IMPROVEMENTS IN SAFETY OR ESCAPE VALVES
Year: 1854

page_text: LETTERS PATENT to William Ashton, of Preston, in the County of
Lancaster, Engineer, for the Invention of "IMPROVEMENTS IN SAFETY OR
ESCAPE VALVES."
Sealed the 24th April 1855, and dated the 27th October 1854.
PROVISIONAL SPECIFICATION left by the said. William Ashton at the Office
of the Commissioners of Patents, with his Petition, on the 27th October
1854.
1, WILLIAM ASHTON, of Preston, in the County of Lancaster, Engineer, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN SAFETY
OR ESCAPE VALVES" to be as follows:-
This Invention relates to a peculiar construction of safety or escape valve,
whether for steam or fluids, whereby an escape aperture is obtained equal in
area to the area of the valve, and consists in the employment of a hollow
piston or tube sliding vertically in a closed outside casing, which is fitted on to
the top of the boiler or other vessel. Only one valve seat is used, the valve
being formed by an enlargement on the upper portion of the tube, the shoulder
of which enlargement rests upon the valve seat when closed. The steam enters
the interior of the tube (which is closed at both ends) by a
and escapes by a similar lateral opening at the upper end.
lateral opening,
As the upper

page_text: opening is of the same area as the valve, an escape will take place equal to it.
The tube is loaded by a weight at its lower extremity.
at its lower extremity. In steam boilers the
valve may be opened or closed by the variation of the water level. This is
effected by employing two eccentrics or cams fixed on to a short transverse
shaft inside the boiler; the cams bear against the under side of the weight, or
against a projection or shoulder thereon, and when the cam shaft turns partly
one way or the other, the cams will turn also, and raise or lower the valve.
The cam shaft is actuated by a lever arm, fast thereon, to which is suspended
a float. This float rises and falls as the water level varies, and therefore
works the lever and cam shaft; or in place of a lever a segment wheel may be
employed. The rod which is attached to the float is continued up through the
boiler, and by the aid of graduated plate serves as an accurate water guage,
although forming part of the safety valve.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Ashton in the Great Seal Patent Office on the
26th April 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
ASHTON, of Preston, in the County of Lancaster, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-seventh day of October, in the year of our
Lord One thousand eight hundred and fifty-four, in the eighteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said William Ashton, Her special license that I, the said William Ashton, my
executors, administrators, and assigns, or such others as I, the said William
Ashton, my executors, administrators, or 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 "IMPROVEMENTS IN SAPETY OR
ESCAPE VALVES," upon the condition (amongst others) that I, the said
William Ashton, by an instrument in writing under my hand and seal,
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.

page_text: NOW KNOW YE, that I, the said William Ashton, 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 and
figures marked thereon, that is to say:-
My said Invention relates to a peculiar construction of safety or escape
valve, whether for steam or fluids, whereby an escape aperture is obtained
equal in area to the area of the valve, and consists, according to one modi-
fication, in the employment of a hollow piston or tube sliding vertically in
a closed outside casing, which is fitted on to the top of the boiler or other
vessel; only one valve seat is used, the valve being formed either by an
enlargement on the upper portion of the tube, the shoulder of which en-
largement rests upon the valve seat when closed; or the tube may be of the
same diameter throughout its lower end, resting when closed on the valve seat.
The steam enters the interior of the tube (which is closed at one or both
ends) by a lateral opening, and escapes by a similar lateral opening at the
upper end, or by the opening left between the lower end of the tube and
the valve seat when the valve is raised. As the upper opening is of the
same area as the valve, an escape will take place equal to it. The tube may
be loaded by a weight at its upper and lower extremity, or at its lower
extremity only. In steam boilers the valve may be opened or closed by the
variation of the water level. This is effected by employing one or more
eccentrics or cams. fixed on to a short transverse shaft inside the boiler;
the cams bear against the under side of the weight, or against a projection
or shoulder thereon, or may work in a recess in the weight, and when the
cam shaft turns partly one way or another, the cam or cams will turn also,
and raise or lower the valve. The cam shaft is actuated by a lever arm, fast
thereon, to which is suspended a hollow float. This float rises and falls
as the water level varies, and therefore works the lever and cam shaft; or
in place of a lever a segment wheel may be employed. The rod which is
attached to the float is continued up through the boiler, and by the aid of a
graduated plate serves as an accurate water guage, although forming part of
the safety valve.
And in order that my said Invention may be more properly understood, I
shall now proceed to describe and refer to the Drawing hereunto annexed.
The accompanying Drawing represents a vertical section of a valve on pre-
cisely the same principle as that herein-before described, but slightly modified
merely in the details of its construction. A is a cast-iron cylinder, bolted on

page_text: to the top of the boiler B; within the central opening C of this cylinder, which
is accurately bored, works the metallic disc or guide D, which is secured to the
valve spindle E. Higher upon this spindle is similarly-secured a tube E,
which is closed by the diaphragm G. The lower edge or lip of this tube
is bevilled slightly, and fits accurately into the valve seating H in the cylinder.
The spindle E is carried up some distance through the tube F, for the purpose
of receiving one or more weights I, which rest upon the upper edge of the
tube. A chain J is attached to the end of the valve spindle, and connected to
an over-head lever handle K, for the purpose of blowing off when requisite, or
for working the valve occasionally to prevent it from sticking. To the lower
extremity of the valve spindle is attached another weight L, having an opening
in its centre, through which opening is passed a transverse rocking shaft or
spindle, M, working in and supported by, brackets, attached either to the boiler
itself, or to the lower portion of the cylinder A. A cam or eccentric N is
keyed on to the shaft. M, and is placed inside the opening in the weight L. O
is a lever arm, which is keyed on to the shaft M, and is connected by a rod P
at its, free end with the hollow float Q, which rests upon the surface of the
water in the boiler. This float is composed of wrought iron, welded all round
the edges, so as to be perfectly steam and water tight. The true level of the
water in the boiler may be indicated on a graduated plate R, fitted on to
the top of the boiler, the index being connected by a rod or link S with the
free end of the lever O. The steam pressure is exerted against both sides of
the guide D and against the under side of the diaphragm G, since the steam is
allowed to enter between the guide and the diaphragm by four lateral steam
ports, only two of which T, T, are seen in the Drawing, which ports are cast in
the sides of, the cylinder. When the valve opens, the lower lip of the tube F
will be raised from off its seating H, and the steam will escape all round the tube,
and out by the lateral openings U in the cylinder, passing thence into the dome
V, and out by the blow-off pipe W. The upward pressure against the diaphragm
G will be equal to the downward pressure on the guide D, until the pressure
under the guide D causes the valve to open, whereupon the steam pressure
inside the valve or tube F will, decrease, and the force of the steam upwards
will assist in raising the valve. The valve will also be opened by the action of
the float Q. should the level of the water in the boiler be either unneces-
sarily high, or dangerously low, in which case the lever arm O will be either
raised or depressed accordingly, and the cam or eccentric on the shaft M
will, by turning either in one direction or the other, elevate the valve spindle E,
and open the valve; the level of the water in the boiler will be constantly

page_text: indicated by the indicator at R, so that a double safety is obtained by this
arrangement, whilst the safety valve itself is internally weighted, and con-
sequently entirely out of the control of the engineer.
Having now described and particularly ascertained the nature of my said
Invention, and the manner in which the same is or may be used or carried
into effect, I would observe, in conclusion, that I do not confine or restrict
myself to the precise details or arrangements which I have had occasion to
describe or refer to, as many variations may be made therefrom without
deviating from the principles or main features of my said Invention; but what
I consider to be novel and original, and therefore claim as the Invention
secured to me by the herein-before in part recited Letters Patent, is,―
First, the general construction and arrangement of escape valve, as herein-
before described, and illustrated by the Drawings.
Second, the application and use of the hollow water and steam tight float,
and the mechanism connected therewith, for the purpose of opening the valve
when the level of the water in the boiler gets either too high or dangerously
low, as hercin-before described.
Third, the peculiar arrangement of water-level indicating apparatus, as
herein-before described.
In witness whereof, I, the said William Ashton, have hereunto set my
hand and seal, the Twenty-fifth day of April, One thousand eight
hundred and fifty-five.
WILLIAM ASHTON.
(L.S.)