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Plumbing Phase 2 Module 2 part 1 > Ball Valves > Flashcards

Flashcards in Ball Valves Deck (20)
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Define a ball valve?

A ball valve is defined as a control activated by a lever arm and a float


What is the correct name for a ball valve?

Float operated valve


What different pressures are ball valves classified as?

High pressure ball valves
Medium pressure ball valves
Low pressure ball valves


Name four different types of ball valves?

Portsmouth ball valve
Croydon ball valve
Garston ball valve
Equilibrium ball valve
Delayed action valve


What dictates the pressure of a ball valve?

The orifice dictates the pressure of a ball valve?


Explain the way the Portsmouth ball valve is designed?

A strong robust valve with parts that are renewable and readily accessible.


List 3 advantages of a garston ball valve?

No water touches any moving part
Easily adjusted for the float
Has fewer working parts than Portsmouth and Croydon ball valves


How does the equilibrium ball valve shut off the water supply?

It utilises the pressure of the water to shut them of


Where are equilibrium ball valves used?? Give 3 places?

Areas where very high mains pressures exist
Confined spaces
We're the pipe is over 2 inch


State Archimedes principle of floatation?

When your floating you exert the same amount of water as you weigh


List 3 defects that can occur with ball valves?

A worn washer which needs replacement
A jammed position due to furring up
A damaged or incorrect size orifice
A faulty float


Explain the term water hammer?

When a high pressure flow of water is stopped abruptly


Explain the term furring in relation too ball valves?

It occurs on the wetted moving parts of the ball valves leaving behind particles of rock like lime


Explain cavitation in relation too ball valves?

Cavitation is a form or erosion, brought about the mechanical wearing away of the ball valve orifice by the formation of air bubbles formed when the water pressure is lowered


Which resists cavitation better brass or nylon orifices?

Nylon orifices are more resistant


What is the purpose of a delayed action ball valve?

To stop noise nuisance and to shut of high pressure water supply


What is a silence pipe on a ball valve?

An outlet is not threaded to receive a silencing pipe as it will cause back siphonage


State another name for garston ball valves?

The BRS or diaphragm ball valve


Explain what principles help a ball valve to shut of the water supply?

Using a rubber valve which flexes against the orifice


Explain the difference between a high and low pressure ball valve?

The difference is the size of the orifice in the ball valve