[modeleng] Water gauge security
- From: "Ron Head" <ron.head@xxxxxxxxxxxxx>
- To: <modeleng@xxxxxxxxxxxxx>
- Date: Sat, 5 Aug 2006 21:44:29 +0100
Hi all
A incident occurred at my club's track today, the outcome of which could
have been very nasty. A new locomotive that had just been hydraulically
tested was raising steam for the steam test. As full pressure was
approached, the gauge glass started to weep and the owner decided to nip up
the nuts with a spanner. Nothing wrong in that, but what happened next was
most alarming.
The water gauge on this particular loco follows a fairly conventional
design, with top and bottom fittings screwed into threaded bushes in the
boiler. The problem with this design, is to get both fittings pointing in
the right direction so that the glass passes through without binding. The
builder had achieved this by experimenting with copper washers of various
thicknesses, until he was happy that the fittings were tightened up in the
correct orientation.
Now we all know that what is tight in a cold boiler, isn't necessarily tight
in a hot boiler. When the owner tried to tighten the bottom nut, he
succeeded in freeing off the bottom fitting so that it rotated and shattered
the glass. The resulting spray of steam and hot water travelled backwards
out of the cab for a distance of about six feet, and the owner was lucky to
get his hand and face out of the way without being severely scalded.
It occurs to me that no matter whether the top or bottom nut is tightened,
the torque of the spanner will always try to unscrew the fitting. Has
anyone else on this list had a similar problem and if so, what did you do to
overcome it?
Regards
Ron Head
City of Oxford SME
MODEL ENGINEERING DISCUSSION LIST.
To UNSUBSCRIBE from this list, send a blank email to,
modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject line.
Other related posts:
