Year: 1887

page_text: Date of Application, 31st Mar., 1887.
Specification Accepted, 6th May, 1887.
I WILLIAM ROBERTSON of the Seville Iron Works, Spencer Avenue, Dublin,
Mechanical 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 has reference to an Improved combined spring unit test valve, and
pressure gauge for the purpose of indicating with practical accuracy the pressure of
steam, or other liquid, or gaseous pressure.
The nature, and construction, of the Invention will be readily understood on
reference to the accompanying Drawings: Fig. 1 is an elevation, and Fig. 2 a vertical
section of the complete Apparatus; Fig: 3 is a detail view hereinafter referred to.
Similar letters indicate corresponding parts in each of the views.
The centre pipe a, communicates direct with the boiler and in the seat or chamber b,
rests the valve c, which is calculated to present a superficial area equivalent to one
square inch.
This valve is pierced by an aperture of suitable area through which the steam passes
to an ordinary pressure gauge mounted on the top of the hollow spindle d, which
gange indicates the pressure under the valve independently of the spring test, as
hereinafter described."
On the vertical spindle d, is pivoted the cross bar e, by means of two steel
rollers (fig. 3) carried on set screws ff", riding on a collar g, round valve
spindle, which arrangement admits of a slight oscillation in the cross bar, as well as
the rotation of the spindle so as to enable the gauge to be turned in any direction, and
the valve also to be turned round, and round, to see if free.
The free ends of the cross bar einbrace the vertical screws. h, which are coupled
to two spiral springs i. i, of the ordinary spring balance kind which latter are in turn
fixed loosely to the cross bar e¹, forming the base of the apparatus.
The edges of the balances are graduated to a scale of half pounds, according to the
strength of the springs. The free ends of the vertical screws h. h, are provided with
milled nuts k. k, by screwing down which, the pressure is increased on the valve
the extent at which it is desired to adjust the apparatus. In the front of the valve
chamber is inserted a plain, or a whistling blow off down pipe l, while to the rear is
C, to

page_text: attached a second blow off pipe p, whereby a current of air is free to pass through the
valve chamber.
A small taps, is provided at the base of the apparatus to allow condensed steam to
be drawn off and see that it is clear.
The action of my Invention may be briefly described thus. Having first ascertained
the weight of the superstructure mounted on the valve, the scales on the sliding
sleeves of the balances are carefully graduated, according to the expanding force of
the springs.
The Apparatus is screwed on to the boiler, or to a pipe from boiler, by a nozzle at the
rear of the pipe a.
Should it then, for example be desired to indicate steam at say 80 lbs. pressure, the
milled nuts are screwed so as to pull or stretch the springs until the sliding sleeves
are raised sufficiently to bring the unit 80 under the index pointers. There will then
be a pulling force of 80 lbs. exerted, on the cross bar e, and consequently on the valve.
While the apparatus stands thus adjusted it will mechanically indicate a pressure of
80 lbs. on the valve but should this limit be exceeded, the valve will be instantly lifted,
and the steam will escape.
Simultaneously with the indications of the springs, the ordinary gauge at the top of
the apparatus is acted upon by the steam (passing through the hollow spindle)
independently of the action of the springs, so that should the spring arrangement fail
to act, the gauge will indicate and vice versa, while so long as the apparatus is in
perfect working order, the springs and the gauge should correspond in indicating, the
pressure for which the Apparatus is adjusted, thus one record acts as a check on the
other.
By the use of this Invention therefore, a means is afforded of indicating in a
practically unerring manner, the pressure of steam in a boiler to which it is applied.
It is obvious that my Invention can be constructed to indicate the pressure. of
steam to any extent, springs being used varying in strength according to the pressure
to be indicated.
The graduations on the springs in the accompanying Drawings, show that pressure
up to 180 lbs., can be indicated; a pull of 90 lbs. on each spring representing, of
course 180 lbs. in the aggregate.
Having now particularly described and ascertained the nature of my said Invention
and in what manner the same is to be performed I declare that what I claim is,
1st. The use and application of a double spring unit test valve, constructed,
arranged, and operating, substantially in the manner, and for the purpose, herein
described.
2nd. In Apparatus for use and application to boilers, the combination formed by
the ordinary Pressure Gauge and the double spring unit test valve, substantially in
the manner, and for the purpose, herein described and set forth.
ሰለ 1
1
J. K. FAHIE & SON,
10, Leinster Street, Dublin,
Agents for Applicant.