IMPROVEMENTS IN SAFETY VALVES
Year: 1880

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine, Lake,
& Co., Patent Agents, Southampton Buildings, London, for an Invention of
"IMPROVEMENTS IN SAFETY VALVES." A cominunication from abroad by
Henry George Ashton, of Somerville, Massachusetts, United States of America.
PROVISIONAL SPECIFICATION left by the said William Robert Lake at the
Office of the Commissioners of Patents on the 22nd September 1880.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "IMPROVEMENTS IN SAFETY VALVES." [A com-
munication from abroad by Henry George Ashton, of Somerville, Massachusetts,
United States of America.]
This Invention relates to improvements in the construction of safety valves, and
comprises a new mode of arranging the spring in safety valves, and also other
novelties in the construction of such valves.
One part of this Invention consists in placing the spring of the valve between
two supports, one of which is pivoted upon the centre of the valve and the other
upon the adjusting screw; so that each support is free to tilt as the spring may
require, and the whole pressure of the spring is exerted upon two pivots, both of
which aro in line with the axis of the valve, and the lower one of these pivots is
near the level of the ground joint or seat of the valvo.
Another part of this Invention consists in the combination with the shell or
outer casing of the valve of a cap or top plate through which the adjusting screw
passes; the shell contains the bushing, the valve proper, and the spring with its
two supports; the spring and both supports being above the valve seat, and each
support being free to tilt to suit the spring.
According to another part of this Invention I make the upper part of the shell
adjustable relatively to the valve which overhangs its seat, the overhanging
portion of the valve acting in connection with the adjustable shell to retard the
passage of the steam which has escaped past the seat of the valve, and thereby
assists in lifting the valve against the force of the spring.

page_text: According to one method of carrying my Invention into practice, I provide the
valve with a shell which is tapped at its lower end for connection with the boiler,
and at one side for connection with a pipe through which the wasto-stcam passes,
so that the waste steam may be discharged at a point at a distance from the said shell,
but I may allow the steam to escape directly into the air through one or more holes
in the aforesaid shell.
The lower part of this shell is bored out to receive a suitable bushing, which I
prefer to make of metal different to that from which the shell is made, as will be
well understood without further explanation. This bushing after being turned and
bored is forced into its place.
The upper surface of the shell is turned off in a lathe, and the upper inner portion
is bored true; the aforesaid bushing should be re-bored after it is in place in the
shell, as it is necessary that the axis of the bore of the shell and the axis of the
bushing should be in line, as even an apparently trifling deviation might produce a
bad effect.
I also provido a cap and a cylinder cast in one piece so that the axes of this
cap and cylinder shall be in line; and the cap is turned true at its shoulder and
accurately fitted to the mouth of the shell herein before described, so that when
in place the axis of the bushing and the bore of the shell, that of the said cap and
cylinder, shall all be in line.
▲ screw which serves as an adjusting screw passes through the centre of the cap,
so that its axis is in line with all the other axes. I further provide a valve proper
which is turned true, so that its guides will fit in the bushing and its upper part in
the cylinder aforesaid, and thereby the axis of the said valve when the same is on
its seat is brought in line with all the other axes. In the interior of the shell. I
arrange a coiled spring supported between two discs; the lower disc is pivotted
-directly-upon-the-centre-of-the-valve proper and the upper disc directly upon the
centre of the aforesaid adjusting screw. These discs can tilt freely upon their pivots
as the greator stiffness of the spring on one side than on the other may require.
The valve proper has already been described in the Specification of former
Letters Patent, No. 2049, A.D. 1878, and the present Invention relates to the
arrangement of the spring and to the combination of the shell, cap, valve, and
spring, and not to the particular form of valve and scat.
A suitable cover serves to prevent tampering with the adjusting screw and also
to provent the entrance of cinders, dust, and the like to the holes in the cap; the
flange of this cover may be perforated.
According to a modification of my Invention the valve proper is slightly conical,
and the upper part of the shell is made to screw upon the lower part, a suitable set
screw serving to keep the upper part of the shell from rising after it has been
adjusted.
The inner diameter of the adjustable part of said shell is at one portion of its
height only slightly greater than the larger diameter of the valve proper (say
about one-sixty-fourth part of an inch), but at a portion just above the last named
portion it is of considerably greater diameter than the valve.
According to this part of my Invention the cap plate is cast in one piece with
the shell, as this is a cheaper form of valve than that herein before specified; but
it may be made with an inner cylinder to protect the spring and to receive a
circular rim projecting upwards from the valve. A bushing like that above
described with reference to the first part of my Invention may be used, and a cover
like that also above described may be used with the safety valve constructed
according to this modification of my Invention, to prevent tampering with the
adjusting screw; small holes in the upper part of the shell are provided for the
purpose of allowing air and steam to escape freely from the upper part of the said
shell, and thereby prevent any pressure in the upper part thereof. These holes
need not be covered as they are on the side of the shell, so that cinders and the
like are not likely to enter them. The adjusting screw, the discs, and the spring
between the latter are substantially the same as those described with reference to

page_text: the first part of this Invention. The shell is so adjusted (by the variation in the
diameter of its parts) that the pressure tending to lift the valve proper is greater
after the valve las left its seat than before, and thereby the said valve-is caused to
rise suddenly and open sufficiently to relieve the boiler as soon as the pressure
in the boiler is sufficient to lift the valve slightly from its seat. Valves working
on this principle, that is, where the total effective pressure tending to lift the valve
against its spring is greater after the valve has left its seat than before, are too
well known to need description; and this part of my Invention consists in
attaining this result by means of an improved construction of the parts of the shell
and the valve proper, the latter being made to overhang its seat, as hereinbefore
set forth. One part of the shell, if arranged to overlap the periphery of the valve
proper (by turning the upper part of shell after loosening the set screw) will
obviously make the total effective pressure tending to lift the said valve against
its spring greater than if the said part of this shell did not overlap the periphery
of the valve proper as stated, and the amount of such pressure will vary with the
amount of overlap.
The amount of overlap necessary for the best results depends upon the pressure
at which the valve is designed to work, and also upon the accuracy of the fitting
of the valve proper and the parts of the shell adjoining it. As the forinor expands
more than the shell care should be taken to make the periphery of the said valve
of such a diameter that it will not be caused to bind the shell by expansion.
If the part of the shell adjoining the valve proper overlap the latter too much
the result will be that the said valve will not close until after the boiler pressure
is reduced several pounds below the pressure at which the valve opened; when
this is the case the upper part of this shell should be screwed a little further on to
the lower part, thereby reducing the overlap on the said valve. When properly
made and adjusted the valve will always risc at the moment when the pressure in
the boiler is at the point at which the valve is set to blow, and will rise suddenly
from its scat, relieve the boiler, and close before the boiler pressure is reduced one
pound below the point at which the valve opened. The steam which escapes
between the periphery of the valve proper and the part of the shell adjoining it
passes out of the said shell through one or more holes into the atmosphere, or a
single escape pipo may be used as set forth.
It is desirable, although not essential, to provide a suitable ring which will
prevent the bulk of the waste steam from entering the upper part of the shell.

page_text: The lower part of this shell A is bored out to receive the bushing B, which is
usually of a different metal from the shell A, as will be well understood without
further explanation. This bushing after being turned and bored is forced into its
place in the shell A.
The upper surface of the shell A is turned off in a lathe, and the upper inner
portion is bored true. The bushing B should be re-bored after it is in place in the
shell A, as it is necessary that the axis of the bore of the latter and the axis of the
bushing B shall be in line, as even an apparently trifling doviation will produce a
bad effect.
The cap C and the cylinder D are cast in one piece, so that the axes of the cap
and cylinder shall be in line, and the cap is turned truo at the shoulder c and
accurately fitted to the mouth of the shell A, so that when in place the axis of the
bushing B, the bore of the shell A, the cap C, and the cylinder D, shall each be in
line.
The screw F passes through the centre of the cap C, so that its axis is in line
with all the other axes mentioned.
The valve G is turned true, so that its guides will fit in the bushing and its
upper part in the cylinder D, and thereby the axis of the valve when on its seat
is brought in line with all the other axes mentioned.
The spring His supported between the discs h, h¹; .the lower disc h is pivotted
directly upon the centre of the valve G, and the upper disc h' directly upon the
centre of the adjusting screw F. These discs h, h¹, can tilt freely upon their pivots
as the greater stiffness of the spring on one side than on the other requires.
The valve G shown in the Drawings is similar to that described in the
Specification of former Letters Patent, dated May 22nd, A.D. 1878, No. 2049, and
the present Invention relates to the arrangement of the spring, and to the com-
bination of the shell, the cap, the valve, and the spring, and not to the particular
formn of valve and seat.
The cover J serves to prevent tampering with the adjusting screw F, and also
to prevent cinders, dust, and dirt from entering the holes in the cap C, the flange
of the cover being perforated as shewn in Figure 3.
In Figures 4, 5, and 6, the valve G shewn is also an old form of valve, but the upper
part of the shell A is made to screw upon the lower part, the set screw a serving
to keep the upper part of the shell A from rising after it has been adjusted.
The inner diameter of the adjustable part of the shell A at the part marked a¹
is but very little greater than the larger diameter of the valve G, say, about
one-sixty-fourth part of an inch, but at the part marked a³ it is of considerably
greater diameter than the said valve.
The cap-plate C is cast in one piece with the shell, as this is a cheaper form of
valve than that shewn in Figures 1, 2, and 3, but the said cap may be made with
an inner cylinder to protect the spring and to receive a circular rim projecting
upwards from the valve, as in Figure 1.
No separate bushing is shewn in Figure 4, but a bushing similar to that marked
B in Figure 1 may be used, and a cover like that marked J in Figure 1 may also
bo used with the safety valve shewn in Figures 4, 5, and 6, to prevent tampering
with the screw F; the small holes a³ in the upper part of the shell A in Figure 4
are for the purpose of allowing air and steam to escape freely from the upper part
of the shell A, and thereby prevent any pressure in the upper part of the same.
These holes need not be covered by a perforated cover, as in Figures 1, 2, and 3, as
they are on the side of the shell, so that cinders, dust, dirt, and the like, are not
likely to enter them. The screw F, the discs h, h', and the spring H, are practically
the same as the corresponding parts shewn in Figures 1 and 2.
The purpose of adjusting the part a¹ of the shell A with relation to the periphery
of the overhanging part of the valve G is to make the pressure tending to lift the
valve G greater after the valve has left its seat than before, and thereby cause the
valve to rise suddenly and open sufficiently to relieve the boiler as soon as the
pressure in the same is great enough to lift the valve slightly from its seat, Valves

page_text: working on this principle, that is to say, where the total effective pressure tending
to lift the valve against its spring is greater after the valve has left its seat than
before, are too well known to need description; and this part of my Invention
consists in attaining this end by means of the parts a¹ and a² of the shell A. and
the valve G made to overhang its seat. The part a' of the shell A, if arranged to
overlap the periphery of the valve G (by turning the upper part of the shell A
after loosening the set screw a) will obviously make the total effective pressure
tending to lift the valve G against its spring greater than if the part a¹ of the
shell A did not overlap the periphery of the valve G, and the amount of such
pressure will vary with the amount of overlap.
The amount of overlap necessary for the best results depends upon the pressure
at which the valve is designed to work, and also upon the nicety of fit between
the valve G and part al; as the said valve expands more than the part a¹ of the
shell A care should be taken to make the periphery of the valve G of such a
diameter that it will not be caused to bind in the part al by expansion.
If the part al overlaps the valve G too much the result will be that the said
valve will not close until after the boiler pressure is reduced several pounds below
the pressure at which the valve opened; when this is the case the upper part of
the shell A should be screwed a little farther on to the lower part of the shell A,
thereby making the overlap of the part a' on the valve G'a little less. When
properly made and adjusted the valve will always rise the moment the pressure in
the boiler is at the point at which the valve is set to blow, and will rise suddenly
from its seat, relieve the boiler, and close before the boiler pressure is reduced one
pound below the point at which the valve opened. The steam which escapes
-between the periphery of the valve G and the part a' of the shell A passes out of
the latter through one or more holes a into the atmosphere; or a single escape
pipo may be used when the waste steam is to be carried to any desired point. The
ring on the valve G-provents-all-but-a-small part of the waste steam from passing
into the shell-A-above the said ring.
When the holes a' are large or numerous and open to the atmosphere.it.is.of
little consequence whether the ring be used or not, although it is desirable in all
cases; but when the steam is not allowed to escape freely from the shell A the said
ringf should be used.
In the modification illustrated in Figures 7, 8, 9, and 10, 1 have shewn another
valvo, which is the same in substance as to many of its features as that shewn in
Figures 1, 2, and 3.
One feature of this form of valve is an adjustable cock connected with a chamber,
liereinafter described, the upward pressure upon the said valve when open being
regulated by the adjustment of this cock.
In all valves of this class the escaping steam passes first into the said chamber,
and the pressure of the steam in this chamber aids in lifting the valve against the
force of the spring, and as the area of the opening through which the steain enters
the said chamber is determined by the diameter of the valve scat and the height to
which the valvo rises, the pressure in the said chamber depends upon the boiler-
pressure and the area of the opening through which the steam escapes from this
chamber, as will be readily understood.
Moreover as the pressure required in the said chamber depends upon the increased
tension of the spring caused by the rising of the valve and the area of the surface
exposed to the pressure of the steam in this chamber, the proper area of the outlet
from the same depends upon the stiffness of the spring, the boiler pressure, the size
of the valve, and the area of the surface exposed to the pressure of the steam in the
said chamber; very great nicety and skill is therefore required to make these
valves so that they will work to good advantago at the desired pressure; and aftor
they are adjusted for that pressure it is difficult and often impossible to readjust
thein for a different pressure, especially when the second pressure is as much as one
third more or less than the first. But by this Invention I remedy this evil.
In the Drawing k represents the aforesaid chamber, m the inlet opening, and n

page_text: the outlet opening of the same; the stean escapes over the corner of the bushing
or sent B at m as soon as the boiler pressure is sufficient to start the valve G from
its seat, and this escaping steam enters the chamber and expands in the samo, its
pressure in the said chamber (supposing the cock L to be closed) depending upon
the area of the opening at m and the boiler pressure on the one hand and the area
of the opening at n on the other hand. When the lip of the valve at n is formod
to rest upon the upper surface of the seat B a number of small holes are formed
through the valve-lip, as shewn in the Drawing, the opening at n being insufficient,
and the total area of the outlet opening from the chamber being the area of the
opening at n added to the area of the holes ³.
It will be seen that I provide an additional opening 7 from the aforesaid chamber
and control this opening by the cock L. I can thus construct the valvo with the
outlet opening from the chamber much smaller than is requisite in practice, for
example, by reducing the number of the holes ³ or omitting them altogether, and
with the opening so large that the sum of the areas of the usual outlet openings
n, 3, (when those holes are used) and the additional outlet opening will be
abundantly large; then by adjusting the area of the additional outlet opening / the
valve can be adjusted readily and with the utmost accuracy after the valve is
applied to the boiler and while exposed to steam pressure.
When the chamber k is as small as in the valve shewn it is preferable to enlarge
it as shewn at k¹ for greater ease in attaching the cock L to the additional outlet
opening.
The preferable form of cock L is a hollow screw let in as shewn, so that the
hollow part of it is open to the aforesaid chamber; the hole can be brought to
coincide with the outlet when the additional outlet is required to be wide open,
or can be adjusted with relation to the said outlet as desired. The check nut
holds the screw L where set. The outlet 7 may lead into the open air instead of
into the case A as shewn.
I adapt my Invention to valves which are used where a large quantity of steam
is to be discharged through a pipe, leading from the case or cover of the valve, and
in particular for taking the steam from the boilers of a steain boat and discharging
it below the water line.
Heretofore the safety valves of steam-boats have discharged into the open air
with so great a noise as to be in the highest degree objectionable for many reasons.
I have arranged a safety valve of a large steamer by carrying its discharge pipe
down below the water line, and have discovered that that mode of discharging the
steam prevents all objectionable noise, the very great advantages of which will be
plain to all familiar with the navigation and management of steam-boats. I may
use any safety valve provided with a cover and a discharge pipe leading from that
cover to a point below the water line; but the pressure of steam in the valve cover
should always be kept from aiding the spring in closing the valve by keeping the
steam as far as possible from access to the upper surface of the valve, as above
explained; but the valve shewn in Figures 7, 8, 9, and 10 of the Drawing is well
adapted for this especial use, as it is not only an under-discharge valve, but is also
a double seated under discharge valve, that is to say, it has an annular valve, or
has two escape openings m and m¹ for the steam, and is provided with a head f
which fits in a cylindrical part of the case D so that the pressure of the
steam within the said case is prevented from aiding to force the valve back on its
seat.
In a steam boat valve a spindle h³ and lever h³ are desirable. The spindle h³ is
pivotted on the valve and is formed with a convex collar h at its lower end; by
this collar the disc h is supported, and the lower end of the valve spring H rests
upon this disc h; the upper end of the said valve spring H is pressed upon by the
disc h', which is pressed upon by the convex collar h³ on the nut h6, actuated by a
hollow screw h, through which the spindle h³ passes. The nut cannot turn in
the case D, but the screw can be turned, after loosening the check nut h³, to
increase or decrease the tension of the spring H.

page_text: Having thus fully described the said Invention as communicated to me by
my foreign correspondent, and the manner of performing the same, I wish it
understood that I claim,-
First. In a safety valve the spring supported between the two discs h, h¹, the
lower disc pivotted directly upon the centre of the valve and near the level of
the ground joint or valve seat, and the upper disc h' pivotted directly upon the
centre of the adjusting-screw, both discs being free to tilt as the spring requires,
all as and for the purpose set forth.
Second. The combination of the shell, the bushing, the cap, the screw F, the
spring, the discs h, h', and the valve G, the screw F passing directly through the said
cap and the spring, and both pivots being above the level of the ground joint, and
all of the said parts being constructed and arranged substantially as herein described
and for the purposes specified.
Third. The combination of the valve G, having a portion which extends beyond
the ground joint, and the adjustable shell A, baving its inner diameter at a smaller
than at a², the overhanging part of the valve fitting the shell at a', substantially as
above set forth and for the purposes specified.
Fourth. The combination of the adjustable shell A, the valve C, and the ring f,
constructed and arranged substantially as above described and for the purposes
specified.
Fifth. The modification of my Invention, whereby I provide the safety valve
with the additional outlet from the chamber k, k³, controlled by the cock L,
substantially as and for the purpose set forth.
Sixth. Adapting my Invention to the safety valve of a steam boat, in combination
with a cover, to confine the escaping steam and a pipe leading from the said cover,
and passing through the steam boat below the water-linc, substantially as and for
the purposes described..
-Seventh. The modification of my Invention, wherein-1-combine_the_annular_
valve G and bushing B, arranged as shewn-to-form-two-openings m, m², for the
escape of the steam, the head f, and the case A, D, the head ƒ fitting the part D of
the case, and being connected with the valve G to prevent the passage of the steam
through the opening m' into the case D, substantially as described.
Eighth. The modification of my improved safety valve, wherein the spindle ² is
pivotted upon the valve and has a collar h, in combination with the disc h, the
spring H, the disc h³, the collar h, the nut h, and the screw h³, all substantially
as described and for the purpose set forth.
In witness whereof, I, the said William Robert Lake, have hereunto set my
hand and seal, this Twenty second day of March, in the year of our Lord
One thousand eight hundred and eighty one.
WM RORT LAKE (10)