Will someone please explain the different ocassion when one would fit a stopcock versus a gate valve in a domestic cold water system. As both do the same job, it would be interesting to know exactly why. billandhiscat.
Stop cock versus gate valve.
- Thread starter billandhiscat
- Start date
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I dont know why you think they do the same job! They are very different!
A stopcock is designed to positively turn off pressures up to 10 Bar as in water supply mains.
A gate valve is designed to interupt the flow in low pressure systems where the pressures involved are only a few meters head. They are usually used to temporarily turn off supplies for maintenance as in cistern outlets and heating circuits. They may let by a little.
Tony
A stopcock is designed to positively turn off pressures up to 10 Bar as in water supply mains.
A gate valve is designed to interupt the flow in low pressure systems where the pressures involved are only a few meters head. They are usually used to temporarily turn off supplies for maintenance as in cistern outlets and heating circuits. They may let by a little.
Tony
Thanks for the reply. Strangely I have never had such a precise explanation before. Thanks again. Regards, Billandhiscat.
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I don't want to be contentious but have to differ here Agile, gate valves used on water distribution systems are often 16 bar and above and are use for isolation purposes.
The stopcock has a construction very similar to that of an ordinary tap ( it seals by a washer being compressed on to a valve seat) The gatevalve as the name implies shuts off by placing a gate (blade), in the path of the water.
A stopcock is required for isolation of the water supply at entry to the property because the jumper (the part holding the washer) is free to move along the valve spindle and theoretically will close automatically to prevent reverse flow into the water supply (although not all seem to have this facility these days). The stopcock is therefore sensitive to direction of flow and must be installed in the correct orientation, usually indicated by an arrow on the valve body.
The stopcock has a construction very similar to that of an ordinary tap ( it seals by a washer being compressed on to a valve seat) The gatevalve as the name implies shuts off by placing a gate (blade), in the path of the water.
A stopcock is required for isolation of the water supply at entry to the property because the jumper (the part holding the washer) is free to move along the valve spindle and theoretically will close automatically to prevent reverse flow into the water supply (although not all seem to have this facility these days). The stopcock is therefore sensitive to direction of flow and must be installed in the correct orientation, usually indicated by an arrow on the valve body.
Perhaps you work on commercial properties where pressures that high may be found and with high quality gate valves.
Normal domestic grade gate valves rarely hold tight with normal gravity pressures let alone 16 Bar.
Normal domestic grade gate valves rarely hold tight with normal gravity pressures let alone 16 Bar.
I can't reconcile these two statements Crystal. Are you saying that the flow of water tends to push the jumper towards the closed position, or that the reverse flow of water tends to push the jumper towards the closed position? I don't see how both can be true.Crystal said:
billandhiscat - note also that a domestic gate valve, when fully open, is full bore and thus offers negligible restriction to flow, making it better suitable for low pressure applications, whereas a stop cock offers plenty of restriction - not only is it not full bore but the spindle and jumper introduce turbulence.
You might find it interesting to hear that last week I removed a 22mm stop cock that had been installed on the pipe from a cold storage cistern to the inlet on a hot water cylinder, because I couldn't remove the dead mouse carcass that had wrapped itself around the valve spindle (internally). You might think that this was a useful filter, but if a gate valve had been fitted originally then it's unlikely that it would have blocked, resulting in water starvation to the shower pump and increased expense for the customer.
I'd just LOVE the job of removing a mouse carcase from the (wall-embedded) inlet pipe to a shower-valve. Be VERY grateful that it got stuck at the first sticking-point!
I take your point cc, but the answer is to fit a lid on the css, a dip tube on and filter on the overflow, and, if you're really paranoid, filters over the outlets from the css.
Bear in mind also that not all of the carcass stayed within the stop cock....
Bear in mind also that not all of the carcass stayed within the stop cock....
ewww
I had that once, mouse stuffed into a 22mm gatevalve, I undid the gate valve and saw what I thought was the insulation from the CWS so I pinched at it, it crunched so I pulled at it and pulled out a mouse and held it incredulous for at least 30 secs before dropping it and runninng of screaming like a school girl
still makes me shiver
I had that once, mouse stuffed into a 22mm gatevalve, I undid the gate valve and saw what I thought was the insulation from the CWS so I pinched at it, it crunched so I pulled at it and pulled out a mouse and held it incredulous for at least 30 secs before dropping it and runninng of screaming like a school girl
still makes me shiver
You can get a fried Puma PCB without having any mice around!
I once went to a boiler where the PCB had burnt itself out by arcing across the bodies of the cockroaches.
Another had all the interconnecting wires chewed by rats. Took me at least two hours to get that one going again.
Tony
I once went to a boiler where the PCB had burnt itself out by arcing across the bodies of the cockroaches.
Another had all the interconnecting wires chewed by rats. Took me at least two hours to get that one going again.
Tony
This a query I had too....
The cold valve below my sink is weeping at a compression joint, and I intend replacing it as I am "re-jigging" kitchen units and the sink...
It is a 22mm Gate Valve, but is fed directly by the mains. The hot supply is 15mm.
So, do I replace with another gate valve...?
Dougie.
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