IMPROVEMENTS IN SAFETY VALVES FOR KITCHEN AND OTHER BOILERS, AND FOR OTHER VESSELS IN WHICH STEAM OR OTHER EXPANSIVE FLUIDS ARE COMPRESSED
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by Alfred Harvey and William Borland,
at the Office of the Commissioners of Patents on the 19th March 1881.
ALFRED HARVEY and WILLIAM BORLAND, both of Glasgow, in the County of
Lanark, North Britain. "IMPROVEMENTS IN SAFETY VALVES FOR KITCHEN AND
OTHER BOILERS, AND FOR OTHER VESSELS IN WHICH STEAM OR OTHER EXPANSIVE
FLUIDS ARE COMPRESSED."
The nature and object of this Invention is the production of an improved safety
valve to be used in or on kitchen and other boilers, or in or on other vessels in
which steam, air, or other expansive fluid or fluids are under compression, which
valve, besides serving the ordinary purposes of a safety valve, is so constructed as.
also to give a continuous audible warning whenever and so long as the pressure in
the boiler or other vessel has reached and remains at or above any given limit to .
which, as affording a reasonable margin of safety, the instrument may have been
set or regulated for the time.
Our valve, as ordinarily made and in its simplest form, consists of the following
parts
First. A tube or tubular piece open at both ends which can be screwed into any
boiler or vessel, so that the pressure of the fluid within the boiler or other vessel
can communicate itself through the tube to the disc or valve hereinafter
mentioned. This tube has an external flange round the top carrying two ears or
snugs at opposite points of the circumference with a hole or aperture in each snug.
into which the legs of the bridge or frame hereinafter described are to be fastened
by means of screws and nuts. The holes are not themselves screwed, the lower parts :
of the legs of the bridge merely pass through them and are secured from rising up out
of the said apertures in the snugs by the nuts preventing them from being pulled.
or forced up out of the same. The upper and interior part of this tubular piece is
socketted and ground to receive and accurately fit the valvular portion or disc
attached to or forming the lower part of the upright spindle or shaft hereinafter
mentioned, in such a way that the said socket and disc shall between them form a
joint or valve, which shall be steam tight at any pressure of the fluid in the boiler
or other vessel less than that of the spiral spring hereinafter mentioned.
Second. A valve arrangement consisting of a horizontal disc or valve ground so
as to fit accurately the above mentioned socket in the mouth or upper end of the
said tubular piece first above described, and also of an upright shaft or spindle
rising from the centre of the disc. The upper portion of the said shaft is reduced.
in diameter to allow the said spiral spring, when the spring is passed over it, to rest
.

page_text: on the circular ledge or shoulder formed by the thicker and lower part of the shaft
at its junction with the slenderer upper part thereof, so that however compressed
from above, the spring cannot descend lower than the said shoulder or ledge, but
when pressed down on the ledge shall press down the spindle, and so in turn press
down the disc more firmly into the socket. The said disc and spindle are free to
move upwards when the pressure of the fluid inside the boiler on the disc is great
enough to lift the disc against the resistance of the spiral spring hereinafter
mentioned, which tends to press the disc down by pressing on the ledge of the
spindle which is fixed in or forms one piece with the disc, and also to move down-
wards when the nuts at the extremities of the legs of the frame or bridge are
screwed home as hereinafter mentioned, so as to make the spring force the spindle
and disc downwards.
Third. A bell-shaped inverted cup which is intended to serve the same purpose
as the analogous bell shaped portion of an ordinary steam whistle, shall be
capable of emitting a continuous whistle or other continuous sound or alarum
when vibrated by a rush of steam or other expanding fluid issuing through the
said tube and valve from the boiler or other vessel. This cup is provided with a
circular hole in the centre of its bottom of about the diameter of the thicker
portion of the said spindle or upright shaft, and the inverted cup is passed by the
said hole down over the spindle, so that the cup shall hang with its mouth.
downwards and with its rim in such proximity to the valve or disc, that when
steam or other expanding fluid is rushing through the same, the rim and sides of
the cup or bell may be vibrated by the steam or other fluid. The diameter of the
inverted cup or bell is about that of the said tubular piece screwed into the boiler.
Around the hole in the bottom of the cup through which the shaft passes there is
formed a collar which is screwed on the outside, by which the cup is fastened to a
corresponding screw in the hole in the lower cross piece of the bridge or frame
hereinafter mentioned, and is suspended therefrom.
Fourth. A bridge or frame consisting of two upright sides or legs connected by
two cross pieces, one at the top, and one further down with its upper surface just
on the level of the said shoulder or ledge in the spindle. Each of the legs is screwed
at the foot in order that they may after passing through the said holes in the ears
or snugs of the tubular piece herein before mentioned, receive nuts which are to be
screwed on to the same to hold the frame down firmly to the said tubular piece.
The said legs are, as aforesaid, at or near the level of the said ledge or shoulder of
the lower part of the upright shaft united by the said lower cross piece, in which
a hole is screwed to receive the screwed collar of the inverted cup or bell, which is
thus held in its place suspended from the said lower cross piece. Above the said
lower cross piece and below the higher cross piece of the frame or bridge (through
both of which the upright shaft passes) there is placed around the said smaller
portion of the shaft a spiral spring hereinafter described. The spring rests on the
said ledge or shoulder of the thicker part of the spindle, which, as already stated,
we make flush with the upper surface of the lower cross piece of the bridge or
frame.
Fifth. The spring and nuts. The spring is a spiral spring which may be of brass
or any other suitable metal, and the thread of which may be either square turned,
or of any other suitable section. It is passed over the smaller portion of the upright
spindle and placed between the two cross pieces of the bridge or frame, so as to.
rest on the ledge of the spindle, and so also as to be in contact when at its natural
tension with the under surface of the upper cross piece, so that when the disc and
spindle are lifted by the steam or other fluid, the spring may at once respond to the
pressure, and also so that when the hereinafter mentioned nuts at the bottom of the
legs of the frame are screwed home, the upper cross piece of the frame may press
the spring down on the ledge or shoulder of the spindle to any extent that may be:
desired, so as to make the spring exert any required amount of pressure against
the fluid in the boiler and thus set it to any required degree of safety. The screwed
portions at the ends or lower extremities of the legs of the frame work after

page_text: passing through the holes in the snugs, have screwed on to each a nut, by which
nuts the tension of the spring can be increased or relaxed according as the said nuts
are screwed home or back, the effect of screwing home the nuts being to cause the
upper cross piece of the frame or bridge to press down upon the spring, and to cause
the spring in its turn to press on the shoulder of the thick portion of the spindle
and thereby to force the disc or the spindle more firmly into its socket, so as to
resist more powerfully the pressure of the fluid in the boiler or other vessel, and
the effect of unscrewing the nuts being on the contrary to relax the pressure of the
upper cross piece on the spring, and of the spring on the shoulder of the shaft
and on the disc. The screws, at the lower extremities of the legs of the frame or
bridge, must be made of sufficient length to permit the nuts to be screwed home on
them to such an extent as to produce any reasonable amount of pressure on the
spring which may be required.
The upper part of the spindle projects above the upper cross piece of the bridge,
and is, or may preferably be, furnished with a graduated scale to indicate the
pressure of the fluid or fluids within the boiler or other vessel and the variations in
that pressure from time to time. The greater the pressure in the boiler the further
or higher the upper part of the spindle will be forced up above the upper surface
of the upper cross piece of the bridge through which the spindle passes. The
upper surface of the upper cross piece is clean turned and made perfectly flat
and horizontal, so that the extent to which the spindle rises or falls through the
hole in the said upper cross piece may be easily determined by noting what
division of the scale marked on the spindle coincides in level with the upper
surface of the said upper cross piece. The scale may consist of horizontal lines
round the spindle at equal intervals, each interval indicating any increment or
decrement of pressure in pounds, and each line indicating any actual amount of
pressure within the boiler which it may be considered convenient to express and
distinguish. The scales used in different instruments may in all cases be uniform
in the width of the divisions or intervals which denote the same increment or
decrement of pressure, in which case the springs in all our instruments must be of
the same elasticity. Or if the springs in different instruments are of unequal
elasticity, the intervals of scale on such instrument will require to be specially
adjusted and marked on each instrument relatively to the elasticity of the particular
spring which forms part of it. The strength of the spring will require to bear a
proper proportion to the area of the disc, and the area of the disc will vary with
the boiler.
In using our safety valve the nuts which compress or relax the spring are
screwed up, so that the tension of the spring may balance any particular amount
of pressure in the boiler which may be selected as affording a good margin of
safety. When the pressure in the boiler rises above this point, the steam or other
fluid will raise the valve and escape against the rim and sides of the bell, thereby
giving an alarm or warning which will not cease till the pressure is diminished to
the safety limit to which the instrument has been set.
The whole parts of the instrument are preferably constructed of brass, but may
be of any other suitable metal or metals or material or materials.
It is evident that the different parts of our instrument are susceptible of con-
siderable alteration in form, but the essence of our Invention is to combine with a
safety valve, capable of being adjusted to any pressure inside a boiler or other
vessel in which an expansible fluid is being compressed, a whistle or other arrange-
ment which will, so soon and as long as the safety limit of pressure to which the
valve is adjusted or set is exceeded, give warning of the fact by emitting snorous
vibrations under the action of the fluid escaping through the valve.