IMPROVEMENTS IN SAFETY VALVES FOR STEAM BOILERS OR GENERATORS
Year: 1867

page_text: PROVISIONAL, SPECIFICATION left by Alfred Vincent Newton at the
Office of the Commissioners of Patents, with his Petition, on the
7th March 1867.-A communication from abroad by George William
Richardson, of Troy, in the State of New York, United States of
America.
I, ALFRED VINCENT NEWTON, of the Office for Patents, 66, Chancery Lane,
in the County of Middlesex, Mechanical Draughtsman, do hereby declare the
nature of the said Invention for "IMPROVEMENTS IN SAFETY VALVES FOR STEAM
BOILERS OR GENERATORS," to be as follows:--
In constructing and adapting safety valves for steam boilers it is desirable
to ensure that so soon as the pressure of steam in the boiler or generator
reaches the pressure at which it should be relieved the safety valve shall open
wide for the free escape of steam, and that the valve shall remain open until
the pressure in the boiler is reduced below the pressure by which the valve
was opened; and it is desirable also that a safety valve should be so organized
that the engineer may be able to adjust it, so that it will close at any desired
number of pounds pressure below the pressure at which it will be opened;
to accomplish these results is the main object of the present Invention.
In order to provide a more free escape for the steam than can be obtained
by safety valves, as heretofore constructed, and to ensure the keeping of the
valve open until the pressure of the steam in the boiler shall have fallen below
the pressure which would be required to open the valve the valve is formed
with a surface outside of the ground joint for the escaping steam to act

page_text: against; this extended surface is produced by a cap plate secured to or cast
with the valve in such manner as to leave an open space between the two for
the passage of steam to a central aperture in the cap through which steam can
escape when the valve is lifted from its seat; this central aperture is sur-
rounded by a projecting cylindrical flange threaded on the outside, to which is
fitted a threaded ring that can be turned up or down to any desired elevation,
and there secured by a set screw. A disc-like projection on the valve rod
extends over the said central aperture in the cap plate, and at such an eleva-
tion that the upper edge of the adjustable ring can be set in contact with it,
or let down so far below it as to leave sufficient space for the free escape of
When a spring is used to hold down the valve the increased surface
obtained for the steam to act against will ensure a counteracting force corre-
sponding or nearly so with the increasing tension of the spring as the valve
is forced up. By this means the regulating or adjusting of the area of the
aperture for the escape of the steam beyond the surface outside of the ground
joint may be effected at pleasure. To prevent the guides and stem of a valve
controlled by a spring from binding, and thereby impeding the movements of
the valve the pintle or stem which receives the tension of the spring bears on
the valve, so far below the plane of the valve seat that the force of the spring
shall always be communicated to the valve in the direction of its axis.