IMPROVEMENTS IN SAFETY VALVES
Year: 1884

page_text: "
I HENRY HARRIS LAKE, of the firm of Haseltine, Lake, and Co, Patent Agents,
Southampton Buildings, in the County of Middlesex do hereby declare the nature
of my invention for IMPROVEMENTS IN SAFETY VALVES" and in what manner
the same is to be performed, to be particularly described and ascertained in
and by the following statement :-
This invention relates to safety valves and has for its object to provide a safety
valve adapted to respond quickly to variations in the pressure of the steam, and to
close promptly when said pressure has been sufficiently decreased by the opening
of the valve.
The said invention consists in providing the valve proper with a perforated
plate, hereinafter termed the register, adapted to be operated by the pressure of
the escaping steam after the valve is raised, and thereby open passages through
the valve for the escaping steam, thus causing the pressure to be rapidly reduced
and enabling the valve to be readily closed by its spring in consequence of the
comparatively small area exposed to the steam pressure. The register is shut off
from the steam pressure when the valve is closed, and is provided with a spring
whereby it is partially closed after being thus shut off from the steam pressure, all
as hereinafter described.
In the accompanying drawing
Figure 1 represents a longitudinal vertical section of a safety valve embodying
my invention.
Figure 2 represents a top view of the valve showing its register partly closed.
Figure 3 is a similar view showing the register fully opened.
Figures 4 and 5 are sections on the lines x x and y, y Figures 2 and 3
respectively.
•
Similar letters of reference indicate corresponding parts in the several figures.
a indicates the valve casing or shell having the valve sent a¹ and being adapted
to be screwed at its lower end into the dome cover of a boiler.
b indicates the valve, provided with a stem b¹ and a spring c which forces the
valve against its seat as usual in valves of this class, the spring in this instance
being interposed between a collar, rigidly attached to, the valve stem, and an
adjustable collar which bears against a tubular adjusting screw, screwed into a
threaded socket in the upper portion of the shell, and regulates the pressure of the
spring.
The valve is provided with a series of orifices o extending vertically, or
substantially at right angles with the under surface, and has upon its upper
surface the perforated plate or register. The said register is adapted to rotate to a
limited extent on the said upper surface of the valve which forms a seat, its rotary

page_text: movements being limited by a stop pin 4 on the valve which enters a recess 5 in
the periphery of the register. The register is provided with a series of orifices o¹
which are adapted to coincide with the orifices o, and are formed diagonally or
obliquely as shown in Figures 4 and 5. A spring i secured at one end to the
register and at the other end to a collar j rigidly attached to the valve stem,
holds the register normally in the position shown in Figures 2 and 4, the orifices
in the valve being partially.covered by the metal between the orifices in the
register so that the inclined surfaces of the orifices o¹ are exposed to the action of
steam passing upwardly through the orifices o as shown in Figure 2.
When the valve is upon its seat, steam from the boiler cannot enter the orifices o
as the channel with which the holes o communicate is closed upon both sides by
the valve-seat, as shown in Figure 1.
When the valve is raised by the steam pressure, the escaping steam passes
through the orifices o and impinges against the inclined walls of the orifices o¹.
The pressure exerted upon the said walls causes the register to rotate so as to
cause the orifices o¹ to more nearly coincide with the orifices o as shown in
Figures 3 and 5. The passages through the valve are thus enlarged and allow
the steam to escape more freely than would otherwise be the case, while the area
of the valve against which the steam can act to support the valve is correspondingly
reduced. These two causes viz:-the increased area for the escape of steam and.
the decreased area of resistance to the upward pressure of the steam enable the
valve to close quickly when the boiler pressure falls to a predetermined degree.
There is therefore no liability of waste of steam such as is caused in many safety
valves by the failure of the valve to close when the pressure is sufficiently reduced.
When the valve closes, the spring i restores the register to the position shown in
Figures 2 and 4.
-
The concavity or groove n, with which the orifices o communicate, when tho
valve rises, affords an increased area on the under surface of the valve, enabling
the steam to support the valve more effectively.
The orifices o in the valve, and the register with its oblique orifices, constitute
what may be termed an automatic register.
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 :-
-
First. A perforated safety-valve provided with an automatic register which is
also perforated and adapted to partially close the openings in the valve when the
latter is sealed, and to be opened by the escaping steam when the valve is raised,
as set forth.
Second. A safety-valve having steam passages arranged to be closed by the
valve-seat when the valve is seated, and provided with a self-closing register
adapted to be opened by the escaping steam when the valve is raised, as set forth.
Third. In a safety-valve, the combination of the valve having orifices o adapted
to be covered by the valve seat, the annular rotary register having oblique
orifices o' adapted to coincide with the orifices o, a stop adapted to limit the rotary
movements of the register, and a spring whereby the register is restored to its
normal position after being displaced by the escaping steam, as set forth.
Fourth. A perforated safety-valve having an automatic register as described and
an annular concavity n in its lower surface, as set forth.