AN IMPROVED SAFETY VALVE FOR STEAM BOILERS
Year: 1857

page_text: LETTERS PATENT to George Pemberton Clark, of Newark, in the State, of
New Jersey, and United States of America, for the Invention of "AN
IMPROVED SAFETY VALVE FOR STEAM BOILERS."
Sealed the 18th December 1857, and dated the 18th June 1857.
PROVISIONAL SPECIFICATION left by the said George Pemberton Clark,
at the Office of the Commissioners of. Patents, with, his Petition, on
the 18th June 1857.
I, GEORGE PEMBERTON CLARK, of Newark, in the State of New Jersey, and
United States of America, do hereby declare the nature of the said Inven-
tion for "AN IMPROVED SAFETY VALVE FOR STEAM BOILERS," to be as follows:-
In constructing and arranging within the boiler in a box, globe, or cylinder,
an inverted valve opening downwards, but kept & pressed up to its Seat from
below by a spring; this valve is adjusted by the tension of the spring, so as to
sustain a given pressure from the steam above. When the steam pressure is!
greater and the common outside valve has been overloaded, this valve; in-
accessible to the engineer, operates as a tell-tale by giving way or opening, so:
that the steam rushes through the globe & escapes through a pipe to the out-
side of the boiler.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said George Pemberton Clark in the Great Seal Patent Office
on the 18th December 1857.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
PEMBERTON CLARK, of Newark, in the State of New Jersey, and United
States of America, send greeting..
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eighteenth day of June, in the year of our Lord One
thousand eight hundred and fifty-seven, in the twentieth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
George Pemberton Clarke, Her special licence that I, the said George Pem-
berton Clark, or my executors, administrators, and assigns, or such others as I,
the said George Pemberton Clark, or my executors, administrators, and assigns,
should at any time agree with, and no others, from time to time and at
all times thereafter during the term therein expressed, should and lawfully
might make, use, exercise, and vend, within the United Kingdom of Great
Britain and Ireland, the Channel Islands, and Isle of Man, an Invention
for "AN IMPROVED SAFETY VALVE FOR STEAM BOILERS," upon the condition
(amongst others) that I, the said George Pemberton Clark, or my executors of
admistrators, by an instrument in writing under my, or their, or one of their
hands and seals, should particularly describe and ascertain the nature of the
said Invention, and in what manner the same was to be performed, and
cause the same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said George Pemberton Clark, do hereby
declare the nature of my said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and by the
following statement, reference being had to the accompanying Drawings,
and to the letters of reference marked thereon:-
The nature of my Invention consists in constructing an "invisible safety
valve," as herein-after described.
To enable others skilled in the art to make and use my Invention, I will
proceed to describe its construction and operation.
In Fig. 1, A, A, represents a box, globe, or cylinder; B, B, valve seat
bolted or screwed to A, A; C, C, valve, opening inwards and fitted to B, B;
D, D, D, spring bearing against valve C, C; E, set screw to regulate pres-
sure against valve C, C; F, check nut to fix permanently set screw E; G, G,

page_text: bottom plate to secure or enclose the whole above; H; H, bolts to secure the
bottom plate to A, A; I, I, pipe leading through the boiler to the atmosphere;
J, cross bar to turn valve C, C, on valve seat B, B; K, forked stem passing
through boiler to turn valve C, C; L, L, stuffing box to support forked stem
K; M, M, lever outside of boiler to relieve valve C, C, while turning; N, N,
bolts to suspend the whole to inside of boiler O, O; P, P, steam room;.
Q, weight on lever M, M, to ascertain at any time the immediate pressure
inside of boiler, and to detect the overloading of the common safety valve.
In Figure 2, A, A, the globe or, cylinder; B, B, the valve seat; C, C, the
valve, opening inwards; D, spiral spring, either kind of spring may be used;
the eliptical is shown in Fig. 1, D, D.
In the construction of my Invention I place the valve within the boiler in
an inverted position, by which arrangement I am enabled to keep the valve
pressed up against its seat by the spring D more firmly and constantly to do
its work, and I find the action of the steam more effective on the valve from
above, downward through it, and out by means of the tube I, than when
otherwise set. The moment the steam rises above the amount, the valve is
set to carry, the alarm is given, and the extra steam is let off. I have found
that this arrangement of the valve is of great importance when placed inside
of the boiler. By means of the clevis K, I can rotate the valve on its seat, the
whole operating inside of the boiler, the stem of the clevis K only protruding
through it; thus arranged, I have a perfect safety valve and alarm beyond the
control of the engineer, rendering it impossible for him to overload it.
In the operation of my Invention the boiler is supposed to stand with safety
one hundred (100) pounds pressure to the square inch; and the engineer wishes
to carry fifty (50) pounds, but in no case over sixty (60) pounds, he sets
one of these valves (graduated by the maker, and graduated accordingly) at
sixty (60) pounds. The common outside valve through carelessness sticks or
is overloaded by the engineer to over sixty (60) pounds; the instant the steam
exceeds sixty (60) pounds, the valve C, C, gives way, the steam rushes
through the globe A, A, out of the pipe I, I, in the direction of the arrows to
the outside of the boiler; the valve being inaccessable to the engineer, becomes
an instant tell-tale to all within hearing distance, whether engineer, fireman,
passenger, or visitor. It will be seen that as the springs are made adjustable
by means of the set screw E, and as the springs when constructed are set at
the weakest point, say, at forty (40) pounds, then by adjusting the set screw I
am enabled to increase the tension of the spring D¹, until it will bear a pres-
sure of two hundred (200) pounds, thus accomplishing by the same apparatus
what is required by different machines, that is, the ability to vary the pressure

page_text: from forty (40) to two hundred (200) pounds, or more if required. Its
advantages are to supersede the various instruments now in use, including the
fusible plug. It is inaccessible to the engineer, cannot be overloaded, and is
not exposed to the atmosphere, and hence is susceptible to the immediate and
direct pressure of the steam in the boiler, and in instant communication with
the observer.
What I claim under the above in part recited "Letters Patent" as my Inven-
tion, and desire to secure by "Letters Patent" is, the arrangement of the inverted
valve C in globe A, pressed to its seat by the spring D from below or by a
lever, the clevis K, and the escape pipe I extending through the boiler, all
constructed and arranged within the boiler, as described, and for the purpose
set forth.
In witness whereof, I, the said George P. Clarke, have hereunto set my
hand and seal, this Sixteenth day of December, in the year of our
Lord One thousand eight hundred and fifty-seven.
GEORGE PEMBERTON CLAKKE. (L.S.)