Automatic Emergency Water Shutoff Device?


I believe it was on this forum, many months ago, that I read a reference to a device that could be installed in one's water line so that if a pipe burst when no one was at home the water would shut off automatically. I assume the shut-off would be triggered by a sudden heavy and sustained (5 minutes?) increase in water flow.
What are these called? How do they work? I'd like to do a little research on the net and locally, but I have no idea of the proper term.
The only time a pipe burst I was home and able to get the main water valve shut off very quickly. I may not be so lucky next time.
Any help appreciated.
--
----------
CWLee
Former slayer of dragons; practice now limited to sacred
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
http://www.google.com/search?num0&hl=en&lr=&newwindow=1&safe=off&q=automatic+Water+main+Shutoff&btnG=Search
CWLee wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

http://www.dynaquip.com/watercop.asp
Al
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Ditto the gas! -- Mr. P.V.'d (formerly Droll Troll), Yonkers, NY Ever-preparing for The Grand Insertion Party Nominee, IPPVM Independent Party of the Proctologically Violated (M)asses "That's proly not a hemorrhoid you're feeling.... " entropic3.14decay at optonline2.718 dot net; remove pi and e to reply--ie, all d'numbuhs

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
How does it know if some is home? ;-)

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.