Year: 1888

page_text: WO WALTER JOSEPH BOSLLY and WILLIAM WALLACE DICKSON of 78 Queen's
Rond Reading, in the County of Berks, Engineers, do hereby declare the nature of
this invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement
-
This invention is designed to supply an effective automatic safety-valve for Steam
Boilers, which can be regulated to blow off Steam at any pressure desired
The valve consists of a chest or chamber cast or otherwise, made, by preference
cylindrical in shape, the inside being nicely bored or fitted to receive a steam tight
piston, and an accurately fitted piston working therein, mounted on a piston rod
passing through a bearing in a guide bar at the inner or boiler end of the valve chest,
which communicates by openings with the boiler
Beyond the outer side of the piston is a coiled spring nearly the size of the interior
of the valve chest, at the outer end of this spring is a metalic or other disc also nearly
the size of the valve chest This second disc serves as a pressure plate to sustain the
coiled spring in its resistance to the piston It is worked forward and backward by
the piston rod or by separate rod upon which it is held by collars forming a swivel
support or in any other convenient way The piston rod or separate rod, has a thread
cut on its outer end, which engages with a nut in the outer end of the valve chest, so
that by turning the outer end of the rod, the disc can be adjusted as required,
whereby, and by incans of slots cut in the cylinder, the sud piston can be regulated
to blow off ste im at any pressure desired The slots referred to are three in all, two
of which are cut partly through the case of the chest, and have openings at their
outer ends forming steam outlets, while the third which is shorter is cut through the
case, and serves also as a guide for the index finger attached to the outer disc
finger indicates on a scale on the outside of the cylinder, the pressure at which the
piston is adjusted to blow off steam
This
The action of our improved piston valve is so simple as scarcely to need explanation
The steam pressure holds the piston tightly against the coiled spring, and when the
pressure of steam exceeds the limit considered desirable it forces the piston beyond
the slots, and so opens the valve, and allows the steam a free discharge Similarly

page_text: when the pressure of steam is reduced to the limit of safety, the spring closes the
valve automatically
In the accompanying drawings-
Fig 1 shows a sectional elevation of the piston valve
Fig 2 shews an exterior elevation thereof with the pressure scale
A 19 the valve chest
B is the spring
C is the piston
D is the pressure disc
Z is the piston rod
EE are steam inlets
FF are channels forming steam outlets
G is the screw and wheel for regulating the resistance
His the scale denoting pressure
I is the index finger
S is the slot in which the finger I works
Having now particularly described and ascertained the nature of our sud Inven-
tion and in what manner the same is to be performed we declare that what we
claim is
In an automatic safety valve for steam boilers the combination of a cylindrical or
other chest, with the steam tight piston C the piston rod Z and separate rod with
screwed end and nut the coiled spring B, the pressure disc D, with the index finger I
and the scale H substantially as herein explained and set forth
Dated this 12th day of June 1888