AN IMPROVEMENT OR IMPROVE- MENTS IN SAFETY VALVES
Year: 1857

page_text: LETTERS PATENT to James Webster, of Birmingham, in the County of
Warwick, Engineer, for the Invention of "AN IMPROVEMENT OR IMPROVE-
MENTS IN SAFETY VALVES."
Scaled the 23rd September 1857, and dated the 14th July 1857.
PROVISIONAL SPECIFICATION left by the said James Webster at the
Office of the Commissioners of Patents, with his Petition, on the
14th July 1857.
I, JAMES WEBSTER, of Birmingham, in the County of Warwick, Engineer,
do hereby declare the nature of the Invention for "AN IMPROVEMENT OR IM-
PROVEMENTS IN SAFETY VALVES," to be as follows:-
In constructing safety valves according to my Invention, I place upon that
part of the axis or stem of the valve which is prolonged above the top of the
valve a sliding collar or flange, which is capable of being fixed in any desired
position on the said stem or axis. When the said sliding collar or flange is
adjusted in its lowest position, its under surface constitutes as it were a
horizontal shoulder upon the valve, the said shoulder extending from the top
of the inverted cone forming the valve. When the conical valve is raised
from its seat by the pressure of steam underneath, the steam, after escaping
between the valve and valve seat, acts upon the said shoulder and counteracts
the increased resistance which is offered to the raised valve when the said

page_text: valve is acted on by a spring. By adjusting the said sliding collar or flange
to different heights on the valve stem, the action of the steam upon
regulated.
it
may bo
I sometimes carry my Invention into effect by making the sliding collar in
the form of a piston, fixed on the valve stem as a piston rod; I surround the
said piston with a cylinder, in which the piston works loosely, and perforate
the cylinder with holes, so as to allow the steam to escape when the piston
has risen to the desired height. The action of this modification of my
Invention is essentially the same as that first described.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said James Webster in the Great Seal Patent Office on the
12th January 1858.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
WEBSTER, of Birmingham, in the County of Warwick, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fourteenth day of July, in the year of our Lord One
thousand eight hundred and fifty-seven, in the twenty-first year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
James Webster, Her special licence that I, the said James Webster, my
executors, administrators, and assigns, or such others as J, the said James
Webster, 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 IMPROVEMENT OR IMPROVE.
MENTS IN SAFETY VALVES," upon the condition (amongst others) that I, the
said James Webster, my executors or administrators, 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 James Webster, do hereby declare the
nature of the said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement thereof, that is to say:

page_text: My Invention consists of the methods herein-after described, and illustrated
in the accompanying Drawing of constructing safety valves.
Figure 1 of the accompanying Drawing represents in vertical section a
safety valve constructed according to my Invention. a is the valve; b, the
valve seat; c is the stem or axis of the valve a; and d, the arm or lever by
which the valve a is pressed to its seat by a spring or weight on the pro-
longed end of the said arm or lever d. Upon the stem c of the valve I place
a collar or flange e (shown separately in clevation in Figure 2), the said
collar or flange e is capable of sliding on the valve stem c, and is fixed at the
desired height by the screw f. Around the valve seat I make a short case
or hollow cylinder g, the sliding collar or flange e coming very nearly into
contact with the top of the case or hollow cylinder 9 when the valve a is
upon its scat ; or the short case or hollow cylinder g may be dispensed with,
and the sliding collar or flange e inay be brought down on the stem c, so as
to rest on the top of the valve a; I prefer, however, to use the case g, as'
represented. When the valve a is raised from its seat by the pressure of
steam, the said steam after escaping between the valve and valve seat acts
upon the collar or flange e, pressing the said collar or flange upwards, and
thereby counteracting the increased resistance which is offered to the raised
valve, especially when the said valve is pressed down by a spring. By
adjusting the sliding collar or flange e to different heights on the valve stem c,
the action of the steam upon it may be regulated.
I sometimes make the sliding collar or flange of less diameter than the case
or hollow cylinder surrounding the valve. This modification of my Invention
is represented in Figure 3 of the accompanying Drawing, where h repre-
sents the sliding collar or flange, capable of being adjusted to any desired
height above the valve k in the interior of the case or hollow cylinder i.
Instead of fixing the sliding collar or flange rigidly upon the valve stem,
I sometimes attach it thereto by means of a helical or coiled spring, as repre-
sented in vertical section in Figure 4, in which said Figure is a coiled spring
surrounding the valve stem, and connected at its upper end with the nut m,
and at its lower end with the sliding collar or flange n; the nut m is fixed in
its place by a screw.
I sometimes carry my Invention into effect in the manner represented in
vertical section in Figure 5, that is to say, I make the sliding collar o in the
form of a piston, fixed on the valve stem p as a piston rod; I surround the
said collar or piston and valve seat 9 with a hollow cylinder r, in which
the piston or collar o works loosely. The said hollow cylinder is perforated
with a series of holes s, s. When the valve t has been raised by the pressure

page_text: of the steam, the said steam acting on the under side of the sliding piston or
flange o, raises the said piston or flange until it no longer covers or only
partially covers the holes s, s, when the steam freely escapes by the said
holes s, 3.
Instead of placing a sliding collar upon the axis of the valve, I sometimes
carry my Invention into effect in the manner illustrated in Figure 6, that is
to say, I prolong the valve seat upwards, so as to form a cylindrical casing
around the valve marked u, the said casing being of little larger diameter
than the valve v. When the valve v is closed, the steam acts only on the
under surface of the valve, but as soon as the valve is raised, the steam bears
also against the conical sides of the valve, the area of which is thus virtually
increased. This effect is produced by the casing u, and the action of the
valve is analogous to that of the several valves hercin-beforo described.
By constructing safety valves according to my Invention, when the steam
acquires a sufficient pressure to raise the valve from its scat, the said valve is
raised by the said steam higher than valves of the ordinary construction, and
a free means of escape for the steam provided.
Having now described the nature of my Invention, and the manner of
carrying the same into effect, I wish it to be understood that I do not limit
myself to the precise details herein described and represented, as the same
may be varied without departing from the nature of my Invention; but I
claim as my Invention the methods of constructing safety valves, herein-before
described, and illustrated in the accompanying Drawing.
In witness whereof, I, the said James Webster, have hereunto set my
hand and seal, this Eleventh day of January, in the year of our Lord
One thousand eight hundred and fifty-eight.
Witness,
GEORGE SHAW.
JAMES WEBSTER. (L.S.)