Improvements in Safety Valves for Steam Boilers.
Year: 1892

page_text: Date of Application, 19th Nov., 1892
Complete Specification Left, 18th Aug., 1893-Accepted, 7th Oct., 1893
PROVISIONAL SPECIFICATION.
Improvements in Safety Valves for Steam Boilers.
We JAMES ASHTON FLETCHER, and SAMUEL FLETCHER, both of the Borough
Brass Works, Ashton-under-Lyne in the County of Lancaster, Brassfounders, do
hereby declare the nature of this invention to be as follows:-
Our said invention relates to improvements in the construction of safety valves
of the type commonly known as Hopkinson safety valves which are used in connection
with steam boilers to permit the steam to escape in the event of the steam pressure
rising or in the event of the level of the water in the boiler descending below
certain predetermined points.
In one form of such valves the special valve for permitting the escape of steam
when the water falls too low (hereinafter referred to as the low water valve) is
combined with the valve for permitting the escape, of steam when the pressure rises
too high (hereinafter referred to as the high steam valve) the said combination
being effected by arranging the low water valve centrally in an annular high steam
valve. The total resistance to the escape of steam is in this case made up of the
sum of the separate loads on the low water valve and on the high steam valve.
When it is desired to lift the high steam valve for examination or for testing its
efficiency it is therefore necessary to lift the entire load of both valves simultaneously.
As heretofore constructed it has not been possible to raise the low water valve
independently of the high steam valve for the purpose of testing. With the high
pressures of steam now coming into use the total load on the combined valve is so
great that considerable force is necessary to enable the valve to be lifted for
testing.
The object of one part of our said invention is to obviate this disadvantage by
providing means preferably consisting of an excentric operated by a lever or hand
wheel for raising the central low water valve independently of the outer annular
high steam valve. We may however employ other devices such as sliding wedges,
screws or levers for the same purpose.
In some cases we arrange the lifting device so as to hold down the outer high
steam valve while the inner low water valve is being raised. When the inner low
water valve with its own load is lifted in this manner the outer high steam valve
with its own load may be more easily lifted for testing.
According to another part of our said invention which is applicable to the
construction in which the low water and high steam valves are independent of each
other we substitute for the internal load on the low water valve an external load
and provide means for raising the valve for testing similar to those hereinbefore
described with reference to the combined valve.
The load on the valves may be obtained by weights and levers, dead or direct
weights, or springs.
The levers and other means for connecting the floats or weights with the valves
are suitably modified to suit the improvements in the construction of the valves.
Dated this 17th day of November 1892.
E. T. WHITELOW,
70, Deansgate, Manchester, Agent for the Applicants.

page_text: COMPLETE SPECIFICATION.
Improvements in Safety Valves for Steam Boilers.
We JAMES ASHTON FLETCHER, and SAMUEL FLETCHER, both of the Borough
Brass Works, Ashton-under-Lyne in the County of Lancaster, Brass Founders, 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 and accompanying drawings to which reference is hereinafter made :-
Our said invention relates to improvements in the construction of safety valves
of the type commonly known as Hopkinson safety valves which are used in
connection with steam boilers to permit the steam to escape in the event of the
steam pressure rising or in the event of the level of the water in the boiler descending
below certain pre-determined points.
In-one form of such valves as illustrated in Figure 1 the special valve 6 for
permitting the escape of steam when the water falls too low (hereinafter referred
to as the low water valve) is combined with the valve a for permitting the escape
of steam when the pressure rises too high (hereinafter referred to as the high steam
valve). The combination of the two valves is in such case effected by arranging
the low water valve b centrally in an annular high steam valve. The total
resistance to the escape of steam is in this case made up of the sum of the separate
loads on the low water valve b and on the high steam valve a.
As such valves have heretofore been constructed when it has been desirable to
lift the high steam valve for examination or for testing its efficiency it has been
necessary to lift the entire load of both valves simultaneously. With the high
pressures of steam now being more largely used. and the consequent heavy loads on
the valves the total load on the combined valve is so great that considerable force
is necessary to enable the valve to be lifted for testing.
According to one part of our said invention we so construct and combine the
valves that by suitable means the low water valve & may be lifted independently of
the high steam valve a. When the former has been lifted the latter may be lifted
more easily for testing. The low water valve is mounted on a cross shaft c
resting in side bearings c'. The central part of the shaft at which passes through
the valve b is formed excentrically to the part which rests in the side bearings 80
that by rotating the shaft in the bearings the valve b may be lifted clear of the
valve a.
The latter with its own load may then be more easily lifted. The valve b
and the side bearings c¹ are shown in side elevation to a larger scale in Figures 1ª
and 1B respectively. In some cases two sets of excentrics may be formed on the
shaft c set opposite to each other so arranged that one may set bear down on the
valve a and hold it down while the other set bears upwards and lifts the valve b.
Another part of our said invention relates to that construction of valves in which
the low water and high steam valve are independent of each other as shown in
Figure 2. According to this part of our said invention we substitute for part or
all of the internal load of the low water valve an external load d which may be
obtained by means of one or more springs (adjustable in the usual manner) or by
means of weights and levers or direct weights. We in this case combine with the
spindle of the low water valve 61 and with the spindle of the high steam valve a¹
separate excentric lifting devices similar to those hereinbefore described with
reference to Figure 1. In this application the cross shaft is somewhat modified
being divided and the inner excentric ends thereof taking into annular grooves or
recesses (as shown in section at f Figure 2) in the valve spindle itself or in a sleeve
mounted thereon. The outer ends of the excentric shaft are in this case combined
with a stirrup or handle g. By simply pulling or pushing over the said stirrups
the valves may be readily raised from their seatings for testing.

page_text: Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is
1. A combined safety low water and safety steam valve so constructed that the
low water valve with its load may be lifted independently of the steam valve
substantially as hereinbefore described and set forth with reference to Figure 1 of
the accompanying drawings.
2. The combination of an excentric shaft a safety low water valve and side
bearings substantially as and for the purpose hereinbefore described and set forth
with reference to Figure 1 of the accompanying drawings.
3. The combination of a safety low water valve wholly or partially loaded ou the
outside with an excentric for raising the same substantially as hereinbefore described
with reference to Figure 2 of the accompanying drawings.
4. A divided excentric shaft taking into recesses in a safety valve spindle and
operated by a stirrup for lifting purposes substantially as herein before set forth and
shown in Figure 2 of the accompanying drawings.
Dated this 16th day of August 1893.
EDWARD TURNER WHITELOW,
70, Deansgate, Manchester, Agent for the Applicants.