Greg O wrote:

"Tom Warner" wrote in message
...

Several reports have stated that the regulator should have prevented too
much
pressure in the house even after the pressure mismatch. Is this true?
Can the
regulator next to the meter reliably regulate when the supply pressure is
that
high?

Then again I don't think there were any other leaks inside houses on that
street
other than the one house that was destroyed, so perhaps everyone else's
regulators worked ok.


Many regulators are designed to handle only so much inlet pressure. Over the
rated pressure they "lock out", or just slam shut, stopping the gas flow. It
is possible that many regulators do not do this, or the diaphragm in the
regulator ruptured from the excessive gas pressure, spewing gas out the
vent.

Last year, I had Keyspan Energy (the same utility that blew up the Lexington
house) replace our regulator. It was making a funny noise whenever the hot
water heater was running. It took quite a bit of time before I figured out that
this strange noise was ocurring when the hot water heater burner was on, and
then that it was actually coming from outside because it sure didn't sound like
it was. Keyspan took four or five four-hour service appointments (most of which
they never showed up) before they finally got it fixed. Along the way they
replaced the gas meter for some reason, but of course that didn't fix the
problem. The problem was the regulator was sucking air in through the vent, and
the diaphram inside was vibrating as air went past, causing the noise which then
resonated through the gas pipes. I've wondered if this air introduced into the
gas line would cause the appliances to operate incorrectly

There are also excess flow valves, which shut off the gas if too much gas enters
the house at once. The NTSB strongly recommends excess flow valves after a
tragic accident that blew up a brand new house and killed a family during their
first night in their new house. Unfortunately they usually aren't required for
new service and cost a mint to install for existing service, and Keyspan said
the customer would have to pay for one if one was available at all. I think
the new propane grill tanks have excess flow valves built in.