Ball Valves Flashcards
What is the correct name for a ball valve?
Float operated valve
Define a ball valve?
A ball valve is defined as a control activated by a lever arm and a float
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
