IMPROVEMENTS IN SAFETY VALVES
Year: 1884

page_text: PROVISIONAL
DIECIFICATION.
I, JOHN HENRY JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex
Gentleman do hereby declare the nature of said Invention for "IMPROVEMENTS IN
SAFETY VALVES" which Invention has been communicated to me from abroad by
Messieurs Lethnillier and Pinel of Rouen in the Republic of France Engineers to
be as follows:-
This Invention relates to improvements in safety valves of the class described in
the Specification to former Letters Patent granted to me and dated the 13th day of
July A.D. 1883 No 3474. The Safety Valves described in that Specification are
enclosed in a chamber open at the upper part and are connected to a disc or body
against which the escaping steam is caused to impinge and thereby aid in moving
the valve away from its seat These valves are especially suitable for Marine
Engines or other Engines so situated that the steam cannot be discharged directly
into the atmosphere and the chamber surrounding the safety valve requires to be
enclosed in an outer case provided with a suitable escape pipe.
When the improved valve is employed under these conditions the steam being
unable to expand freely, exercises a certain amount of downward or counter
pressure upon the upper disc or body connected to the valve and this pressure has
the effect of counteracting to a certain extent the action of the steam which lifts
the valve.
1
According to the present Invention this disadvantage is remedied by constructing
the chamber containing the valve in the manner hereinafter described. In place of
the annular opening formed above the valve disc as described in the Specification
of the Patent N° 347483 lateral openings are formed in the vertical sides of the
chamber enclosing the valve in such a manner as to enable the steam to escape
laterally into the outer case and thus prevent the steam from reacting upon the
disc or body above the valve.
By means of this arrangement the improved safety valves when enclosed in a
box or case are enabled to act with the same mathematical accuracy as when
discharging directly into the atmosphere.
These improved safety valves rise gradually in proportion to the pressure and
float as it were upon the steam and partake of every movement of the stream of
fluid.
The following is an arrangement of valve according to this Invention :-
The chamber containing and guiding the valve in place of being open at the
upper part is closed by the disc or body connected to the valve so that when the

page_text: valve opens the steam can only escape through a lateral orifice or orifices provided
in the sides of the said chamber.
The steam is thus caused to pass into the discharge pipe or passage without
exerting any counter pressure on the disc or body connected to the valve.
The valve is loaded by an adjustable spring fixed at its lower extremity in
a collar bolted to the valve case and secured at its upper extremity to a cap
provided with a screw which forms a bearing for a steel bar provided with a knife
edge This bar is connected at right angles to a small horizontal arm or lever and
forms a continuation of a vertical rod the lower end of which is pointed and bears
on the centre of the valve. The arm lever is pivotted at the top of an adjustable
bracket or support standing up from the case enclosing the valve.
This
The effect of this arrangement of the parts is that when the valve rises the
vertical rod is pushed up and acts through the bar upon the cap connected to the
spring causing the arm or lever connected to the bar to turn upon its centre.
movement of the lever causes the bar and the rod to incline to one side, the upper
extremity of the vertical rod being constrained to describe an are having the head
of the valve as the centre. The valve when lifted does not compress but extends
the spring.
According to another arrangement the steam is allowed to escape freely through
an annular orifice at the upper part of the chamber enclosing the valve but the disc
which is connected to and arranged over the valve is caused to overlap the sides of
the chamber and closes this annular orifice when the valve is down on its seat.
J. HENRY JOHNSON,
47, Lincoln's Inn Fields, W.C.,
Agent for Messieurs Lethnillier and Pinel.

page_text: "
I JOHN HENRY JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex
"IMPROVEMENTS IN
Gentleman do hereby declare the nature of said Invention for
SAFETY VALVES which Invention has been communicated to me from Abroad by
Messrs Lethinllier and Pinel of Rouen in the Republic of France Engineers 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 improvements in safety valves of the class described in
the Specification to former Letters Patent granted to me and dated the 13th day of
July A D 1883 N° 3474. The safety valves described in that Specification are
enclosed in a chamber open at the upper part and are connected to a disc or body
against which the escaping steam is caused to impinge and thereby aid in moving
the valve away from its seat. The said valves are specially suitable for marine
Engines or other Engines so situated that it is necessary that the steam should not
be discharged directly into the atmosphere and the chamber surrounding the safety
valve consequently requires to be enclosed in an outer case provided with a suitable
escape pipe.
When the aforesaid valves are employed under these conditions in a case or
chamber open at the upper part only the steam being unable to expand freely
exercises a certain amount of downward or counter pressure upon the upper dise or
body connected to the valve and this pressure has the effect of counteracting to a
certain extent the action of the steam in lifting the valve. The effect produced by
this counter pressure in thus preventing the valve from acting with its usual
mathematical accuracy proves the correctness of the principle of the original
Invention.
According to the present Invention the chamber containing the valve is con-
structed in the manner hereinafter described whereby the cause of the aforesaid
counter pressure is removed-In place of the annular opening formed above the
valve disc as described in the Specification of the aforesaid Patent No 347433
a lateral opening or lateral openings is or are formed in the sides of the chamber
enclosing the valve in such a manner as to enable the steam to escape laterally into
the outer case without reacting upon the disc or body above the valve.
Valves constructed according to the present Invention present the same leading
features in common with the valves constructed according to the aforesaid former
Invention in the respect that they are provided with a disc arranged above the
valve and a chamber in which the valve works but when applied to enclosed valves
the annular opening at the upper part of the chamber is dispensed with and in
place thereof the aforesaid lateral opening or openings is or are formed in the sides.
of the said chamber as hereinafter described.
By means of this arrangement the improved safety valves when enclosed in a.
box or case are enabled to act with the same mathematical accuracy as when
discharging directly into the atmosphere-These valves give the advantage of
admitting of a full lift of the valve disc the area or passage of the inlet and outlet
being equal to that of the valve.
The improved safety valve rises gradually in proportion to the pressure and
if it sometimes descends by fluctuation of pressure it merely returns to an extent,

page_text: corresponding to the variation of pressure, the said valve floating as it were upon the
steam and having a movement corresponding to every fluctuation in pressure of the
stream of fluid-These safety valves are operated automatically in the same manner
as the steam valve is operated by the hand of the engine driver on starting an
Engine being caused to open gradually and thereby enable a stream of fluid to be
established without any sudden shock.
And in order that the said Invention may be fully understood I shall now
proceed more particularly to describe the same and for that purpose shall refer to
the several figures on the annexed sheet of drawings the same letters of reference
indicating corresponding parts in all the figures.
Figure 1 of the accompanying drawings represents an elevation partly in section
and figure 2 a vertical section of a valve constructed according to this Invention
the said valve as shewn in Figure 2 being enclosed in a case and being loaded by a
direct acting compensated spring.
The valve disc or valve proper indicated at B figure 2 is surmounted by a disc
or body b against which the escaping steam impinges so as to aid in lifting the
valve which is enclosed in a chamber A which chamber in place of being open at
the upper part for the escape of steam is closed by the disc b so that when the
valve opens the steam can only escape through lateral orifices a¹ formed in the
vertical sides of the said chainber-The valve is supported laterally by guides a²
cast on the sides of the chamber and the disc b is fitted so as to slide in the upper
part of the said chamber-The steam from the interior of the chamber A passes
through the orifices a¹ into a passage D surrounding the said chamber without
exerting any counter pressure on the disc b and is delivered from the passage D
into a suitable outlet duct D¹ figure 2.
The valve is loaded by an adjustable spring R fixed at its lower extremity in a
collar E bolted to the valve case and is secured at its upper extremity to a cap F
provided with a screw f which forms a bearing for a steel bar g provided with a
knife edge or point g-This bar is connected at right angles to a horizontal lever L
and forms a jointed continuation of a vertical rod G the lower end of which is
pointed and bears on the centre of the valve-As indicated in Figure 1 the lever L
is pivotted at L' to the top of an adjustable bracket or support K standing up from
the case D.
The effect of this arrangement of the parts is that when the valve rises the rod G
is pushed up and acts through the bar g upon the cap F causing the lever L to turn
upon its centre L'-This movement of the lever causes the bar g at the end of the
rod G to be inclined the points of contact being shifted from x and y to x and y¹
figure 1-The rod G is also caused to incline to one side; its upper extremity being
constrained to describe an arc baving the head of the valve at its centre.
The object of this arrangement is to graduate the pressure upon the valve in such
a manner as to compensate for the decreasing lifting power of the steam resulting
from the wide opening of the outlet.
Figure 3 shows, partly in section and partly in elevation a view of another form
of valve according to this Invention combining the advantages of a valve dis-
charging directly into the atmosphere with those of a valve enclosed in a case.
According to this arrangement the steam is allowed to escape freely through
an annular orifice a¹ at the upper part of the chamber enclosing the valve but the
disc b which is arranged over the valve B is caused to overlap the sides of the
chamber A and closes this annular opening when the valve is down--This arrange-
ment is most suitable for small valves being more simple in construction than the.
one herein before described.
Having now particularly described and ascertained the nature of the said
Invention and in what manner the same is to be performed I declare that what
I claim is
'
1 In safety valves of the class hereinbefore mentioned the combination of
a lateral orifice or lateral orifices a¹ in the sides of the chamber enclosing the valve
disc the said valve being connected to or formed with a disc or body working in or

page_text: guided by the upper part of the said chamber and acted on by the escaping steam
so as to assist in lifting the valve substantially as herein before described and
illustrated in the accompanying drawings.
2nd In a safety valve constructed and operating as hereinbefore setforth and
claimed the combination of a spring acting by extension and provided with means
for regulating and equalising the force upon and movement of the valve in
correspondence to the varying pressure of the steam substantially as herein before
described and illustrated in figures 1 and 2 of the accompanying drawings.
3rd The safety valve constructed and operating substantially as herein before
described with reference to figure 3 of the accompanying drawings.