Whats the difference between a tap and a stopcock?

[turningtim]

Its not mean to be a joke, but what is the difference (technically) between a tap, a stopcock, a gate vale and a n isolation valve. And when\where do you use each one?

Just ben over to the mother in laws, her late husband was keen on DIY but seems to have used what ever was in the box, each does cut the flow of water to various parts of the house and garden but its a jumbled mess of diferent valves so I was just wondering how and why each should be used. if indeed it matters

ta

 

[Whitespirit66]

A tap is basically a stopcock/tap with an open end to allow water to exit. Stopcocks are usually in a pipeline to isolate the supply of water upstream.

A wheel-head gate valve is similar to a stopcock, but principally designed for isolating gravity-fed supplies, ie. water from storage tanks, not mains pressured water. Gate valves are often referred to as 'full way' gate valves, as when fully open, they offer no resistance to the flow - important with gravity supplies.

Isolation valves take two main forms. The small, inexpensive variety are to isolate supply to a single outlet, eg. toilet cistern or tap. The other type is a full bore isolation valves which when open, don't restrict the flow. Unlike gate valves, there are suitable for mains or gravity pressures. I prefer these as the modern alternatives to gate valves, as they are much less likely to seize up.

Do you have specific questions relating to your mother in law's system?

 

[turningtim]

thanks for the info, I knew there had to be some logic in whats used where. No specific issues with the in laws plumbing just as she's getting on a bit everything needs to be a bit better labeled and identfied and easier to turn off - in a hurry perhaps with more arthritic joints. From what your saying replacing some of the gate vales to the outside taps, garage, green house etc could be repalced with lever operated 1/4turn isolation valves for ease of use. Would these be OK in these more exposed locations?

 

[Whitespirit66]

If the valves are wheel-head gate valves as below, then for someone with reduced strength in their hands, lever full bore valves are a better option. Gate valves are very prone to seizing if not operated regularly, and take a few turns to operate. Full bore valves are OK for any situation where gate valves are used.

Untitled

• Whitespirit66
• 18 Jun 2012
• 2

 

[muggles]

A tap belongs on your sink / basin / bath
A stopcock belongs on your incoming mains
An isolation valve, be it a ballofix, lever, butterfly, service etc belongs on the pipework immediately before any appliance, and should preferably be a full bore type
A gate valve belongs on the Ark