A New or Improved Safety Relief Appliance for Steam Boilers or other Vessels under Pressure of Steam, Water, Air, or Gases.
Year: 1895

page_text: Date of Application, 1st Apr., 1895
Complete Specification Left, 28th Dec., 1895-Accepted, 15th Feb., 1896
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PROVISIONAL SPECIFICATION.
A New or Improved Safety Relief Appliance for Steam Boilers or
other Vessels under Pressure of Steam, Water, Air, or Gases.
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I, ANTON GEORG SCHAEFFER, of No. 32 Side, in the City and County of
Newcastle-upon-Tyne, Consulting Engineer, do hereby declare the nature of this
invention to be as follows:-
My invention is designed to effect, with certainty, the instantaneous relief of
pressure when the point at which the appliance is adjusted is exceeded,, which
adjustment cannot possibly be. tampered with, and is intended. to, replace safety.
valves. in such cases as where they are liable to get out of, order and fail, to act
from neglect or having been tampered with.
The appliance, in the various forms it, may be used, consists of a diaphragm,
tube or other shaped fitting of any suitable metal or other material and propor-
tioned, as to area exposed to pressure, and the pressure to be resisted, to the
thickness and strength of the material adopted, and fitted to the boiler or other
vessel under pressure in such a manner that it cannot under any circumstances fail
to be burst and be destroyed and the steam, water, air or gas discharged, upon
exceeding the pressure which the appliance is calculated to resist.
As applied to a kitchen boiler to which it is specially adapted. it may con-
veniently be fitted to a plug in the top or other convenient. part of the boiler ip
such manner that when the working pressure is exceeded, the diaphragm, tube or
other form of fitting, being accurately adjusted, cannot possibly be tampered with
and prevented from being burst.
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The diaphragm, tube or other shaped fitting, may be plain or corrugated on the
surface or may be grooved so as to present a line, or lines, of least resistance
around, or along, which it will rent or burst and may be electro-plated, or other-
When rent or
wise provided with a preservative coating, to prevent corrosion.
burst by the pressure being exceeded the appliance is restored to working order by
another diaphragm or tube being fitted.

page_text: adjustment cannot possibly be tampered with, and is intended to replace safety
valves in such cases as where they are liable to get out of order and fail to act,
from neglect or having been tampered with.
It has special reference to domestic, or what are known as "kitchen" boilers,
though applicable to other vessels under pressure, and I will describe it as so
fitted.
It consists of a hollow plug inserted from the inside of the boiler in a hole cut
in the plate with a flange abutting against the boiler plate around the hole, and
this plug is secured in position by an external nut. The plug internally is
"tapped
so as to leave a projecting ledge to receive a diaphragm of any tough
metal or material, the thickness of which is accurately proportioned to the diameter
of the outlet of the plug, and to the pressure at which it is to act, and is secured on
the ledge by a hollow nut screwed externally into the "tapped "internal thread of
the plug. The diaphragm may be perfectly plain or it may be corrugated, or
grooves may be formed in it, and its surfaces or either of them may be electro
plated or otherwise provided with a preservative coating to prevent corrosion.
The operation of the appliance is as follows:-
When the normal pressure in the boiler is exceeded above a fixed margin, the
diaphragm, by the excess of pressure, is rent and destroyed, and opens the outlet
of the plug to the escape of the steam and water, air, or gases.
The resisting power of the diaphragm is the measure of the safe working
pressure, and it is impossible that this resisting power can be by any means.
increased when once determined, or that it can fail to burst and relieve the boiler,
and the safety_appliance is again put into working order by another diaphragm
being fitted. The diaphragm may be grooved around the circumference of the
outlet so as to form a circle of least resistance which will be first rent.
Instead of a plain diaphragm, I may use a tube flanged at its inner end to rest
upon the ledge of the plug and closed at its outer end which will project some
distance beyond the plug, this tube being so adjusted as to thickness that it will be
split and rent when the pressure is exceeded and the steam and water, air or gases
discharged from the boiler.
DESCRIPTION OF DRAWINGS.
On the accompanying sheet of drawings, my invention is shewn as adapted for
kitchen boilers, the safety relief appliance being of the actual size for such boilers.
When applied to large boilers or steam generators, as an additional safeguard
to the ordinary safety valves, it will be of suitable proportional dimensions, and
may be fixed on any convenient part of the boiler, as it will operate in any
position.
Figs. 1 and 1 shew it half in section and half sectional plan through the
line - Fig. 1. as inserted from the inside of the boiler, preferably screwed
into the plate in any convenient position; and Figs. 2 and 24 as screwed into the
plate from the outside when access to the inside of the boiler is not conveniently
obtainable.
Referring to Fig. 1, A is the hollow plug screwed into the boiler plate B, from
the inside, and secured by a nut C. outside. This plug has upon it an internal
flange D, and is tapped internally to receive a hollow nut E screwed into it by a
canted or milled collar F. Between the internal flange D. and the bottom of the
hollow nut E. is inserted the diaphragm G preferably having a thin ring of some
suitable packing on each side. The diaphragm G. may be of any tough-metal,
alloy of metals, or other material, but from experiments I have found mica to be
admirably adapted for it being unaffected by extreme heat or cold or by corrosive
action, of foliated structure, capable of being split into leaves or discs of any
degree of thinness, proportioned to the diameter exposed to pressure and the
pressure above that in the boiler, at which it is intended to act. When any other
metal, alloy of metals, or other material is used, the diaphragm may be corrugated

page_text: with circular grooves, or a groove may be formed around it through which it will
first be rent, and may be coated to protect it from corrosion. The diaphragms
will be supplied, with the safety appliance, of the exact resisting thickness.
adapted to the area of surface and the pressure at which they will be destroyed,
calculated from bursting tests made for reference. When a tube is fitted
closed at the outer end, it will be similarly proportioned as to thickness to.
split and rend along its length, but I prefer a diaphragm fitted as herein before.
described.
Figs. 2 and 24 will be readily understood without further description, the letters
of reference applying to the same parts as on Figs. 1 and 14 where such parts
occur.
In some cases there may be fitted on top of the hollow nut E a pipe to convey
the steam, water, air, or gas to the chimney or back of the boiler seat, but I
prefer to leave the hollow nut quite open so as to offer no obstacle to the free
escape when the diaphragın bursts.
A light hood H. may be fitted loosely over the aperture of the hollow nut to
prevent soot or dirt entering and collecting on the diaphragm or injury to it, and
this hood, when carried away by the bursting of the diaphragm, can be readily
replaced when a new diaphragm is fitted.
Having now particularly described and ascertained the nature of said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
A safety relief appliance for water heating or steam generating boilers, or for
other vessels under pressure of steam, water, air, or gases, consisting of a diaphragm
fitted into a seat, screwed into or otherwise secured to the boiler or vessel under
pressure; said diaphragm being accurately proportioned in thickness to the area
exposed to pressure and to the pressure to be resisted before being burst or rent,.
or the alternative form in which a tube closed at the outer end is fitted of such
thickness as will be burst or rent when a certain pressure is exceeded; substantially
as described.
Dated this 28th day of December 1895.