Improvements in Safety Valves for Steam Boilers.
Year: 1892

page_text: COMPLETE SPECIFICATION.
Improvements in Safety Valves for Steam Boilers.
I, JOSEPH MERRYMAN COALE, residing at No. 1307 John Street, in the City
of Baltimore, State of Maryland, United States of America, Mechanical Engineer,
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 :—
My invention relates to safety valves, and the several features thereof are
applicable respectively to the classes known as pop valves and muffled safety valves,
and may be used to advantage in safety valves combining the features of both these
classes. My invention is designed to supply mechanism capable of adjustment with
great accuracy, and acting in combination with the pop valve, whereby when the
boiler pressure reaches the point at which the valve is set to blow off, and the valve
rises in consequence thereof, it shall close with equal promptness when the excess
of pressure has been relieved and the gauge has fallen to a point below which it is
not desirable to have the steam pressure recede; it therefore consists of the com-
bination with a pop valve and the external case, of a vertically adjustable valve
seat constructed as hereinafter described whereby the relative closing and opening
pressure of the valve can be adjusted with accuracy.
My invention also has for its object the steadying of the valve stem, and the
provision of means therefor which will not be affected by the great heat of the
steam passing over the same and entering the valve through the large induction
port at the base of the valve case and where it is attached to the boiler; and to
this end it consists of the mechanical means therefor hereinafter described.
My invention moreover relates to means for relieving the head of the valve from
any back pressure due to compression of air or the entrance of steam, in the spring
chamber, and it consists of two alternative forms, each comprising, in the combina-
tion a hollow valve-adjusting screw and the external shell or discharge casing ;
these parts being combined in one form, with a perforated chamber formed between
the interior surface of said shell and an annular flaring collar on the spring chamber,
and in the other alternative form the said parts are combined with a perforated
chamber formed in the closing cap which bears against the shell exteriorly and
carries a screw ring also bearing thereon and registering with the screw thread on
the periphery of the valve-adjusting hollow screw.
In the accompanying drawings,
Figure 1 is an elevation of a muffled safety valve embodying the several
features of my present invention; the drawing showing the external muffler case
removed.
Figure 2 is a vertical sectional view of the same the external muffler casing being
in place thereon.
Figure 3 is a vertical sectional view of an alternative form of closing cap; and
Figure 4 is an horizontal section thereof.
Figure 5 is a plan of the mechanical means for steadying the valve stem.
Figure 6 is a plan of my improved adjustable valve seat.
Figure 7 is a vertical sectional view through Figure 6; and,
Figure 8 is a vertical sectional view of a modification thereof.
The base A of the valve case is provided with screw threads a or other suitable
means, for attaching it to a boiler. It also comprises a central bearing a¹ for the
stem of the valve B, which seats upon an annular ground joint seat a². The
construction of said central bearing a forms one of the features of my present
invention, and will be fully described hereafter. Surrounding the annular valve
seat a is an annular wall at formed in the casing.

page_text: Internal screw threads are formed in the walls of the case and well for the
attachment of the threaded adjustable-ring valve-seat C hereinafter described and
the upper section A' of the valve case. This section is preferably-of-the-form
shown consisting of two cylindrical walls b' united at the top and an inverted
cup-shaped portion 6 rising concentric with the inner cylinder bi
The valve B is guided by the lower part of the cylinder as hereinafter
described. The part b¹ constitutes the spring chamber enclosing the spring c which
abuts at its upper end against a shoulder on the threaded hollow adjusting screw D
working in a threaded opening 6 in the upper end of the portion of the spring
cylinder. The lower end of the spring rests preferably on an annular shoulder of
the post E which is stepped in a central socket in the head or outer face of the
valve B.
A muffler dome or casing A2 is screwed upon the upper section A' of the valve
case, and a cap A* (in Figure 2) covers the upper end of the hollow screw D; said
cap being screwed down on the screw D until it abuts upon the upper end or
neck of the dome or casing A2, thereby forming a locked nut for the adjusting
screw D.
A series of perforations m are made in the upper part of the section b
of the valve case. The outer dome shell or case A2 is provided with a series of
like perforations n. Said perforations serve to muffle the escaping steam which
rises into the annular passage between the cylindrical walls bb and passing the
perforations m therein, and then laterally into a shell A' and thence radiates
through the perforations m in the same into the open air.
The steam is prevented from entering the spring chamber by means of the closely
fitting contacting surface of the upper portion of the valve B with the inner face
of the wall b¹ of the section A' of the casing. A packing ring may, however, be
inserted between said contacting surfaces in an annular groove as at r, if desired.
Should, however, any steam enter said spring chamber, and in order to allow free
outlet for such steam and also to prevent compression of air within said chamber
on the rising of the valve, the adjusting screw D is made hollow and slit at one or
two places as at d, in order to allow communication through the same with an
annular chamber N formed in the perforated top of the section A of the dome
or casing.
This chamber is formed by an annular extension of the wall of the inverted
cup-shaped portion of the valve case, said extension rising from the solid
portion surrounding the adjusting screw D and being substantially of the form of
an annular flaring collar 6, the edge of which is of such size relatively to the dome
shell or casing A as to abut against the inner face of the same when the parts are
assembled and held tightly together by being screwed down and thus constitutes a
dividing wall forming thereby an inner chamber N partitioned off from the main
portion of the dome shell A2, said chamber N being open to the atmosphere
through the inner row or series of perforations in the shell or cover A².
In the alternative form, shown in Figure 3, the annular collar on the spring
chamber is not made flaring but is perpendicular and affords a resisting surface to
support the pressure on the shell when the closing cap is screwed down on it, and
the slits d in the hollow adjusting screw D are omitted, said screw being left open
at both ends. The closing cap A³ is made of larger diameter at the base to form a
chamber N¹ between it and the top of the shell A² on which it rests.
Said cap is
provided thereat with an annular series of perforations n'. Communication between
said chamber N₁ and the hollow screw D is provided by means of passage ways w
formed by supporting the ring X' from the interior of the cap by means of arms s,
(see Figure 4). The said ring has a base of relatively larger diameter and rests
upon the neck n² of the shell or casing A2 and forms as in the other construction
described a locked nut for the adjusting screw D.
Another feature of my invention consists in the construction of the central
bearing a for the stem 6* of the valve B. Said bearing consists of a ring a
supported by arms a constructed integrally with a section of the shell. The
construction is shown in plan view in Figure 5 Sheet 2. And my present

page_text: improvement in that form of construction is the provision of dividing the ring-
bearing a into arc sections by cutting away parts of it at intervals between the
arms, as at a. The object of this being to allow for contraction and expansion of
the metal.
It has been found that with such a construction of bearing, made as heretofore,
the great heat of the steam playing directly upon it, causes contraction and
expansion, which takes it out of a true line and consequently it will not serve for
accurate guidance of the valve stem 6* which plays vertically in it. Much
difficulty has been heretofore experienced with valves provided with such guide
bearings due to this cause, as the valve will not seat properly. After repeated
experiments I have discovered that by making the guide-bearing ring a' in sections,
as shown in Figure 5, and thus allowing for contraction and expansion, no difficulty
whatever is experienced, and the guide allows perfect vertical reciprocation of the
valve stem *.
The last part of my present invention consists of the construction of the
vertically adjustable ring valve seat whereby the relative closing and opening
points of the valve can be adjusted with accuracy. Its two forms are shown in
Figs. 5 and 6. In safety valves heretofore constructed, it has been customary to
accomplish this adjusting result by making an outlet or outlets from the pop
chamber in the valve itself, and to provide some means for adjusting the size of
this outlet. In my present invention I make the outlets in the outer or supple-
mental valve seat, which is formed by an annular ring C and secure the adjustment
by the provision of means for vertically adjusting the latter.
In Fig. 2 is shown the form of adjusting ring shown in Figures 6 and 7. It is
screw-threaded on its exterior periphery as at 8, to fit in the screw threads a of
the section A¹ of the valve casing. It is provided on its top surface with an
annular series of perforations 9 extending downwards to an annular groove 10 on its
interior face. The outer rim of the pop chamber of the valve B rests upon the
upper face of the ring inside of the annular series of perforations 9 and the groove
with which these perforations connect communicates with the interior of the pop
chamber.
In the form of ring shown in Fig. 8 it is made in two parts m and m³, the
groove 10 being formed by the overhanging ledge 11 which groove is made wider
or narrower by screwing the part m upwards or downwards and separating it from
or bringing it closer to the part m which remain stationary. The valve B has a
central stem 6* sliding in the guide a'. It is provided with a flange B² projecting
horizontally beyond the face of the initial valve seat a' and serving to form with
the valve seat and the adjustable ring C (forming a second or supplemental valve
seat) the pop chamber x. The ring is exteriorly threaded at 8 to engage with
the screw threads a' in the section A of the casing. It extends across the annular
wall a and has an internal face fitting and sliding vertically on the outer surface
of that portion of the valve case A containing the valve seat a². The ring thus
practically shuts out the steam from the wall a*. In order to rotate the ring I
form on its periphery a series of gear teeth n, see Figure 6 constituting an annular
rack. By appropriate means, the ring C is turned in the case and is slowly
screwed up or down, as desired and the outer openings through the valve seat in
the pop chamber made greater or less as circumstances of adjustment may require
or be desirable.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. The combination with the pop chamber, of the valve annularly surrounding
the initial valve seat, and with the screw-threaded valve casing, of the mechanism
herein described consisting of the adjustable ring C having the parts 8, 9, 10 and 11,
for forming a supplemental valve seat and regulating and adjusting thereby the area

page_text: of the supplemental passage for the escape of steam from the pop chamber, substan-
tially as and for the purpose described.
2. The combination with the valve casing, the initial valve-seat formed thereon,
the supporting arms, and a guide bearing constructed in sections, of a valve adapted
to said valve seat, and having a stem adapted to be reciprocated vertically in said
guide bearing, substantially as described.
3. The combination with a valve casing, its valve, an interior spring casing
having an upwardly extended annular wall, a perforated external muffler chamber,
partitioned by said annular wall to form an interior chamber open to the air
through one or more series of said perforation and a hollow spring adjusting screw
passing through said interior chamber and provided with a recess opening into the
same; substantially as described.
4. The combination with an interior spring chamber, a valve adapted to rise
therein, a spring controlling said valve, an external casing or shell, a hollow spring-
adjusting screw passing through said valve chamber, and a closing cap provided on
its interior with radial arms & carrying a screw ring X adapted to operate as a lock
nut for the valve adjusting screw and having a base of relatively larger diameter
adapted to rest upon the exterior shell or casing, and provided with perforations n¹
cominunicating with the atmosphere, substantially as described.
Dated this 20th day of December 1899
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.