IMPROVEMENTS IN SAFETY-VALVES
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by the said David Cockburn at the
Office of the Commissioners of Patents on the 1st November 1882.
David Cockburn of Glasgow in the County of Lanark, North Britain, Engineer,
"IMPROVEMENTS IN SAFETY-VALVES"
This Invention which relates to Improvements in safety valves has reference to
that class of safety-valves which have a top plate against which the steam acts so
as to facilitate the rising or opening of the valve when Steam is blowing off.
According to the present improvements the seat of the safety-valve is constructed
or formed with an inclined surface projecting upwards from it all round and the
underside of the plate is made flat with the central part tapering down towards the
seat of the valve.-A hollow is formed round the feathers or guides at the under
part of the valve to facilitate the escape of steam

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said David Cockburn in the Great Seal Patent Office on the 30th April
1883.
DAVID COCKBURN, of Glasgow, in the County of Lanark, North Britain Engineer.
"IMPROVEMENTS IN SAFETY-VALVES,"
My said Invention which relates to Improvements in safety valves has reference to
that class of safety valves which have a top plate or flange against which the steam
acts so as to facilitate the rising or opening of the valve when Steam is blowing off.
According to the present improvements the seat of the safety valve is constructed
or formed with an inclined surface projecting upwards from it all round and the
underside of the top plate or flange is made flat with the central part tapering
down towards the seat of the valve whilst the top plate or flange projects over the
inclined annular seat in such a manner that when the Boiler pressure is sufficient
to raise the valve in the slightest degree the steam is directed up the annular
incline and strikes the flat plate at the outside of the periphery thereof where there
is the greatest surface to act upon and therefore the greatest power to raise the
valve thus effectually preventing accumulation of pressure in the Boiler.-After.
the valve has risen-and-is-beginning. to. shut, the sharp edge on the top of the
annular incline cuts the steam rising against the top plate thereby giving
smoothness and elasticity or a cushioning effect to the descent or closing of the
valve.
This form of valve lends itself easily to any variety of circumstances as when
the Boiler pressure is low, the top plate or flange is mado large, when the Boiler
-pressure is-great the said plate or flange is made smaller. .but this remark refers
only to the top plate, the annular seat boing always as hereinafter described and
shewn by the annexed Drawings.
The essential novelty of this Invention then consists in giving a straight lead of
steam up the incline to the outside of the plate hence the power and sensitiveness
of the safety valve so constructed.-A hollow may be formed round the feathers or
guides at the under part of the valve to facilitate the escape of steam.
And in order that my said Invention may be properly understood, I now proceed
more particularly to set forth the system mode or manner in or under which thie
same is or may be used or practically carried into effect reference being had to the.
accompanying Drawings and to the Letters and Figures marked thereon that is
to say
:
.
Figure 1, is a vertical section of one form of safety. valve constructed according
to my present Invention.
Figures 2, and 3, are respectively front elevation and vertical section, the latter
taken on the line A, B, Figure 2, of another form of safety valve constructed
according to my present Invention.
Figure 4, is a part vertical section and part elevation of another form of safety-
valve constructed according to my present Invention.
Figure 5, is a part vertical section and part front elevation, and Figure 6, is a side
elevation of a double safety valve constructed according to my present Invention.
Figures 7, and 8, are respectively vertical section and part plan of another form
of safety valve constructed according to my present Invention.
In carrying my invention into practice, I form the seat a, of the safety valve (as
shewn in the several Figures) with the inclined surface b, projecting upwards from
it all round and the underside of the top plate or flange of the valve is made flat
as represented at c, whilst the central part d, tapers down towards the seat a, of
the valve. The hollows e, are provided round the feathers or guides f, at the under
part of the valve to facilitate the escape of steam when the valve is opened.

page_text: The safety valve represented at Figure 1, is carried in the pipe g, which is
secured by the flange h, to the boiler or other apparatus for which a safety valve
is required. The valve being loaded by the weights i, carried on the frame j, which
is suspended upon the valve d, by the pin k, for the reception of whose lower end
the valve has formed in it the hollow l
In the safety valve represented at Figures 2, and 3, the valve is fitted within
the chamber m, with the outlet at n, and the valve plate c, is loaded by the
weights i, which are carried on the collar o, secured as shewn to the spindle p.-
The lower end of this spindle p, bears upon the valve plate c, and at the part where
it passes through the cover q, of the valve chamber m, it is provided with the
Bush T.
For the loading or adjustment of the safety valve represented at Figure 4, there
is provided the spring 8, whose lower end bears upon the valve, within the hollow
or receptacle, formed therein for that purpose and whose upper end is received in
the adjusting bolt t, which is fitted in the frame u, secured to the flange h.
With reference to the double safety valve represented at Figures 5, and 6, it will
be seen that the pressure of the spring v, in compression, is exerted against and
between the valve d and the adjustable collar w, the valve & being keyed at x, to
the spindle y, upon which is formed the collar s, and upon which collar, the loose
collar a, rests. The compression of the spring v, may be increased or decreased
respectively by tightening or loosening the nut b₁-The safety valve as shewn is
provided with the necessary guide Bushes r, at those parts where the spindle y,
passes through the covers of the chambers, and it is also provided with the
outlet c'.
The safety valve represented at Figures 7, and 8, is carried in a flanged casting d',
upon which is fitted the flanged cylinder e¹, at whose interior the guides f¹, are
formed, which keep the spindle g', in its proper position.-From the top of this
spindle g', the weights i, are suspended, being carried upon the frame h¹.
Having now described and particularly ascertained the nature of my said
Invention and the system, mode, or manner in or under which the same is or may
be used or practically carried into effect, I would observe in conclusion that 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 :-
The safety valve top plate or flange and seat, constructed substantially, as
herein before described with reference to the accompanying Drawings.
In Witness Whereof, I, the said David Cockburn, have hereunto set my hand
and seal this twenty-eighth day of April in the year of our Lord One
thousand eight hundred and eighty-three.