backflow 1#
Which device types are unsuitable for back-pressure protection for any kind of cross connection hazard level?
Pressure-type vacuum breaker and atmospheric vacuum breaker.
Any condition, device or practice that, in connection with the water supply system, has the potential to endanger health.
What hazard am I
mediem
How often must a backflow prevention device be tested?
A Once a month.
B Once every 6 months.
C Once every year.
D Once every 2 years.
E Once every 5 years.
C
What is the common way to protect a SWH system from Legionella bacteria?
Water needs to be heated to at least 60 degrees Celsius to ensure any Legionella (and other) bacteria that might be present is killed off
Where a building has not been specifically designed to support a solar water heater, the pitch of the solar collector is not greater than ___ to the horizontal
45°
Which devices are not suitable for back-siphonage in high cross connection hazard situations?
Double check valves.
Describe the simplest device suitable to prevent swimming pool water returning through a hose tap connection after topping up a pool.
The hose tap connection could incorporate an air gap device.
Who is responsible for organising the periodic testing of a backflow prevention assembly?
A The local territorial authority.
B The installing plumber.
C The architect.
D The building owner.
E An independently qualified person.
D
Name the method by which energy is transferred from the sun to a solar panel.
Radiation
CLADDINGS AND FLASHINGS
The term “hidden” means concealed behind another element such that no part is visible. Hidden elements require a ___ year durability under the NZBC.
50
Give ONE difference between the design of pressure vacuum breakers and atmospheric vacuum breakers.
PVB has a spring. PVB has test points.
this is created whenever the downstream pressure exceeds the supply pressure. This is possible in installations such as heating systems, elevated tanks, and pressure-producing systems
what am I
back-pressure backflow
What is the minimum distance above the highest outlet at which an atmospheric vacuum
breaker can be installed.
A 100 mm.
B 150 mm.
C 200 mm.
D 250 mm.
E 300 mm.
B
Solar water heaters must have a minimum of_____liters of hot water storage per square meter of collector area.
50
Where a building has not been specifically designed to support a solar water heater, the weight of solar collector, including frames, fittings, and heat transfer fluid, has a combined weight of no more than __ kg per square meter (based on the gross area of the solar collector)
22
State the minimum height at which a pressure vacuum breaker (PVB) backflow prevention device on a lawn sprinkler system is permitted to be installed above the highest outlet it serves.
300 mm.
This is the reversal of normal flow in a system caused by a negative pressure (vacuum or partial vacuum) in the supply piping. This can be created when there is a stoppage of the water supply due to nearby firefighting, repairs, or breaks in the city main, and so on. The effect is similar to drinking a can of soft drink by inhaling through a straw, which induces a flow in the opposite direction.
what am I
Back-siphonage
To provide backflow protection, what is the minimum size for an air gap?
A 20 mm.
B 40 mm.
C Equal in size to the inlet pipe diameter.
D 2 × the inlet diameter or 25 mm, whichever is greater.
E 3 × the inlet diameter or 30 mm, whichever is greater.
D
Which system circulates the water directly through the collector for heating before delivering it to the tank for use.
Open loop (direct heating) systems
The term __________ is used to describe thermal movements in a hot water system. That is, these are passive natural convection systems with water circulating within these types of collectors via the ____________ principle:
Thermosiphon
State the minimum height at which the device a atmospheric vacuum breakers is permitted to be installed above the highest outlet it servers.
150 mm
Give the maximum time and reason an atmospheric vacuum breaker is allowed to be continuously pressurized with water.
AVB cannot be pressurized for longer than 12 hours.
The valve has no spring to help it to close. If it is held open for too long there is a higher probability that it could be jammed or seized in the open position and no longer protect against backflow.
Which of the following statements is correct for a bypass fitted to a backflow
prevention installation?
A The bypass must be larger in diameter than the main.
B The bypass must be smaller in diameter than the main.
C The bypass must be the same size as the main.
D The bypass must be constructed of the same material as the main.
E The bypass must provide the same level of protection as the main.
E
Name one component that is used to release pressure build up from a SWH system?
Cold water expansion valve or TPR valve are both components that might be used to release pressure build up, depending on the system.
A solar panel is to be installed on a zinc roof.
Give TWO materials that are suitable to construct a support frame for the solar panel.
Steel, galvanized (unpainted).
Zinc