Minimum lenght of pipe for freezing?

[NorthBristol]

Hi, I need to change a stopcock. The house does not have an external shutoff! I'm thinking freeze the pipe, but there is only a few inches of pipe showing below the stopcock. What is the minimum length of pipe I can get away with for freezing? Or does anyone have any better ideas. I'm a bit stuck.
Thanks

 

[HERTS P&D]

You would want to be 300mm away from the stoptap, is there an external stoptap/water meter?

Andy

 

[NorthBristol]

Hi Andy, this was previously MOD property. There is a common supply to the whole street with one shutoff valve. I don't know how big that is or whether it's publicly accessible. Currently trying to find out what's involved to get that shut off for a few minutes. There is a manhole at the end of the street. I presume that's it.
Only have about 15cm of copper from emerging from the floor to the stopcock

 

[HERTS P&D]

Find the mains and shutting that off would be the only option, remove stop tap and fit a Pegler lever valve.

Andy

 

[oldbuffer]

1. If you are using an electric freezer you can get away with only a few mm clearance from the freeze head to a fitting. The head itself is about 60 mm wide (varies with make but not by much).
2. Given you have 150mm to play with you should be OK, BUT as soon as it is frozen, get the old stopcock removed fast and get any water remaining in the pipe out of it. Otherwise it will freeze to the top and make getting a new stopcock on very difficult.
3. As suggested by HERTS P& D replace with a Pegler lever valve. Valve closed, attach to pipe, freezer off, connect outlet pipework,

 

[NorthBristol]

Okay, anybody in the vicinity of Stonehenge got an electric freezer and interested in changing a stopcock?