IMPROVEMENTS IN SAFETY VALVES
Year: 1876

page_text: LETTERS PATENT to Robert Chapman Anderson, of Wood Green, in the
County of Middlesex, Civil Engineer, for the Invention of "IMPROVEMENTS
IN SAFETY VALVES."
PROVISIONAL SPECIFICATION left by the said Robert Chapman Anderson at
the Office of the Commissioners of Patents on the 6th December 1876.
ROBERT CHAPMAN ANDERSON, of Wood Green, in the County of Middlesex, Civil
Engineer. IMPROVEMENTS IN SAFETY VALVES."
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The object of my Invention of improvements in safety valves for the escape of
compressed steam, water, air, or other vapour, fluid, or gas, from boilers or other
vessels, is to dispense with the usual external weights, levers, and springs. These
external parts are liable to many objections, amongst which may be classed the slow
relief afforded to the boiler or vessel under pressure by a valve so arranged, and
the tendency which such weights, levers, and springs, have to jam the valve in its
seat.
In carrying out my Invention I make use of the same force which presses
upwards against the safety valve to press downwards on a piston connected to the
safety valve in any convenient manner. This piston works in a vertical cylinder
or tube rivetted or otherwise secured to the boiler or vessel, and open at its lower
end, but communicating at its upper end by means of a valve apparatus to be
hereafter described, with the boiler or vessel under pressure. The surface area of
this piston must be at least equal to that of the safety valve; from whence it
follows that these two opposite forces continually counterbalance each other until
the desired maximum is reached, when by means of the valve apparatus already
alluded to, and which I shall hereafter call the " pressure regulator," the communi-
cation between the boiler or vessel and the cylinder or tube is cut off, and at the
same time a small valve or tap or similar device in the top of, or immediately
adjacent to, the cylinder or tube is opened, whereby the pent up force remaining in
the cylinder or tube is discharged into the open air. All pressure being now re-
moved from the piston the safety valve will at once fly wide open, and relieve the

page_text: excess of pressure in the boiler or other vessel. There is scarcely any limit to
the speed with which this relief may be obtained, as there is scarcely any limit
to the size of safety valve which may be employed, and also no obstruction to the
escaping force, as the valve not being encumbered with either weights or springs
will at once open fully to its utmost extent.
The excess of pressure having been relieved the pressure regulator again comes
into action and opens the communication between boiler or vessel and piston, and
closes at the same time the small valve or tap or similar device before alluded to,
the effect of which is that the piston is forced down, and the safety valve closed.
The pressure regulator through which the connection between the piston and
boiler or vessel is made, and which effects the releasing and closing of the safety
valve, consists of a vertical cylinder or tube open at both ends, and fitted to the
boiler or vessel. Into the upper end of this cylinder or tube is inserted a steam-
tight piston, which is connected by means of a spindle or piston rod to a valve,
which is intended to close the lower end of the tube when required. At a point
about midway between piston and valve this cylinder or tube is connected by
means of a short pipe with the cylinder or tube in which the piston attached to the
safety valve works.
The respective surfaces of piston and valve of the pressure regulator must bo
identical in area.
The piston rod or spindle projects upwards from the piston, and carries a
horizontal disc for the purpose of supporting weights, or if preferred, a weighted
lever may be used. The vertical movement of this piston and rod is made use of to
actuate the small valve or tap, which allows the "pent up" force in the safety valve
piston cylinder to escape.
The working of this arrangement of safety valve may be here described :—Suppose
that it is required that the safety valve shall be opened when the pressure in the
boiler or vessel shall exceed 100 lbs. on the square inch, and that the piston and
valve of the pressure regulator have each one square inch of surface, it is only
necessary to place 100 lbs. on the disc, thus the piston and valve will be caused to
descend together to the end of their stroke, and a free communication will be
opened between the boiler or other vessel and the cylinder containing the piston
connected to the safety valve. As soon as 100 lbs. on the square incli is exceeded
the piston of the pressure regulator, and with it the valve, will be forced up by the
pressure, and the said communication will be closed, and at the same time the valve
or tap in the safety valve piston cylinder will be opened. The pressure is now
removed from the upper side of the safety valve piston, and as there is now nothing
to prevent it the safety valve is raised, and the excess of pressure in the boiler or
other vessel is relieved; and as soon as the pressure sinks below 100 lbs. on the
square inch the piston and valve of the pressure regulator again descend, as before,
and open the connection between the boiler or other vessel and the safety valve
piston cylinder, the effect being to force down the safety valve piston and close the
safety valve.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Robert Chapman Anderson in the Great Seal Patent Office on the
6th June 1877.
ROBERT CHAPMAN ANDERSON, of Wood Green, in the County of Middlesex, Civil
Engineer. "IMPROVEMENTS IN SAFETY VALVES."
The object of my Invention of improvements in safety valves for the escape of
compressed steam, water, air, or other vapour, fluid, or gas, from boilers or other
vessels is to dispense with the usual external weights, levers, and springs. These
external parts are liable to many objections, amongst which may be classed the slow

page_text: relief afforded to the boiler or vessel under pressure by a valve so arranged, and
the tendency which such weights, levers, and springs, have to jam the valve in its
seat.
In carrying out my Invention I make use of the same force which presses
upwards against the safety valve to press downwards on a piston connected to the
safety valve in any convenient manner. This piston works in a vertical cylinder
or tube rivetted or otherwise secured to the boiler or vessel, and open at its lower
end, but communicating at its upper end by means of a valve apparatus, to bo
herein-after described, with the boiler or vessel under pressure. The surfaco
area of this piston must be at least equal to that of the safety valve; from whence
it follows that these two opposite forces continually counterbalance each other until
the desired maximum is reached, when by means of the valve apparatus, already
alluded to, and which I shall hereafter call the pressure regulator, the communi-
cation between the boiler or vessel and the cylinder or tube is cut off, and at the
same time a small valve or tap or similar device in the top of or immediately
adjacent to the cylinder or tube is opened, whereby the pent up force remaining in
the cylinder or tube is discharged into the open air. All pressure being now
removed from the piston the safety valve will at once fly wide open and relievò
the excess of pressure in the boiler or other vessel. There is scarcely any limit to
the speed with which this relief may be obtained, as there is scarcely any limit
to the size of safety valve which may be employed, and also no obstruction to the
escaping force, as the valve not being encumbered with either weights or springs
will at once open fully to its utmost extent.
The excess of pressure having been relieved the pressure regulator again comes
into action, and opens the communication between the boiler or vessel and the
piston, and closes at the same time the small valve or tap or similar device, before
alluded to, the effect of which is that the piston is forced down and the safety valve
closed.
The pressure regulator through which the connection between the piston and
boiler or vessel is made, and which effects the releasing and closing of the safety
valve, consists of a vertical cylinder or tube open at both ends, and fitted to the
boiler or vessel. Into the upper end of this cylinder or tube is inserted a steam-
tight piston, which is connected by means of a spindle or piston rod to a valve,
which is intended to close the lower end of the tube when required. At a point
about midway between the piston and valve this cylinder or tube is connected by
means of a short pipe with the cylinder or tube in which the piston attached to the
safety valve works.
The respective surfaces of the piston and valve of the pressure regulator must be
identical in area.
The piston rod or spindle projects upwards from the piston, and carries a hori-
zontal dise for the purpose of supporting weights, or if preferred a weighted lever
may be used.
The vertical movement of this piston and rod is made use of to
actuate the small valve or tap, which allows the pent up force in the safety valve
piston cylinder to escape.
But to make my Invention better understood I will proceed to describe the saine
by reference to the accompanying Drawing, in which Figure 1 is a side elevation,
and Figure 2, a vertical section of a safety valve constructed according to my
Invention.
Similar letters in both the figures represent similar parts.
a is the valve; b, the piston connected to the valve a by the spindle c; d, d, is
the vertical cylindrical tube, in which the valve a and piston b work, such cylinder
being open at its lower end as shewn; e is the pipe or tube forming the communi-
cation between the cylinder d and the cylinder f of the pressure regulator; g is the
valve or tap-for discharging the pent up steam in the cylinder d, as herein-after
described. The cylinder of the pressure regulator is open at the lower end, and
its cover is provided with air holes i, i, or may be completely open. The lower

page_text: part of the cylinder f is fitted into a steam-tight jacket h, open at its lower end to
the boiler or other vessel by means of the tube or cylinder j; is the steam-tight
piston in the upper end of the cylinder f, connected by means of the spindle or
piston rod to the valve m in the lower end of the cylinder f; m, n, holes or parts
in the cylinder above the valve m; o is the horizontal disc above the cylinder f
for supporting the weights p; 9 and 1, are jointed levers or rods connecting the tap
or cock with the disc o. From this arrangement it will be seen that the parts
being in the position shewn in the Drawing the steam, water, air, or other vapour,
fluid, or gas, from the boiler or other vessel will press on the valve a, and will also
pass up the tube j into the jacket h, through the port holes n, cylinder f, tube e, and
consequently press on the piston b; and as the surface area of the piston is slightly
in excess of that of the valve a (to compensate for the friction) the pressure on the
latter will be counterbalanced by the pressure on the former, while the valve m and
piston will be kept in the position shewn by the weights 2, so long as the pressure
of the steam in the boiler does not exceed that due to the weight on the disc o.
The working of this arrangement of safety valve is as follows:-Supposing that
it is required that the safety valve a shall be opened when the pressure in the
boiler or other vessel shall exceed one hundred pounds weight (above that of
the atmosphere) on the square inch, and that the piston and valve m of the
pressure regulator have each one square inch of surface, it is only necessary to place
one hundred pounds weight on the disc o; thus the piston and valve m will be
caused to descend together to the end of their stroke, as shewn in the Drawing, and
a free communication will be opened, as herein-before described, between the boiler
or other vessel and the cylinder d containing the piston b connected to the safety
valve a.
As soon as the pressure in the boiler or other vessel exceeds one hundred
pounds weight (above that of the atmosphere) on the square inch, the piston / of
the pressure regulator, and with it the valve m, will be forced up by the pressure,
and as the valve m will now be above the ports the steam will be cut off from
its communication with the upper part of the cylinder d, and at the same time the
weighted disc o rising with the piston and valve m will by means of the rods or
levers and open the tap or cock g, thereby allowing the pent up steam in the
cylinder to escape. The pressure being now wholly removed from the upper side
of the safety valve piston b, the safety valve a will be immediately raised, and the
excess of pressure in the boiler or other vessel will then be relieved by the steam
escaping through the openings 8, 8, in the cylinder d, and as soon as the pressure
falls below one hundred pounds weight on the square inch the piston and valve of
the pressure regulator will again descend as before, and re-open the connection
between the boiler or other vessel and the safety valve piston cylinder, the effect
being to force down the safety valve piston, and close the safety valve. The
openings 8, 8, may be enclosed with a jacket provided with an exit pipe should it
be desired to carry away the escape steam instead of allowing it to pass direct into
the open air.
q
I would here observe that a pressure regulator of the size shewn in the Drawing
may be employed in combination with a much larger safety valve than that shewn.
Having now described my said Invention and the best means with which I am
acquainted for carrying the same into effect, I wish it to be understood that I do
not confine myself to the precise details herein laid down and shewn in the
Drawing, as the same may be varied without departing from the peculiar character
of the Invention, but what I do claim is,-
Firstly. The general arrangement and construction of safety valves, substantially
as herein-before described and represented in the accompanying Drawing.
Secondly. The construction and employment of the pressure regulator for
operating safety valves, substantially in the manner herein-before described and
represented in the accompanying Drawing.
Thirdly. The arrangement for effecting the discharge of the pent up steam in the
safety valve cylinder by the upward movement of the piston rod of the pressure

page_text: regulator when the pressure in the boiler or other vessel is to be relieved, as herein-
before described and represented in the accompanying Drawing.
In witness whereof, I, the said Robert Chapman Anderson, have hereto set
my hand and seal, this First day of June, in the year of our Lord One
thousand eight hundred and seventy-seven.
Witness,
G. F. REDFERN,
Patent Agent,
4. South Street,
Finsbury.
R. C. ANDERSON. (L.S.)