualise the resources
for use within their own training organisation or in a workplace where training is being conducted. This permission does
not extend to making copies for use outside the immediate training environment for which they are made, or the making
of copies for hire or resale to third parties.
The work was first published in 2006 with the assistance of funding provided by the Commonwealth Government,
through the then Department of Education Science and Training (DEST). The 2015 publication has been updated to
reflect changes to the national units of competency.
The views expressed in this work do not necessarily represent the views of the Commonwealth of Australia or CPSISC. In
addition, the Commonwealth of Australia and CPSISC do not give warranty or accept any legal liability in relation to the
content of this work.
The website addresses and other contact information provided in this publication were compiled in good faith and were
correct at the time of printing.
The updating of these resources was completed by:
National Plumbing and Services Training Advisory Group, with funding and support provided by the Construction and
Property Services Industry Skills Council (CPSISC):
This guide was developed in consultation with representatives of the Plumbing Industry by NPSTAG and CPSISC
to support the implementation of the CPC08 Construction, Plumbing and Services Training Package.

2 © Commonwealth of Australia 2015
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Acknowledgements
Project reference committee: National Plumbing Services Training Advisory Group
Writer: Paul Carey, Stephen Parker
Technical editor: Rodney Jackson
Instructional designer: Judie Litchfield
Graphic artist: Laura Bito
Word processor: Melissa Rogers

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Contents
Before you begin................................................................................................................. 5
Introduction ........................................................................................................................ 7
1. Hydraulics and hydrostatics as they relate to BPD............................................. 8
1.1 Hydraulics – The study of fluids in motion ....................................................... 8
1.2 Hydrostatics – The study of fluids at rest......................................................... 8
2. Introduction to backflow prevention devices .................................................. 10
2.1 What is a backflow prevention device?.......................................................... 10
2.2 Statutory requirements for BPDs................................................................... 10
2.3 Who has responsibility?.............................................................................. 12
3. A range of backflow prevention devices.......................................................... 13
3.1 Check valves................................................................................................... 13
3.2 Pressure-type vacuum breakers (PVB)........................................................... 14
3.3 Reduced pressure zone devices (RPZ)............................................................ 15
3.4 Registered break tanks (RBT) ......................................................................... 17
3.5 Registered air gaps (RAG)............................................................................... 17
3.6 Line strainers.................................................................................................. 18
3.7 Isolation valves............................................................................................... 18
4. Preparing for the job ....................................................................................... 19
4.1 Know what must be done .............................................................................. 19
4.2 Plan the specific tasks .................................................................................... 20
4.3 Have equipment ready................................................................................... 21
4.4 Plan for safety ................................................................................................ 22
4.5 Prepare the work area ................................................................................... 22
4.6 Required certification..................................................................................... 22
4.7 Quality assurance requirements .................................................................... 23
4.8. Identifying testing and commissioning requirements.................................... 24

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5. The testing and commissioning procedure...................................................... 26
5.1 A basic installation ......................................................................................... 26
5.2 Basic test procedures.................................................................................. 26
5.3 Test completion ............................................................................................. 27
6. Maintenance ................................................................................................... 33
6.1 Meeting requirements ................................................................................... 33
6.2 Safety ............................................................................................................. 34
6.3 Following appropriate workplace procedures................................................ 34
6.4 Quality assurance: whose responsibility? ...................................................... 34
6.5 Required certification..................................................................................... 35
6.6 The procedure................................................................................................ 35
6.7 A checklist of common faults and remedies .................................................. 36
7. Finalisation procedures ................................................................................... 39
7.1 Restoring the work area................................................................................. 39
7.2 Waste disposal ............................................................................................... 40
7.3 Restoring equipment and tools to good working order................................. 40
7.4 Documentation .............................................................................................. 40
Final assessment activity ........................................................................................ 40

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Before you begin
To complete the unit CPCPWT4022A Commission and maintain backflow prevention devices
you may be required to:
• Read the information in this resource
• Complete the resource activities as directed and submit your answers for review or
discussion with your trainer, instructor or supervisor
• Work with your trainer, instructor or supervisor to practise commissioning and maintaining
backflow prevention devices
• Read the final assessment summary together with any additional assessment information
your assessor provides
• Complete the final assessment.
Your assessment in this unit
It is important to note that the role of the assessor in assessing units of competence is quite
separate from the role of trainer, instructor or supervisor. Your assessor for this unit may or
may not be the same person as the trainer, instructor or supervisor who worked with you
during your training. However, your assessment must always meet the requirements of the
unit. You will find references to trainers, instructors or supervisors and assessors throughout
this resource depending on the context.
Assessment in this unit will require you to demonstrate the skills and knowledge needed to
commission and maintain backflow prevention devices.
In many instances, your assessment may involve a combination of methods to ensure the
validity, reliability, flexibility and fairness of the process. If you have any questions about your
assessment, please discuss them with your assessor who will decide with you the specific
details of what you will do. An assessor may develop specific assessment strategies to meet
the requirements of learners.
This unit may be assessed in conjunction with assessment for other units of competence. In
such a case assessment might be based on a task or tasks related to a project that more closely
resembles workplace activities. An appropriate unit for such project-based assessment might
be one that naturally forms part of your workplace responsibilities and roles. Your assessor will
decide if you are to be assessed in this way and will advise you.
Prerequisites units
There are no prerequisite units for this unit. However, this unit has a relationship with
the unit CPCPCM4011A Carry out work-based risk control processes.

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Additional resources
The following resources have been suggested that may help you undertake training and
assessment in this unit. Your trainer/instructor/supervisor may also recommend
specific books, videos and DVD’s.
Note
Standards, websites and codes of practice change, so it is important to keep up to
date. Make sure you always have the most recent edition of the Standards applicable
to your current job. You should also obtain relevant manufacturer information.
Texts
• Building Code of Australia
• Plumbing Code of Australia
• AS/NZS 3500 (2018)– Plumbing and drainage
• AS/NZS 2845.1 Backflow prevention devices – materials, design and performance
requirements
• AS/NZS 2845.2 Registered airgaps and registered break tanks
• AS/NZS 2845.3 Field Testing and maintenance of testable devices

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Introduction
The delivery of water services is based on the sound application of engineering and plumbing
skills and this is very much so with work on backflow prevention devices.
The testing, commissioning and maintenance of backflow prevention devices in water services is
based on clever innovations which are not apparent to the casual observer. Even plumbers who
work with these devices don’t always realise that the ingenuity in them can be traced back to
ancient cities such as those of the Roman Empire, where engineering genius and the skills of the
early plumbers were applied to erect great baths and recreation centres that used water
supplied by aqueducts from sources many miles away.
This unit covers the testing, commissioning and maintenance of backflow prevention devices
(BPD) in water services. The content includes preparing for work, identifying testing and
commissioning requirements, actually testing and commissioning the devices, maintaining them
and finalising work processes. The unit has been designed to help you develop the skills and
knowledge to identify levels of risk/hazard, select the appropriate backflow prevention device
for the job, as set out in AS/NZS 3500, and then do the required work. While a registered or
licensed person can install any of these devices, commissioning, testing and annual retesting
must be done and documented by someone licensed to test backflow prevention devices. This is
a legal requirement.
As you work through the unit, you will complete activities that will help you meet many of the
requirements for demonstrating competency. For assessment, you will test and commission at
least six devices, incorporating double check valves, pressure-type vacuum breakers and
reduced pressure zone devices. Your work will cover situations with low, medium and high risk
of contamination to drinking water and you will be required to assess the ongoing maintenance
requirements for each device. Throughout, you will need to show you can correctly identify
what is needed, work out what you need to do the job and then do it. Your work must be to
specification and must comply with relevant regulations, standards and organisational
requirements.

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1. Hydraulics and hydrostatics as they relate to BPD
1.1 Hydraulics – The study of fluids in motion
Water flow through a pipe is affected by friction restricting the volume of water
delivered at the outlet. For example, in a long length of cement-lined and steel water
mains, the laws of hydraulics apply when rust and scale build-up, increases friction as
water flows through the pipe.
By contrast, smooth-bore pipes of materials such as copper, polyethylene and PVC-U
minimise friction between the pipe wall and the water. Short-radius bends, elbows and
tees used to change pipe direction similarly cause friction. Pressure loss caused by this
friction can be minimised in a variety of ways. Long-radius bends are used where
possible. Pipe ends are de-burred. Care is taken to fully engage pipes into sockets and to
avoid poor joints. Lever action ball valves or gate valves are preferred to stop taps as
they offer less resistance to water flow.
1.2 Hydrostatics – The study of fluids at rest
The pressure exerted by water at the base of a tank is determined by the depth of the
water, or the height of a tank above a water outlet. For example, a header tank ten metres
above an outlet has a pressure of 981 kPa at that outlet, or 9.81 kPa for every metre head
(the measure used to measure pressure when water is static).
Activity 1
1. In the space below, work out the pressure at the base of a column of water 23
metres high.

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2. If A water supply tank is located in the ceiling space of a building. The tank is
4.0 metres above the lowest water outlet and the highest outlet in the building
is 1.2 metres above floor level. In the space below, calculate the pressure at
both outlets.

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2. Introduction to backflow prevention devices
To work on backflow prevention devices, you need a good understanding of the range of
devices and how they are used.
2.1 What is a backflow prevention device?
A backflow prevention device prevents the reverse flow of water from a potentially polluted
source into the drinkable water supply.
The device required in a particular situation depends on how great the risk (or ‘hazard’) is
assessed to be. Cross-connections between elements in a system are rated high, medium or
low risk. (AS/NZS 3500.1 Clause 4.3)
High hazard Any condition, device or practice that might affect a drinking
water supply system in a way that could cause death.
Medium hazard Any condition, device or practice that might affect a drinking
water supply system in a way that would endanger health.
Low hazard Any condition, device or practice that might affect a drinking
water supply system in a way that would create a nuisance
but not endanger health or cause injury.
2.2 Statutory requirements for BPDs
A BPD must be installed in a way that minimises the risk of damage to the device and
injury to whoever will test and/or maintain it.
It may be located:
• At a specific hazard (‘individual protection’)
• On cold water piping to more than one hazard (‘zone protection’)
• At the property boundary after the meter (‘containment protection’).
AS/NZS 3500 and AS/NZS 2845 set out the main requirements for location and
installation of bpds. In particular, you should study AS/NZS 3500 clause 4.6.2. The
following is a guide:
• They must not be located in a corrosive or polluted atmosphere, where
contaminated air can enter the piping system through the air gap or open vent
port and make the device malfunction.

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• They must not be buried in the ground.
• Vented testable bpds must not be located in pits or in cabinets without drainage.
• Containment devices must be located as close to the water meter outlet or
property boundary as practicable. There must be no branch connection
between the meter and the device.
• Insulation or any other protection of the device must not prevent its proper
operation, testing or maintenance.
• If water hammer occurs, it should be stopped. This is done by installing a surge
protector or water hammer arrestor.
• All inline devices must have connections that allow removal and replacement of
the device.
AS/NZS 3500 Clause 4.6.2.2 sets out the requirements to ensure devices are easily
accessible for maintenance or testing without ladders or scaffolding.
All customers connected to the Corporation’s water supply systems in the Northern
Territory must comply with National Code of Practice for Plumbing and Drainage and
AS/NZS 3500.1.
All properties with a water connection that present a high or medium hazard as
defined in Section 4 of AS/NZS 3500.1, shall have the appropriate backflow prevention
device installed at the property boundary. The installation of a backflow prevention
device at the property boundary is to ensure the Corporation’s potable water supply
is protected from contamination from a backflow event.
The type of device to be installed will be determined from Section 4.3 “Cross-
Connection Hazard Rating” and Table 4.1 “Suitability of Devices” from AS/NZS 3500.1.
The customer’s backflow certified plumber or consultant must determine the type of
device that is to be installed.
PWC have determined that all industrial properties will have a testable BPD installed
at the boundary unless the property is certified as a low hazard property by a licensed
plumber holding a backflow tester accreditation or a PWC representative.
Details of testable backflow prevention devices installed at the property boundary
shall be maintained in the PWC “Backflow Register”, these devices will be
commissioned, tested and certified as specified in Section 4.4.6 “Commissioning and
Maintenance” of AS/NZS 3500.1.
Where hazards are assessed as “low”, PWC has no specific requirement for
registration or testing of devices, however, it should be noted that the requirements
of the Building Act may still apply.
Registration and assessment of BPD’s installed on the various zones within a
customer’s internal water supply system are the responsibility of the Industry
Regulator. (Department of Planning and Infrastructure)

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Properties identified as having a hazard that presents a risk to the safety and security
of the potable water supply will be required to install the appropriate backflow
prevention device within an agreed timeframe. Where a timeframe cannot be agreed
upon, or compliance is not achieved within an agreed timeframe, PWC reserves the
right to take action as specified in the Water Supply and Sewerage Services Act.
2.3 Who has responsibility?
Manufacturers, Property owners, system designers, plumbing contractors and accredited
backflow testers have legal obligations in relation to backflow prevention. In addition, they
also owe a duty of care to ensure that the drinking water supply remains safe for the
building occupants and the wider community.
Manufacturers must make sure their valves comply with AS/NZS 2845.1.
After installation the property owner of a testable BPD must:
• Have all bpds installed by a licensed plumber
• Have all bpds commissioned and tested and maintained by a licensed plumbing
contractor endorsed with backflow prevention accreditation. The devices must be
tested at least annually
• Ensure that there is adequate access to bpds for testing and maintenance.
System designers should have up-to-date information on approved BPDs, installation
requirements and applicable codes. They should check with local or regional
authorities to find out whether the system must be approved before connection to
the reticulation system.
Plumbers must have endorsed registration in Water Supply Plumbing. They must
understand the devices they work with and installation requirements.
Accredited backflow testers must hold a current and appropriate endorsement to test
BPDs.

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3. A range of backflow prevention devices
3.1 Check valves
A double check valve provides protection to the drinkable water supply from
contamination in medium-hazard applications such as industrial, commercial and
medical equipment. It also monitors unauthorised usage from fire hydrants and
sprinkler systems.
The valve prevents backflow caused by backpressure, using two independently
operating force-loaded non-return valves. The device also has specific test points for
in-service testing.
A double detector check valve may be used in conjunction with a double check valve
to ascertain water usage as required by local water authorities.
How check valves work
During normal flow conditions, the two check valves are held open, supplying water
downstream. Each check valve is designed to maintain a minimum of 7 kPa across the
valve during normal operation. Should the downstream pressure increase to within 7
kPa of supply pressure, both check valves will close as double protection against
backflow.
Figure 1 – Double check valve

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3.2 Pressure-type vacuum breakers (PVB)
Pressure-type vacuum breakers help protect the potable water supply from
contamination in medium-hazard applications, such as in steam calorifiers, irrigation
systems and chlorinators.
The device prevents backflow caused by back-siphonage. It incorporates a force-
loaded ventilation valve and operates automatically to admit air into the valve’s
downstream chamber whenever pressure in the chamber drops.
How does a PVB work?
Pressure applied to the inlet valve spring opens the inlet valve. This in turn closes off
the ventilation valve by forcing it against its seat. Water then flows to the outlet.
When the water is turned off or the water pressure falls below 7 kPa, the return
spring forces the inlet valve to the closed position. The ventilation valve opens,
allowing air to enter the system and break the vacuum. Water then drains from the
system via the outlet(s).
Figure 2 – Pressure type vacuum breaker

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3.3 Reduced pressure zone devices (RPZ)
A reduced pressure zone device provides maximum mechanical protection to the
potable water supply from contamination in high-hazard applications such as cooling
towers, abattoirs and sewage treatment plants.
It prevents backflow caused by back-siphonage or back pressure in a water
reticulation system.
The device has two independently operating force-loaded non-return valves.
It automatically drains to waste whenever the pressure between the upstream and
downstream non-return valves drops to 14 kPa or more below the pressure at the
inlet to the upstream non-return valve.
A double detector check valve may be used in conjunction with a reduced pressure
zone device to ascertain water usage as required by local water authorities
Figure 3 – Reduced pressure zone device

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How does an RPZ work?
During normal flow conditions, the supply pressure on the relief valve diaphragm,
acting on the internal bypass passage holds the relief valve shut.
The two main check valves are held open, supplying water downstream.
The area between the two check valves the ‘reduced pressure zone’, maintains the
pressure at approximately 49 kPa lower than the inlet supply pressure.
Should back-siphonage or back pressure occur, the second check valve closes,
stopping the backflow of water.
In the unlikely event that the second check becomes fouled, the pressure in the zone
increases, causing the differential relief valve to open to atmosphere. This ensures
that the entire backflow discharges to drain and no potentially contaminated water
enters the upstream potable water supply.

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3.4 Registered break tanks (RBT)
A registered break tank helps protect the potable water supply from contamination in
high-hazard applications, such as in bidets, plant with an auxiliary non-drinking water
supply, and in electroplating, degreasing, de-scaling, stripping and dipping tanks, vats
and vessels.
A registered break tank is a tank system designed specifically for backflow prevention.
It is registered by or on behalf of a regulatory authority to help ensure the inspection
and maintenance that keep the system working as it should.
How does an RBT work?
Water in a supply tank has unobstructed vertical distance between the lowest
opening of the water service or fixed outlet and the highest possible water level of the
tank. This air gap prevents the possibility of backflow and back-siphonage. The gap
must be determined in accordance with AS/NZS2845.2
3.5 Registered air gaps (RAG)
A registered air gap provides protection to the potable water supply from
contamination in high-hazard applications such as in food preparation or food storage
tanks, cooling towers and dockside facilities.
It is a device or system installed for backflow prevention. It is registered by or on
behalf of a regulatory authority to help ensure the inspection and maintenance that
keep the device working as it should.
How does a RAG work?
Water in a supply tank has unobstructed vertical distance between the lowest
opening of the water service or fixed outlet and the highest possible water level of the
tank. This air gap prevents the possibility of backflow and back-siphonage. The gap be
determined by AS/NZS 3500 Table 4.3.

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3.6 Line strainers
A line strainer has a spring-loaded rubber valve which is forced against a brass seat to
prevent rust, scale, etc from the reticulation system entering the BPD and fouling or
damaging the seats. Obviously, such damage would make the device ineffective in
preventing backflow.
Flushing out water supply systems before installation of the BPD also helps minimise
the risk of damage to the device.
Figure 5 – Line strainer assembly
3.7 Isolation valves
AS/NZS 3500 Clause 4.6.1 requires a resilient seated isolation valve immediately
upstream of the line strainer when a testable device is installed. If there is no integral
line strainer, the device must be immediately upstream of the BPD.
Lever action ball valves are the preferred type as they are soft-seated and offer little
resistance to flow.
These valves make commissioning and testing, isolation and maintenance procedures
possible. The isolation valve needs to be in the fully open position when the water
supply is in use (handle facing in the direction of water flow). Alternately, when
maintenance on the BPD is needed, the valve must be in the fully closed position
(handle at right angles to the direction of water flow). The valve should always be left
in the fully open position.

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4. Preparing for the job
Your approach to testing, commissioning and maintenance of BPDs should be much the same
for all plumbing installation work. That is, you should see it as a systematic process with several
key elements. Any other way of approaching the task will almost certainly result in problems
that waste time and may be difficult to fix.
Here are the main steps in the process:
• preparing for the job
• identifying requirements for testing and commissioning
• testing and commissioning the device
• maintaining the device
• restoring the work area.
Each step will be explained in detail in the following sections.
4.1 Know what must be done
Before you begin any work with a BPD, you should familiarise yourself with all relevant
standards, drawings and specifications.
As outlined in earlier sections, you should study AS/NZS 3500 and
AS/NZS 2845 to learn the requirements for location and installation of BPDs. AS/NZS
2845 Appendices D to AP sets out the test requirements for all testable Backflow
Prevention Devices.
Local water authority regulations and requirements must also be considered, and you
might need to consult a hydraulic engineer’s report to find out what type of system is
required (individual, zone or containment). The report might also recommend the
specific type(s) of valve(s) to be installed and where.
Note
Always check manufacturer’s specifications. In specific cases, these might
override industry regulations and standards.

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4.2 Plan the specific tasks
Work out exactly what must be done and in what order. Consider who will do what
and who will be affected by the work.
A site inspection will give you some key pieces of information about an installation,
which is vital to carrying the task successfully and correctly. Some of the things you
might be able to inspect are,
• What type of valve (device) is installed?
• Is the installed valve correctly for the type of hazard to be protected, as per
AS3500 Hazard rating?
• Has the installation been carried out according to AS3500, manufacturers
recommendations and Authorities requirements?
Hints for effective planning
• Communicate your thoughts as clearly as you can. Use simple English so everyone
knows what needs to happen, how it will happen and who is responsible for what.
• Pay attention to how you work with others. Adopt a cooperative, team approach.
• Establish safe and effective work processes that anticipate likely problems and
blockages, and systematically work around them to avoid or minimise reworking
and wastage.
• Use systematic, simple mathematical ideas and techniques to collate applicable
data.

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4.3 Have equipment ready
Your work with BPDs will require you to carefully measure, calculate, check for
accuracy and record results efficiently. You will also need to calculate materials
required. This will involve the use of calculators, levelling systems and a range of other
tools and equipment, using the workplace technology which is available to you.
To test a BPD, you will need a test kit similar to the one shown in the diagram that
follows. The kit has a differential pressure gauge which you attach to the test taps on
the BPD via a series of valves and hoses. You then open and close the valves in a set
order, depending on the type of device you are testing.
The differential pressure gauge must be properly maintained. A certified technician
must recalibrate it annually (or more often depending on local water authority
requirements).
Figure 6 – Typical test kit

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4.4 Plan for safety
Commissioning and testing a BPD usually means working in an unfamiliar
environment. That means you must take care of your own safety and the safety of
others. You must know and comply with all relevant OH&S requirements and any Safe
Work Method Statement (SWMS).
Before starting the job, clear the work area of any obstructions. If barricades, signage
and alternate walkways are needed, make sure they are in place. Use a neon tester to
check for stray electrical current in the water supply system. Reduce the risk of
electrocution by putting bonding straps on both sides of any disconnection point, and
by having rubber matting or timber platforms to kneel on.
Don’t let water discharge from a test point onto any nearby electrical equipment.
If a BPD is installed in a pit, use a gas detection device to be sure the pit holds no
poisonous or explosive gases. You must use a harness in conjunction with a tripod and
have help readily available in case a dangerous situation arises.
If a BPD is installed in an elevated position, the use of scaffolding reduces risk. If the
BPD is fitted to a fire service, a drop, in water pressure might set off fire alarms, so
make sure you tell the fire brigade and area wardens what you are doing before you
begin.
4.5 Prepare the work area
As well as making the work area safe, you must also make sure it is prepared in a way
that allows you to do the job well and efficiently.
4.6 Required certification
Any person entering into a contract to test and maintain BPDs must ensure that the
person doing the testing is licensed. They must also make sure local water authority
and Australian Standards testing and maintenance requirements are met. In some
circumstances, organisational requirements will set down more regular testing.

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4.7 Quality assurance requirements
Quality assurance will depend on the particular workplace, but you must identify what
is needed for programmed maintenance and make sure it will happen.
During building construction or renovation, the licensed plumber must identify what
type of BPD is needed by checking the job plans and specifications. Make sure the
plans have been approved by the local water authority by checking for the 75 mm
square stamp on the appropriate page(s) of the working drawings.
You must also determine environmental requirements and make sure they will be
met. Any hazardous chemicals or substances must be reclaimed, stored and disposed
of in compliance with Environment Protection Authority (EPA) requirements.
When installation, testing and commissioning are complete, a Certificate of
Compliance must be lodged with the Plumbing Industry Commission, with a copy to
the building contractor
(or the owner if more appropriate). You must also notify the local water authority so
they can register the installation of the BPD.
Testing and inspection are then required every 12 months. We will discuss this
requirement more in a later section.

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4.8 Identifying testing and commissioning requirements
Testing and commissioning BPDs is always a complex task. Because it must comply
with the relevant standards, procedures used do not differ dramatically from job to
job or location to location, but nevertheless the specifics of what you do and how
depend on what you learn from a range of documents, such as job specifications,
standards, authorities ‘requirements and so on. It is therefore vital that you know
where to get the information you need and how to apply it.
Your main sources will be:
• Regulations and other legislative requirements, particularly those pertaining to
plumbing regulations, building codes, OH&S and environmental requirements
• Relevant Australian Standards including AS/NZS 3500.1, AS/NZS 2845.2 AS/NZS
2845.3
• Manufacturers ‘specifications and instructions
• Employer requirements
• Instructions from other authorised organisational or external personnel.
You can find out about correct service/system design as well as testing and
commissioning requirements from the BPD manufacturer’s maintenance manual. You
can get these manuals on the Internet or in hard copy form delivered to you with the
device. The relevant local water authority will have specific requirements for test
reporting to document the work procedure and for quality assurance processes for your
testing equipment.
As discussed earlier in this unit, once the BPD is installed and registered with the local
water authority, the responsibility for meeting ongoing requirements then rests with the
owner/occupier.
If building ownership changes, the incoming owner/occupier has responsibility.
Find out the hazard rating
AS/NZS 3500 Table F1 sets out the hazard rating and required protection of fixtures
appliances and apparatus. Check Table F2 to determine the hazard rating and required
protection at the connection to the specific section of the water supply system. Table F3
helps you determine the hazard rating and required protection at the boundary of the
property to protect the network utility’s water supply, or mains water, from
contamination.

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Activity 5
You have been given the task of installing BPDs in a metal finishing plant. You have
prepared for the work and are now at the stage where you need to obtain vital
information on the service/system design, and of the requirements for testing and
commissioning it.
Explain how you would do that.
Explain the type of backflow prevention devices that are likely to be used.

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5. The testing and commissioning procedure
5.1 A basic installation
As you have already learned, installation and testing of BPDs must comply with
relevant standards, job specifications, manufacturers’ recommendations and
authorities’ requirements.
The following is an outline of the basic steps that would be followed in installing a
double check valve (DCV). It is also a general guide to the steps for installing any
testable backflow prevention device.
• Install the DCV. It must be easily accessible for periodic testing and maintenance.
• Flush all upstream piping thoroughly to remove foreign matter.
• Install the BPD. For ease of maintenance and testing, position the device
horizontally and leave some clearance between its lowest part and the floor or
flood grade.
• After installation, close the downstream or number 2 shutoff valve, pressurise the
device and bleed air through test cock number 3. Then open number 2 shutoff
valve.
Remember
The device must be tested periodically in compliance with local
requirements (at least once a year, but more often if service conditions
warrant).
5.2 Basic test procedures
Refer to AS2854.3 Field testing and maintenance of testable devices or
manufacturer’s instructions.

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5.3 Test completion
Make adjustments as needed
When testing is complete, you should always be prepared to make adjustments as
needed, based on your testing. Then make sure you document everything you have
done and submit your completed test report to the local authority (PAWA), you keep
a copy and a copy shall be delivered to the owner of the device?
Note
Testing should consider the full range of conditions that may impact on
the device.
Document your testing
On the following page is the annual testing procedure flow chart from Power Water
showing the progression of annual testing requirements.

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Test report
Owner/occupier: Location of device:
Address:
Contact person: Date of test:
Make: Size:
Model number: Serial number:
Individual □ Zone _ Containment □
Test results
Reduced pressure zone device Pressure vacuum breaker
Double check valve assembly Relief valve Check valve Air inlet
1st
check 2nd
check
Initial test DC closed tight
…… kPa
Leaked
Closed
tight □
Leaked □
Opened at.……
kPa
…… kPa
Leaked _
Opened
at……kPa
Did not open □
Repairs and
materials used
Test after
repairs
DC closed tight
□
RPZ…... kPa
Closed
tight □
Opened at……
kPa
…… kPa Opened
at……kPa
Company
name:
Certified tester:
Address: Signature:
Witness:
Signature:
License
number:
Date: _ Pass _ Fail
Certificate of compliance number:
Test kit serial number: Date test kit last certified:
Place of certification:
Figure 9 – Example of typical inspection and maintenance report
Activity 6

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Read the description below of a real-life project.
Think about the problems that arose in that project and how you would deal with
them. Then write your responses in the table below.
A cooling tower has been installed in a commercial laundry.
The water supply to the cooling tower has a quick-fill valve to allow initial filling and
later refilling.
It has a float valve to keep a constant water level in the cooling tower reservoir.
An air gap must be provided to prevent backflow and this air gap must be registered
with the local water authority.
The air gap must be determined by the size of the opening in the quick-fill valve, not
the ball float valve (using Table 4.3 from AS/NZS 3500.1).
The cooling tower needs a chemical dosage pump to minimise algae, scaling and
corrosion. A hose bib is needed to help with chemical mixing and cleaning of the
tower. The bib must be protected to the same rating as the cooling tower (high
hazard). Annual testing (or testing as required by the local water authority) must be
done by a person licensed by Power Water for backflow testing.
A scheduled maintenance plan is needed to ensure proper protection of the potable
(drinking) water supply. Copies of the test report must be given to the
owner/occupier and the local water authority when testing is completed.
Explain how you would deal with the following situations from the above scenario.
Situations that occur on the job How will you deal with these situations?
Excessive pressure and flow rate
Requirements for installation and
testing seem unclear.

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How will you deal with these situations?
Testing equipment seems faulty.

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6. Maintenance
As well as testing and commissioning, you must also be familiar with the ongoing
service/maintenance requirements for BPDs. As a general rule, these requirements are
determined by manufacturers’ specifications and authorities’ requirements, particularly
those relating to plumbing regulations, building codes, OH&S and the environment.
Sometimes, other relevant factors must be taken into account.
6.1 Meeting requirements
As you already know, AS/NZS 3500 - 4.4.6 requires testable backflow devices to be
commissioned and tested after installation and before use. It also requires them to be
maintained in working order and tested for this at least yearly.
AS/NZS 3500.1 Water Supply – Acceptable Solutions is also relevant.
Reduced pressure zone devices, double check valve assemblies, pressure type vacuum
breakers, registered break tanks and registered air gaps can only be installed when there is
a defined program in place for maintenance, registration and test certification. Otherwise,
where there is no such program, these devices must not be fitted, and the standard air
gap requirements apply.
All work must comply with manufacturers’ recommendations for the device and for
individual components. Parts from different manufacturers are not interchangeable.
Valves might look similar and parts from different sections of the valve might look similar,
but you should never attempt to interchange these parts (springs, valve seats, etc).
During testing, the line strainer must be checked to ensure it is fitted in the right place,
with the correct direction of flow and minimum clearances. These requirements must be
maintained in compliance with AS/NZS 3500 Clause 4.6.3.1 and AS/NZS 2845.

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6.2 Safety
As with testing, you must follow standard operating procedures during maintenance work
to minimise the risk of injury to workers and people in the immediate area.
Potential risks to the safety and health of workers and others must be minimised as far as
practicable and you must notify all relevant people before any shutdown of the water
supply to the area. In some instances, shutdown may have to be documented and signed
off before any work starts.
6.3 Following appropriate workplace procedures
As with testing and commissioning, you must work out who will be affected by the
work and how. For example, if you are to service a device in an existing building, you
must seek permission to enter and locate the device and notify the owner/occupier
that the water must be temporarily turned off. Testing a BPD requires no-flow
conditions, but if a commercial or industrial operation needs uninterrupted water
supply for cooling and boiler feed, etc, a ring main or parallel supply may be needed.
This situation is most likely with hospitals and continuous process industries where
water cannot be cut off without a planned and coordinated shutdown.
While testing is underway, trying to use water will reduce supply pressure to zero and
if unprotected cross connections exist, back-siphonage might contaminate the
building’s water supply. When you seek permission for shutdown, you should
therefore advise the owner and/or occupiers to not use water until testing is finished
and normal water supply restored.
6.4 Quality assurance: whose responsibility?
After testing and commissioning are completed and the Certificate of Compliance and
reporting requirements have been met, quality assurance (programmed maintenance)
becomes the responsibility of the building owner. As you have already learned, the local
water authority registers the installation and will require inspection and testing every
twelve months. The local water authority will send the owner a reminder notice before
each inspection and test is due. It is then the owner’s responsibility to have the valve
inspected and tested by a licensed plumber before the due date. Random audits are
carried out by the local water authority on the documentation of this annual procedure.
The local fire authority and area warden (if applicable) should be notified of the
maintenance work because a drop, in water pressure might activate fire alarms.

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6.5 Required certification
Any person entering into a contract to test and maintain BPDs must ensure that the
person doing the testing is licensed. They must also make sure local water authority and
Australian Standards testing and maintenance requirements are met. In some
circumstances, organisational requirements will set down more regular testing.
6.6 The procedure
The following is a general outline of what you will be required to do as a plumber with
responsibility for the maintenance of BPDs:
Step 1: Request permission has been permission from owner/occupier to enter facility.
Step 2: Obtain permission from the owner/occupier or their representative to shut
down water supply.
Step 3: Advise owner/occupier not to turn on water supply during testing.
Step 4: Determine the type of device to be tested.
Step 5: Determine the manufacturer of the device to be tested.
Step 6: Determine the direction of water flow.
Step 7: Identify test cocks and open them sequentially to flush foreign matter.
Step 8: Connect testing adapters to test cocks.
Step 9: Shut off inlet and outlet isolating valves.
Step 10: Dismantle and clean out line strainer and reassemble.
Step 11: Turn on inlet isolating valve.
Step 12: Connect test kit to appropriate test points.
Step 13: Test as required, using the appropriate procedure.
Step 14: Check replacement components using the documented procedures.
Step 15: Decide if replacement and/or repairs are needed.
Step 16: Ensure that replacement and/or repairs accord with specifications.
Note
It is recommended that you use a checklist such as the above to assist you
when servicing and maintaining backflow prevention devices. The checklist
helps you carry out tasks in the right order and reduce the likelihood of
accidentally skipping steps.

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6.7 A checklist of common faults and remedies
Symptom Cause Corrective action
1. Relief valve
continuously
discharges during
no-flow condition.
No 1 check valve is fouled
with debris.
Inspect and clean seat disc and seat.
No 2 check valve is fouled
with debris and there is
backpressure condition.
No 1 check poppet stem is
not moving freely in the
guide (or no 2 check poppet
during a backpressure
condition).
Inspect for debris or deposit on poppet
stem or guide.
2. Relief valve
discharges
continuously during
flow and no-flow
conditions.
Relief valve is fouled with
debris.
Inspect and clean relief valve seat disc
and seat.
Damaged diaphragm (allows
water to pass through from
inlet to zone).
Replace diaphragm.
Sensing passage to inlet side
of diaphragm plugged.
Inspect and clean passage in cover and
body.
No 1 check poppet stem not
moving freely in poppet
guide.
Inspect for debris or deposits on poppet
stem or guide.
3. Relief valve
discharges
intermittently in a
‘spitting’ action
during no-flow
condition.
Pressure fluctuations (water
hammer) from supply.
Eliminate or reduce pressure
fluctuations.
4. Relief valve does
not open during
field test 1.
No 2 shutoff valve not closed
completely.
Close no 2 shutoff valve or inspect for
possible through leakage.
Test equipment improperly
installed.
Recheck test procedure.

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5. No 2 check valve
fails to hold
backpressure.
No 2 shutoff valve not closed
completely.
Close no 2 shutoff valve or inspect for
No 2 check valve fouled with
debris.
moving freely in guide.
stem or guide.
6. Pressure
differential across
no 1 check valve is
low during field test
3 (does not meet 3
PSID minimum).
No 1 check valve fouled with
debris.
Upstream pressure
fluctuations causing
inaccurate gauge reading.
Eliminate pressure fluctuations.
stem or guide.
7. Check valve fails
to hold 1 PSID.
Shut off valve not closed
completely.
Close #2 shut off valve or inspect for
Check valve fouled with
debris.
Check poppet stem not
Inspect for debris or deposit on poppet
stem or guide.
Table 2 – Checklist of common faults

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Activity 7
Based on what has been covered in this unit and from your own experience, you should
already understand what is normally required with plumbing maintenance. Ongoing
maintenance means more than just checking to see whether ‘things are still working’ and
replacing the pieces that are no longer working satisfactorily. It also means sound
preparation, a clear understanding of specifications and what can go wrong in water systems.
Ongoing maintenance requires you to:
• assess the maintenance tasks
• assess what is required and how it should be done in the most efficient way
• ensure that the water system will continue to run efficiently without breakdowns.
In the space below, explain in your own words what you think are the major factors involved
in the maintenance of backflow prevention devices.
Think about a recent job you have worked on where sound maintenance processes have
produced a good result. Describe how these sound maintenance processes made a difference to
the efficiency of the water system operation.

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Explain the likely short-term and long-term effects of poor maintenance procedures for backflow
prevention devices in water systems.

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7. Finalisation procedures
7.1 Restoring the work area
All plumbing work requires you to properly restore the work area. Because plumbing work
often impacts on the environment, this aspect of your work must be addressed as part of
the workflow.
Restoring the work area requires you to repair any damage to the site. For example, you
might need to fill in or cover holes. If soil has been removed or moved, you will need to
replace it to the natural surface level. You might need to sweep and wash down the area
to restore it to its original state. If a device is located in a pit, the pit lid(s) must be
replaced in a way that avoids creating a trip/fall hazard. You will also need to remove all
waste materials in accordance with requirements of government and environmental
authorities.
Guidance on the restoration of work areas involved in all plumbing work is provided by:
• local, state and national governments’ legislation and regulations
• Environment Protection Authority (EPA), with particular reference to hazard
control and the disposal of hazardous materials and substances
• manufacturers’ recommendations and workplace procedures
• quality assurance requirements, including International Standards
• company quality assurance policies and risk management strategies
• site safety plan and workplace operations and procedures.

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7.2 Waste disposal
As with all domestic industry worksites, the removal of waste products is the
responsibility of the subcontractor if the building contractor has not provided a waste
removal system. Commercial and industrial worksites usually have such a system in
place.
You must ensure refuse or waste material is recycled in the right way. If disposal is
needed, it must be in accordance with Environment Protection Authority and local
council regulations.
7.3 Restoring equipment and tools to good working order
Tools and equipment must be removed from the site, repaired or maintained as
needed and properly stored. The practice of cleaning your equipment before
returning it to its allocated position in the work vehicle or the lockup site shed ensures
that it is maintained in good working order. It also helps to give it a longer working
life.
7.4 Documentation
You must complete all required documentation on environmental impact, recycling
and/or disposal.
Final assessment activity
Your final assessment in this unit will require you to test and commission two each of high,
medium and low hazard backflow prevention devices, incorporating at least two different
double check valves, two different pressure type vacuum breakers and two different reduced
pressure zone devices.
You will also be required to indicate the ongoing maintenance requirements for each of the
devices.
Throughout your assessment tasks, you will need to show you can correctly identify the
location, design and details of the proposed work, correctly select and use appropriate
processes, tools and equipment, work to specification and in compliance with regulations,
standards and organisational quality procedures and processes.
Please refer to your assessor for precise details of your assessment tasks.

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