AN IMPROVED SAFETY VALVE FOR STEAM BOILERS
Year: 1873

page_text: LETTERS PATENT to George Allibon and Alexandre Manbré, of
No. 19, Salisbury Street, Adelphi, London, for the Invention of
"AN IMPROVED SAFETY VALVE FOR STEAM BOILERS."
Scaled the 24th June 1873, and dated the 1st January 1873.

page_text: itself; instead also of employing a lever (whether such lever be straight
or curved) with a lesser weight on the outer end thereof proportioned to
the length or leverage thereof; and, instead also of using or employing
a spiral or other form of spring for giving the required amount of
counterpressure or load upon the valve, we construct a safety valve in the
following manner :-We prefer to employ for the body of the apparatus
a casting consisting of two chambers, in the one is the valve seat in which
the valve is fitted, and in the other is a gland or a stuffing box within
which a weighty or a hollow loaded piston of a suitable area and weight
is fitted so as to work freely and move up and down steam-tight therein.
These two chambers are connected together by a passage by which the
steam pressure within the boiler, when acting on the under side of the
safety valve, is also free to act and acts upon the upper side of the
loaded piston in the upper chamber. The under side of this chambered
apparatus has an opening for the passage of the steam from the boiler or
generator (or other vessel), upon which it may be mounted in any con-
venient position, and in any suitable manner. Whilst the valve remains
in its seat the steam is retained within the chambers and connecting
passage, and does not escape therefrom. The loaded piston is mounted
upon and is securely fitted to the upper end of the spindle of the safety
valve or to the pressure pin which bears upon the valve to hold or retain
it in its seat against the steam pressure within the boiler. By preference
the piston, upon the upper end of which the steam (or other pressure)
acts, may be formed of a mass of metal, or be a hollow cylinder containing
several pieces of metal of the correct weight, according to the intended
working steam pressure, but the piston itself or the hollow piston, and its
contained detached weights need not of necessity be of the weight required
for regulating the working pressure at which the valve of the boiler or other
vessel is to open and allow of the steam (or other contained fluid under
pressure) escaping when its force exceeds the assigned limit of pressure,
as the weight or load may be a separate body, or series of lesser weights
fitted upon the valve spindle or rod (or the pressure pin of the valve)
between the two chambers to which the weight or weights may be secured
under lock. The valve spindle should be guided in its length so as to
insure its moving up and down truly and freely. The area of the solid
piston exposed to the boiler pressure is smaller than that of the valve.
Its weight and the areas of the valve and piston respectively are cal-
culated upon a differential scale, according to the working pressure

page_text: intended to be employed, allowance being made for the friction of the
piston and its spindle.
When the pressure of the steam or other fluid within the boiler (or
other vessel) exceeds the resistance offered by the combined weight and
difference of pressure due to the reduced area of the piston in the upper
chamber the valve in the lower chamber opens, and the steam is
discharged into the "blow-off pipe," which should be connected with
and open from that portion of the lower chamber which is above the
valve seat.
By removing the cover plate on the top of the upper chamber the
weighted piston and the spindle may be withdrawn therefrom, and then
by removing the cover plate from the upper side or top of the lower
chamber the valve may be withdrawn from its seat.
The distance between the under side of the upper chamber and the
upper side of the lower chamber may be varied according to convenience,
and the space between the upper end of the piston and the inside of the
top cover of the upper chamber may be about one-fourth of the diameter
of the valve to permit of sufficient lift to allow of a "free blow off."
A lever may (if it be desired) be jointed to or connected with the
valve spindle at some exposed portion thereof. A "Bourdon" or other
pressure guage may be applied to the cover plate, or any other convenient
portion of the apparatus. A small passage should be made, and a drain
cock should be applied to draw off any water (or condensed steam) that
may collect above the valve or in the chamber between the top of the
valve and the blow-off passage.
Two or more safety valves with their pistons, as described, may be
combined within the same chambered casting, and one opening to the
boiler, and one "blow-off pipe " may be used in common for the passage
of steam to and from the several valves.
In consequence of the Board of Trade regulation by which steam
safety and blow-off valves of large area are required, so as to prevent the
rapid accumulation of volume and pressure of steam within the boiler or
steam generator beyond the load per square inch at which the free escape
of steam from the boiler is intended to take place, the use of dead weights
for loading the safety valves of high-pressure boilers becomes imprac-
ticable in sea-going ships, whilst the condition and accuracy of spiral

page_text: "
and other springs cannot be relied upon with sufficient certainty. In
these differential safety valves the very small dead weight or load
required upon the valve may be regulated in its amount by the limit of
the intended working pressure of steam in pounds per square inch
which it may conveniently equal in pounds dead weight, as it has only
to operate against and to represent the pressure upon the difference
between the areas of the valve and the piston.
The "differential safety valve" may of course be applied to other
objects than steam boilers or steam generators, and to other purposes
than regulating the discharge of steam under pressure from boilers or
generators, and the counterweights or dead load upon the valve may
be changed or reduced to admit of the boiler being worked at a lower
pressure.
SPECIFICATION in pursuance of the conditions of the Letters Patent
filed by the said George Allibon and Alexandre Manbré in the
Great Scal Patent Office on the 30th June 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, GEORGE
ALLIBON and ALEXANDRE MANBRE, of 19, Salisbury Street, Adelphi,
London, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the First day of January, in the year
of our Lord One thousand eight hundred and seventy-three, in the
year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto us, the said George Allibon and Alexandre Manbre,
Her special licence that we, the said George Allibon and Alexandre
Manbre, our executors, administrators, and assigns, or such others as
we, the said George Allibon and Alexandre Manbre, our executors,
administrators, and assigns, should at any time agree with, and no
others, from time to time and at all times thereafter during the term
therein expressed, should and lawfully might make, use, exercise,
and vend, within the United Kingdom of Great Britain and Ireland,
the Channel Islands, and Isle of Man, an Invention for "AN IMPROVED
SAFETY VALVE FOR STEAM BOILERS," upon the condition (amongst others)
that we, the said George Allibon and Alexandre Manbre, our executors

page_text: or administrators, by an instrument in writing under our, or their, or one
of their hands and seals, should particularly describe and ascertain the
nature of the said Invention, and in what manner the same was to be
performed, and cause the same to be filed in the Great Seal Patent
Office within six calendar months next and immediately after the date
of the said Letters Patent.
NOW KNOW YE, that we, the said George Allibon and Alexandre
Manbre, do hereby declare the nature of our said Invention, and in
what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement and the accom-
panying two Sheets of Drawings" :-
Instead of employing a dead load of weights upon the safety valve
or its spindle, equal in the number of pounds to the desired pressure
per square inch at which the valve is to lift, multiplied by the area
of the valve itself; instead also of employing a lever (whether such
lever be straight or curved) with a lesser weight on the outer or
overhanging end proportioned to the length or leverage thereof; and
instead also of using or employing a spiral or other form of spring for
giving the required amount of counterpressure or load upon the valve,
we construct a safety valve in the following manner:-We prefer to
employ for the body of the apparatus a casting consisting of two
chambers, but the two chambers may be separate castings and be con-
nected together; in the one chamber is the valve seat in which the
valve is fitted, and in the other chamber is a gland or a stuffing box
within which a weighty or a hollow loaded piston of a suitable area and
weight is fitted so as to work freely and move up and down steam-tight
therein. These two chambers may be connected together by a passage
or pipe, or by two pipes or tubes by which the steam pressure within the
boiler when acting on the under side of the safety valve is also free to
act, and acts upon the upper side of the
chamber. The under side of the lower
apparatus or the lower of the two portions
the passage of the steam from the boiler or generator (or other vessel),
upon which it may be mounted in any convenient position and in any
suitable manner.
Whilst the valve remains in its seat the steam is
retained within the chambers and the connecting passage or pipes between
them, and does not escape therefrom. The loaded piston is mounted
loaded piston in the upper
portion of the chambered
thereof has an opening for

page_text: upon and is securely fitted to the upper end of the spindle of the safety
valve, or to the pressure pin which bears upon the valve to hold or retain
it in its seat against the steam pressure within the boiler. By preference
too the piston upon the upper end of which the steam (or other pressure)
acts may in some cases be formed of a mass of metal, or it may be a
hollow cylinder open at the top and made to contain several pieces of metal
of the correct weight, according to the intended working steam pressure,
but the piston itself (or the hollow piston and its contained detached
weights together) need not of necessity be of the weight required for
regulating the working pressure at which the valve of the boiler (or
other vessel) is to open and allow of the steam (or other contained fluid
under prssure) escaping when its force exceeds the assigned limit of
pressure, as, for example, the weight or load may be the piston itself or
be a separate body, or a series of lesser weights may be fitted upon the
valve spindle or rod (or the pressure pin of the valve) between the two
chambers, and to which rod or spindle the weight or weights may if
desired be secured under lock. The valve spindle should be guided in
its length so as to insure its moving up and down truly and freely, or
with a minimum of friction. The area of the solid or other piston or
disc exposed to the boiler pressure must in every case be smaller than
that of the safety or escape valve. Its weight, and the areas of the
valve and piston respectively are calculated upon a differential scale,
according to the working pressure intended to be employed, allowance
being made therein for the friction of the piston and its spindle, as may
be determined by testing.
In some cases, and more particularly where the required rise of the
valve is not great we may interpose between the upper end of the piston
or disc and the steam pressing thereupon in the upper chamber a
corrugated or other suitable form of flexible diaphragm secured between
the flanges, or in any other suitable manner by which the full force of
the steam can be brought to bear effectively upon the entire area of the
piston or disc, and so to act upon the safety or escape valve.
In other cases instead of the piston or disc working in the cylinder of
the upper chamber with metallic or other packing (and its attendant
friction), we use or employ an inverted vessel or cylinder, the upper end
of which is closed, and having its lower edge or mouth dipping into
a body of suitable or luting fluid compound or substance in which

page_text: it works or moves up and down freely, practically without friction; for
this purpose mercury or any metallic compound fluid at a low steam
temperature, or any amalgam, or any suitable fatty or oleagenous
matters, or any mixture thereof, either alone or associated with certain
metals or metalloids (that when combined will form a semi-fluid lute
or sealing) may be used or employed.
When the pressure of the steam (or other fluid within the boiler or
other vessel) exceeds the resistance offered by the combined weight, and
the difference of pressure due to the reduced area of the piston in the
upper chamber, the valve in the lower chamber, or the safety or
discharge valve opens, and the steam is either freely discharged or dis-
charged into the "blow-off pipe" which should be connected with and
open from that portion of the lower chamber which is above the valve
scat when the valve is surrounded and inclosed as shown in most of the
views in illustration of this Invention.
By removing the cover plate from the top of the upper chamber the
weighted piston and the spindle may be withdrawn therefrom; and then by
removing the cover plate from the upper side or top of the lower chamber
the valve may be withdrawn from its seat.
The distance between the under side of the upper chamber and the
upper side of the lower chamber may be varied according to convenience,
and the space between the upper end of the piston and the inside of the top
cover of the upper chamber may be about one-fourth of the diameter of the
valve or more to permit of a sufficient lift to allow of a "free blow off."
A lever may (if it be desired) be jointed to or connected with the
valve spindle at some exposed portion thereof, by which the valve may
be lifted only, so that no pressure can be put on the valve beyond the
regulated load. A "Bourdon" or other pressure guage may be applied
to the cover plate or to any other convenient portion of the apparatus so
as to indicate the amount of pressure within either of the chambers or
cases. A small passage should be made, and a "drain cock" and .pipe
be applied to draw off any water (or condensed steam) that may collect
above the valve, or in the chamber between the top of the valve and the
blow off passage, (or in any other position where it may collect.)
Two or more safety valves with their pistons or the equivalent there-
for as described may be combined within the same chambered casting

page_text: or apparatus, and in most cases one opening to the boiler, and onc
"blow-off" pipe may be used in common for the passage of steam to
and from the several valves.
Instead of connecting the upper chamber (containing the piston or its
equivalent body or vessel) with the lower chamber containing the valve
and valve seat in manner as herein-before described, by means of a
steam passage or pipe (as herein-before mentioned) there may be a
second and separate, or more than one such opening made in the boiler;
and a steam pipe connecting the boiler to and with the upper chamber
only, by which the steam from the boiler is brought to bear directly upon
the upper end of the piston, plunger, disc, or vessel capable of working
freely up and down within the upper chamber. A steam cock or a
shut-off valve should be inserted in this connecting pipe, by means of
which when the steam is shut off from the top side of the piston (or its
equivalent) it is relieved of pressure, and the safety valve is left free
to rise and permit the free escape of steam from the boiler through the
valve scat in the lower chamber.
In consequence of the Board of Trade regulation by which steam
safety and blow-off valves of large area are required so as to prevent the
too rapid accumulation of volume and pressure of steam within the
boiler or steam generator, beyond the load per square inch at which the
free escape of steam from the boiler is intended to take place, the use of
dead weights for loading the safety valves of high-pressure boilers
becomes impracticable in sea-going ships, whilst the condition and
accuracy of spiral and other springs can be relied upon with
sufficient certainty. In these "differential safety valves," the very small
dead weight or load required upon the valve may be regulated in its
amount by the limit of the intended working pressure of steam in
pounds per square inch, which it may, for example, conveniently equal
in pounds dead weight, as it has only to operate against and to representa
the pressure upon the difference between the areas of the valve and the
piston.
The "differential safety valve" may, of course, be applied to other
vessels than steam boilers or steam generators, and for other purposes
than regulating the discharge of steam under pressure from boilers or a
generators, and the piston or its equivalent and counterweights, or the

page_text: dead load upon the valve may be changed, or be reduced to admit of the
boiler being worked at a lower pressure from time to time as the boiler
becomes worn and its ability to resist the original working pressure
becomes lessened.
We have illustrated by the aid of the twenty-nine Figures given on the
accompanying two Sheets of Drawings some of the more convenient modes
or methods of putting our Invention into practice, but the action and
performance of each and every of the safety valves or apparatus therein
illustrated and herein described, or of any mere modification thereof,
depends upon the steam pressure being brought to bear upon the under
side of a valve of a given area, and also at the same time upon the upper
side of a piston or disc of slightly lesser area than the valve, the two
being either connected or made to operate together through or by means
of a rod, pin, or spindle between them, or by any equivalent means; the
resistance to the opening of the lower valve being supplied by the weight
of the superimposed piston or its equivalent, or by additional weights
added (as herein described and illustrated, or in any other more con-
venient position or manner) so as to be equivalent to the sum of the
pressure of steam represented by its action on the under side of the
limited additional area of or in the safety or escape valve over and above
the pressure acting upon the upper side of the piston or disc, and
pressing down or keeping in its seat the safety or escape valve.
In some cases, as herein-before stated, we prefer, instead of fitting the
piston or plunger into and causing it to work up and down within or
through a stuffing box or in a packed gland (or to fit the same with
metallic or other similar packing) to use or employ an inverted cylin-
drical or bell-shaped vessel, the lower and open end or mouth of which
dips into a fluid, or semi-fluid, or other suitable luting or sealing, as
herein mentioned, and provided for the purpose and contained within
the lower part of the upper chamber, or in an annular space therein.
In the accompanying two Sheets of Drawings,--

page_text: Figure 2 (and Figure 5).
5 is a plan or top view of Figure 1.
6 is a horizontal sectional view of Figure 2 on the line B-B.
7 is a plan view of the cover plate of Figure 3.
8 is a horizontal sectional view of Figure 4 taken on the line
C-C.
5
1
9 is a sectional elevation of a double safety valve or apparatus,
and illustrates a modification in the arrangement of the steam
passage or connection between the under side of the
escape
valve and the top chamber, as also a variation in the arrange-
ment and mode of fitting and packing the piston or plunger.
10 is a front elevation of a double safety valve or apparatus, with
two escape, discharge, or blow-off passages, which may be
connected together by means of a breeches pipe or other 1
arrangement. It has also a hollow cylindrical piston opened
at the top, and into which weights may be placed to load it
to the required extent.
11 is a transverse vertical sectional view of Fig. 10.
12 is a vertical section of Fig. 10 on the line D-D of Fig. 10 2
(and of Fig. 13).
13 is a horizontal sectional view of Fig. 12 taken on the line
E-E.
14 is a plan view of the top plate or cover of Fig. 12.
15 is a horizontal sectional view of Fig. 12 on line F-F.
16 is a front elevational view of a single valve apparatus with a
double escape discharge or blow off connected with a breeches
pipe. In this apparatus the counterweight (or weights) or
load is fitted upon the exposed portion of the valve spindles
between the upper and the lower chamber. The steam pipe
or passage connecting the lower and the upper chamber is
similar to the arrangement shown in the several views; there
15 is a horizontal sectional view of Fig. 12 on line F-F.
16 is a front elevational view of a single valve apparatus with a
double escape discharge or blow off connected with a breeches
pipe. In this apparatus the counterweight (or weights) or
load is fitted upon the exposed portion of the valve spindles
between the upper and the lower chamber. The steam pipe a
or passage connecting the lower and the upper chamber is
similar to the arrangement shown in the several views; there

page_text: is
:
રી "Bourdon' pressure guage and a drain cock and pipe
fitted to the apparatus, which may be applied generally.
7 is a transverse (vertical) sectional view of part of Fig. 16, the
breeches pipe being left out.
8 is a front vertical sectional view of Fig. 16 taken on the
line GG, the breeches pipe not being in section.
9 is a plan view of Fig. 16 taken on the line H-H, without the
breeches pipe.
0 is a vertical side elevation or edge view of a double valve
apparatus to a similar scale to the previous Figures, and in
which the additional weights or the dead load is disposed or
placed as in Figures 16 to 19; but instead of having a solid
(or a hollow and loaded) piston working through a gland or
stuffing box it has attached to the valve spindle an inverted
cylinder or vessel open at the lower end, the lower edge or
mouth of which vessel dips into a fluid or semi-fluid to make
a luting or scaling within the lower part of the upper
chamber, which upper chamber, as well as the lower cover
of the chamber, is made hollow, and has an annular space
therein to form a reservoir for the luting or sealing fluid, as
shewn.
1 is a sectional clevation of a front view of Figure 20, and
shows the last described arrangement connected with the
upper chambers and their fittings more in detail.
1 is an enlarged view of the upper chambers, and the internal
arrangements therein shewn in Figure 21, the one chamber
being in section.
2 is a sectional plan of the upper chambers only of Figures
20 and 21, taken on the line I-I of Figure 21.
3 shows a modification of the piston arrangement fitted with
ordinary metallic packing rings.
4 is another modification of a piston and an arrangement of
packing.
5 is a horizontal sectional plan of Figure 24.

page_text: 26 is an external view of a shut-off valve, which may be inserted
in the steam passage or pipe connecting the upper with the
lower chamber to take off the top pressure, whether the top
chambers be supplied with steam direct from the boiler or
otherwise.
27 is a front elevation of a double valve apparatus, and shows a
modification in the arrangement by which the steam con-
necting passage or pipe between the upper and the lower
chamber of the apparatus is dispensed with, and by which
the steam pressure from the boiler is communicated dircct
to the piston in the upper chamber by an independent
steam pipe from the boiler, which pipe has a shut-off or
relief cock therein, as shown, and which may be worked (or
opened and closed) from any distant or more convenient place
by means of a handle, hand wheel, lever, or other convenient
contrivance. When the steam pressure from the boiler is shut
off from the piston in the top chamber, an escape or blow-off
cock is, at the same time and it may be by the same means,
opened to allow of the escape of the accumulated steam.
c 28 is a side clevation of Figure 27, and shows the shut-off cock
and gearing.
29 is a vertical sectional view of an upper chamber containing
the piston or disc, which in this case is shown with a flexible
corrugated diaphragm.
ch of the arrangements shown in the accompanying two Sheets the
nd blow-off or discharge valve is shown as inclosed within a
or case, from which the escape steam is discharged by a suitable
Yet the safety or discharge valve may instead thereof be mounted
eating, or on its seating in or upon a chamber or vessel, and the
hamber containing the piston, disc, or other arrangement (by
e counterpressure is brought to bear upon the valve) may be
1 upon or above, and be connected with the boiler, or with the
amber, as the case may be, in any convenient manner. The
ressure supplied to such upper chamber may be direct from the
a separate pipe, or by a pipe or passage from under the valve ;
Where the valve is open or unenclosed, and the steam discharged

page_text: from it is free to blow direct into the air, instead of through a steam
blow-off or discharge pipe.
The arrangements and disposition of the several parts of the apparatus
shewn in the several Figures in the accompanying two Sheets of Drawings
and the purpose for which they are respectively intended arc (or will be)
so readily understood by a careful or attentive reference thereto as to
render the use of distinguishing letters upon the several parts or portions
thereof, as also any further or more detailed description of the action and
performance of the several modifications of the apparatus shown on the
said two Sheets of Drawings unnecessary.
For the luting or scaling herein-before mentioned employed in the
manner, as shown in the views, Figures 20, 20ª, and cetra, as herein
described, mercury may be used, in which case we propose to cover the
surface with fatty or olcagenous matter.
Instead of mercury any suitable amalgam or a composition of metallic
and fatty or olcagenous matters may be employed, the boiling point of
which is sufficiently high whilst the fluid or semi-fluid state of which at
ordinary temperatures is sufficiently low to enable it to be employed for
this purpose with advantage; but we do not intend to make any claim
for the use of mercury for a sealing or luting, nor for the use and
employment of such materials, amalgams, or compositions for the
purpose of luting or sealing generally, as mercury has heretofore been
used or employed in a similar way for scaling the moving dome or bell
of gas pressure regulators and for other purposes.
When the difference between the greater area of the safety valve
(upon the under side of which the steam acts direct from the boiler) and
the lesser area of the piston in the upper chamber (and upon which the
steam pressure acts, and in conjunction with the dead weight holds down
the valve) is, say equal to one square inch, and when the pressure at which
the engine is to be worked is, say 80lbs. per square inch in the boiler,
then the weight of the piston, the valve spindle, and the valve may
together be say 80lbs., in which case the pressure of steam will have
to accumulate in the boiler to a pressure beyond cighty lbs. on each square
inch before the safety valve will open and allow the excess of steam to
escape therefrom. The actual amount or extent to which the internal
pressure of steam must accumulate may be equal to the amount of

page_text: friction to be overcome by the upward movement of the valve, the valve
spindle, and the piston, where it is a known and constant quantity, or
the slight difference of area equivalent thereto may be given by reducing
the area of the piston or disc. Where the weight of the piston, valve
spindle, and valve taken together is not equal to the load requisite to
be brought to bear on the difference of areas so as to load the valve to
the required pressure, then additional weights may be added either to
the valve spindle or within the piston (when it is made hollow or
chambered) for that purpose; and there may be an additional or
suspended weight (in addition to the calculated load which alone presses
upon the valve when it is closed, but after it has lifted beyond a
point to be regulated and fixed, this additional weight will then come
into action and assist in bringing down and closing the safety valve.
Where the safety or discharge valve is say five and a half inches
diameter or say equal to 23.75 square inches of area, the piston may
bc 5 inches full diameter, or say 22.70 to 22.75. Thus the difference
would be 1 square inch of area; and without taking account of the
frictional resistance, the weight of the piston, and of the several parts
superimposed on the safety valve should in such case be 70, 80, 90,
or 100lbs. according to or to agree with the pressure per square inch at
which the engine is to be worked, and before the valve is to blow off
or permit the free discharge of the steam from the boiler.
Another mode or method of overcoming the frictional resistance of
the piston, spindle, and moving parts during the downward movement
of the valve (or when the pressure has been reduced by "blowing off"
below the load at which it is regulated to work the machinery) is by
the employment of a lever arm or weighted lever (which is called into
action by the reduction of the pressure) or by mechanical means, tho
object being to overcome the frictional resistance to the downward
movement of the valve and its connections, and to give time for the free:
and full action of the steam pressure upon the upper side of the piston
or of the disc or diaphragm in the upper chamber.
Having herein described the nature of our Invention and illustrated in
the accompanying two Sheets of Drawings some of the modes or methods
in which we prefer to put it into practice, we claim as herein-before
stated the construction of safety and discharge valves having a piston

page_text: or other pressure, and in which apparatus the area of the safety or discharge
valve is greater than the area of the piston, as herein described
and set forth.
In witness whereof, we, the said George Allibon and Alexandre
Manbre, have hereunto set our hands and scals, this Thirtieth
day of June, One thousand eight hundred and seventy-three.
0 Witness,
WILLIAM SMITH, C. E.,
19, Salisbury St.,
Strand,
W. C.
GEORGE ALLIBON.
(L.S.)
ALEXANDRE MANBRÉ. (L.s.)