Posted by BTC on January 13, 2000 at 10:30:58:
In Reply to: There are several possible consequences, all of 'em bad. posted by Mike Hinz on January 11, 2000 at 19:56:52:
: Once water gets into the dry pipe it will start siphoning out of the boiler. Believe me, you don't want water leaving the boiler via the steam header! Besides water hammer like you wouldn't believe, it could cause the steam line to rupture.
: For this reason our boilers are equipped with high level whistles and the automatic feedwater valves are set to fail CLOSED in the event of a loss of control. The thinking is that it is better to have the boiler shut down on low water than risk feeding water into the steam line!
I agree that water carry over can have some serious consequences as stated. However I question the reasoning behind having your feedwater control valve set to fail in the closed position.IMHO the primary concern should be in the safe operation of the boiler.Having the control valve fail shut is an invitation to disaster if your LWCO fails.
You didn't state if your boilers were manned or not I'll make the assumption that they are. Alert, well trained operators will identify symptoms (one of which is an alarm)of a high water casualty and take required action to resolve / control the problem before it gets out of hand ie.. control feed manualy, blow down the boiler or secure the boiler.