On Jul 25, 8:40*pm, Andy Breen wrote:
On Mon, 25 Jul 2011 11:54:33 -0700, harry wrote:
On Jul 25, 10:53*am, Andy Dingley wrote:
On Jul 25, 6:27*am, harry wrote:

No-one in their right mind is going to lose sight of the water level..

A wise idea - mostly because it's very hard to tell if a gauge glass is
full of water or steam, once you've lost sight of the level -
especially on the LMS, where the gauge cocks were linked to a single
handle, so you couldn't blow one at a time.

If you look at a guage glass it has diagonal stripes behind it.

If the glass is full of water they are refracted to the horizontal *as
seen through te sight glass.
If the glass is full of steam, they *remain diagonal. So you know
whether the water level is above or below the glass.

snip..

There are three cocks to every guage glass. Steam side and water side to
isolate the fitting if the glass breaks and drain to blow down each leg
separately *so as to prevent blockages and rings forming on the glass..
There are min. two gauge glasses on ever boiler for redundancy/
camparison reasons
They are all fitted with safety glasses too.

So - what would be the recommended operating method for an early locomotive
with no gauge glasses (and no feed pump - Middleton, early Chapman engines
- or one which might or might not work - Trevithick, Wylam, Killingworth...)?

That's a genuine question - can you, with experience of operating boilers,
cast any light on how such a boiler might be worked best. Because I find
it rather hard to imagine, in spite of reading such accounts as exist from
the time..

--
From the Model M of Andy Breen, speaking only for himself- Hide quoted text -

- Show quoted text -

I think many early boilers operated at such a low pressure (5 or 10
PSI) that water levels and even furnace uncovering was less critical
than in a high pressure boiler. The accidents started to happen when
high pressure steam was introduced. There must have been a lot of
operator guesswork.

If you look at these old boilers, there is a lot of space between the
top of the boiler and the top of the furnace so there was bags of
lattitude in water level.
Modern boilers have a lattitude of only a few cm.

Cast iron boilers would be less affected than wrought iron by an
overheat of the metal.
How would they make the glass tube in the very early days? Must have
been a major problem.