1. Plumbing Valves

2. Float Operated
Float operated valves control the amount / level of water in the cold water storage tank or cistern.
The float rises and closes the valve stopping the flow of water.
Pictured below is the symbol for a float valve.
There are two main types of float operated valve the Portsmouth and the diaphragm valve.

3. Float Operated Valve Portsmouth
Portsmouth valve this valve is a part one valve; this is indicated by the water outlet being at the bottom of the valve body and the float arm having no method of adjustment.
This type of valve is not to be fitted to a new system. They are sold as they can be fitted as a direct replacement if a part 2 valve cannot be installed due to physical limitations.
This is because the outlet is at the bottom of the valve and there is a possibility that contaminated water may make it back up into the water supply pipe.

4. Float Operated Valve Portsmouth Valve
1. Inlet port
This is where the mains supply water comes into the valve.
Remember that all float valves should have a method of isolation. This allows you to service the float valve without turning off the supply to the entire property. 7 8 9 4 1 3 2 5 10 6

5. Float Operated Valve Diaphragm Valve
Diaphragm (BS 1212 Pt 2) valve should be used in cold water storage tanks and cold water cisterns.
To conform with BS 1212 Pt 2 the level at which the float is set must be adjustable, this can no longer be done by bending the arm.
The outlet is over the top of the valve body greatly reducing the chance of contamination.

6. Float Operated Valve Diaphragm Valve7 8 9 1 6 5 4 3 2

7. Stop Tap / Service Valve
The stop tap and service valve isolates mains pressure water from the system or component allowing the plumber to work of the system without flooding the property.
All float operated valves must have a method of isolating them.

8. Stop Tap
The stop valve is capable of isolating water pressures between 0.5 – 10 bar.
The water flows into the valve and is stopped by the washer at the end of the valve stem.
The stop tap is usually a compression fitting but push fit versions are available.

9. Service Valve
The service valve as the name suggests allows the plumber to isolate an individual component or system part, enabling them to work on the part without turning off the water supply the rest of the property.
The service valve can be screwdriver operated or level operated.
Both types use a highly polished ball with a hole through it seated in a nylon seat as the ball is rotated it aligns the hole with the bore of the pipe allowing water to flow.

10. Gate Valve
Gate valves are used to control the flow of water from the outlet of cold water storage tanks.
Gate valves are used because they offer the least restriction to the flow of water.
Gate valves should not be used on mains pressure pipes as most are not rated for mains pressure.

11. Gate Valve As the valve stem is turned it raises and lowers the gate.
The water seal is achieved between the matting faces of the brass / bronze gate and the body of the valve; no gaskets or seals are used.