[Steam-engine] relief valves

[Ken Majeski]

Hi Bruce: When I bought mine I got one in 1986 and the other in 1994. I 
specified nothing as far as blowdown is concerened. On is set for 140 and 
the other for 145. They both blowdown about 5 or 6 Psi and close with a 
Foomp and Do Not leak. Yes, they do go off without warning but I can operate 
within a  couple pounds of set pressure without a problem. Yes, I have heard 
of people that have had problems with them and claim they were never any 
good but it hasn't happened to me. When you can have a valve on an engine 
for 18 years without trouble or having it reset I just don't see a 
problem... For what they cost and what labor is worth I would just replace 
them if I had trouble. The Other Ken...

Ken Majeski, Ellsworth Wis. Case Steam Engine, Minneapolis Steam Engine, 
Rumely Oilpulls H, F, & R. Website, Http://www.pressenter.com/~kmajeski/





>From: "Bruce & Marlene Babcock" <babcock2 at gte.net>
>Reply-To: Steam-engine mailing list 
><steam-engine at lists.stationary-engine.com>
>To: "Steam-engine mailing list" <steam-engine at lists.stationary-engine.com>
>Subject: Re: [Steam-engine] relief valves
>Date: Sun, 19 Sep 2004 21:26:08 -0400
>
>Ken,
>
>     Per your request a few days ago, I will offer a few of my "opinions" 
>on
>the subject of safety valves.
>
>     First, in the 1920's and through the 1940's, when boiler manufacturers
>changed from hand-fired boilers to automatically-fired boilers the
>requirements for safety valves changed at the same time.  It seems that by
>the 1950s or 1960s, the bottom-guided valves with either beveled seats or
>wide flat seats were replaced by top guided valves with narrow "optically
>flat" seats.
>
>     In their 1909 Transactions ASME specified, "The function of the safety
>valve is two fold: (a) it gives notice of the highest pressure permissible;
>(b) it gives the alarm that more water or less fuel is needed."  The
>Transactions also state that the purpose of the safety valve is to "...
>simply limit the working pressure under ordinary conditions."
>
>     In the following 90+ years the definition changed.
>
>     In their 2001 catalog Anderson Greenwood Crosby Company clearly and
>simply state the purpose of a modern safety valve:  "A PRV (pressure relief
>valve) is a safety device intended to protect life and property if all 
>other
>safety measures fail."
>
>     Secondly, From 1914 to 1924 ASME specified that blowdown could not be
>more than 6 psi.  At 150 psi this would be 4%.  From 1924 until some time
>between 1983 and 2001 ASME specified that blowdown could not be more than 
>4%
>of the set point.   Today, the ASME Boiler Code allows blowdown to be as
>much as 6% of the setpoint.   It is my understanding that if the blowdown 
>is
>not specified, in most cases, safety valves will be set for 6%.
>
>     Over the last year I have been asking engine owners and operators
>whether or not they are satisfied with their safety valves and how much
>their valves blow down.   It is my "opinion" that owners of safety valves
>that blow down 4% are happier with their valves than are owners of valves
>that blowdown 6%.
>
>     Another opinion.  I suspect that 6% blowdown is more likely to cause
>problems with stays and tubes than is 4%.
>
>     One last opinion.  It is good practice to have your gauge reset before
>you install a new safety valve.  Settings of both blowdown and set point
>have been found to vary from what is stamped on new valves.
>
>Bruce E. Babcock
>
>----- Original Message -----
>From: "Ken Hough " <k4sb at niia.net>
>To: "Steam-engine mailing list" <steam-engine at lists.stationary-engine.com>
>Sent: Thursday, September 16, 2004 9:13 PM
>Subject: Re: [Steam-engine] relief valves
>
>
> > Considering the poor mechanical construction and condition of a NEW
> > safety valve
> > I would rather lift it as a test than not lift at all. However, we
> > have all discussed that a new pop valve nowadays seems to be a one
> > time use device. If it blows it will never seat properly again!
> > Bruce Babcock? Opinions? I think you and I at Wauseon were discussing
> > this.
> > Ken
> >
> >
> >
> > _______________________________________________
> > Steam-engine mailing list
> > http://www.stationary-engine.com/mailman/listinfo/steam-engine
> >
>
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