AN IMPROVED PRESSURE INDICATOR AND TELL-TALE FOR STEAM GAUGES, APPLICABLE ALSO AS A SUPPLEMENTARY SAFETY VALVE."
Year: 1878

page_text: PROVISIONAL SPECIFICATION left by Ellis Marsden at the Office of the
Commissioners of Patents on the 30th August 1878.
"
ELLIS MARSDEN, of Liverpool, in the County of Lancaster.
AN IMPROVED
PRESSURE INDICATOR AND TELL-TALE FOR STEAM GAUGES, APPLICABLE ALSO AS
A SUPPLEMENTARY SAFETY VALVE."
My Invention relates to an improved construction of instrument or apparatus to
be used as a preṣusre indicator and tell-tale, or pressure test for ascertaining and
correcting inaccuracies in steam gauges.
The instrument or apparatus can also be used as a "supplementary" or test safety
valve.
An instrument or apparatus constructed according to my Invention consists of a
novel arrangement of parts, constituting a sensitive safety valve in combination with
a steam whistle alarm.
In carrying out my Invention I use a suitable cock, on which I form (by pro-
longing one of its branches or ways, and countersinking or enlarging at its end the
orifice or way of such branch, and bevelling the periphery thereof) a sensitive valve
seat suitably ground or faced. On the outside of the branch, and embracing the
same, I screw or otherwise attach a valve box or barrel provided with a diaphragm,
dividing the box or barrel into two distinct parts, the part nearest the cock con-
taining the valve, and the upper part being used to apply or contain & lever, spring,
or other controlling mechanism.
The lower portion or valve chamber is provided with a small whistle, screwed
or otherwise attached to the outside of the valve chamber, and communicating
therewith.
The valve is formed in a piece with the valve spindle, which passes through the
diaphragm and through the cover, which serve as guides.
The valve is by preference a disc-face valve of sawcer construction, with its rim
bearing on the rim of the valve seat, forming therewith an extremely sensitive
arrangement.
Above the diaphragm the valve spindle is provided with a loose washer, bearing
on a shoulder formed by turning down or reducing the upper portion of the spindle,

page_text: which passes through an oval slot in a controlling lever, and thence through the
covor, and is then provided with a milled thumb and finger nut, attached by means
of a pin passing through an oval slot in the spindle, and used for hand turning the
valve on its seat.
The controlling lever is by preference a weighted lever of the second kind, which
bears upon the loose washer on the spindle, and has its fulcrum on the valve box or
barrel.
The lever is graded with great precision and nicety, so that the weight may be
set for the valve to blow off at any desired pressure.
The cock is by preference provided with a safety key, which can be removed.
The whole apparatus may be encased or contained in a suitable box with a glazed
or wired front, having outlets or apertures-in the cover of the box.
The instrument is by preference applied to the steam gauge pipe, and is so set as
to act as a test instrument in proximity to the steam gauge, or as a tell-tale.
The instrument may also be applied away from the steam gauge in the engineer's
room or other place, where it serves as an aların in the case of excessive pressures.
It may also be used, as before stated, as, a supplementary or test safety valve applied
in the boiler or engine rooms.
As steam pressure gauges for steam boilers are often inaccurate and liable by uso
to error and false indication, an instrument according to my Invention is of great
value, as providing a means whereby the engineer can readily ascertain with accuracy
the exact pressure in the boilers under his charge, and can make allowances for
excessive or low pressures exhibited by an erring gauge.
I have described ca: construction of valve which I consider most suitable for an
instrument constructed according to my Invention, and also what in my opinion is
the best means of controlling. such valve, but it will be evident that a ball, conical,
of other valve may be used, and a spring, direct weight, or other description of
lever may be used without departing from my Invention, in all cases a means being
provided for setting or moving the valve on its seat by hand,
Ο