IMPROVEMENTS IN SAFETY VALVESMORAND
Year: 1875

page_text: In the Matter of a Patent granted to THOMAS ADAMS, of the Works of the
44
"
Ant" and the "Bee," West Gorton, Manchester, in the County of
Lancaster, for the Invention of IMPROVEMENTS IN SAFETY VALVES,"
bearing date the 29th day of October 1875, No. 3761.
DISCLAIMER AND MEMORANDUM OF ALTERATION proposed to be entered
by the said Thomas Adams, as such Patentee as aforesaid, pursuant to the
Statutes in that case made and provided.
WHEREAS since filing the Specification to the said Letters Patent I have been
advised that the claim which I have there made is too wide, and comprises matters
that were published in this country before the date of the said Patent:
And whereas I have found in the said Specification certain clerical errors, or errors
per incuriam.
I for these reasons desire to disclaim and alter the said Specification, and I do
bereby disclaim and alter the same, by inserting at page 3 of the Specification, as
it is printed by Her Majesty's Printers, and at line 28, after the word "correspond,"
the words "no claim is made to this form and proportions of spring as being any
part of my Invention intended to be claimed ;" and at page 3, line 33, by inserting
after the words "of the" the words, "square of the ;" and after the word "dia-
meter" the words, "of the valve seat;" and by omitting after the letter "A" tho
letter "B;" and by inserting after the words "to the " the words, "square of the;"
and after the word "diameter" the words, "of the valve seat;" and at page 4,
line 24, by omitting the words "and their springs."
And in order that the effect of this Disclaimer and Memorandum of Alteration
may be better understood, I annex a copy of the Specification as it will appear when
such Disclaimer and Memorandum of Alteration is made as aforesaid.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
ADAMS, of the Works of the "Ant" and the "Boe," West Gorton, Manchester, in
the County of Lancaster, send greeting:

page_text: WHEREAS Her Most Excellent Majesty Queen Victoria by Her Letters Patent
bearing date the Twenty-ninth day of October, in the year of our Lord One
thousand eight hundred and seventy-five, in the thirty-ninth year of Her reign,
did for Herself, Her heirs and successors, give and grant unto me, the said Thomas
Adams, Her special license that I, the said Thomas Adams, my executors,
administrators, and assigns, or such others as I, the said Thomas Adams, my
executors, administrators, and assigns, should at any time agree with, and no others,
from time to time, and at all times thereafter during the terin 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 "IMPROVEMENTS IN SAFETY VALVES," upon the condition (amongst
others), that I, the said Thomas Adams, my executors or administrators, by
an instrument in writing under my, 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 dato
of the said Letters Patent.
NOW KNOW YE, that I, the said Thomas Adams, do hereby declare the
nature of the said Invention, and in what manner the same is to be performed, to
be particularly described and ascertained in and by the following statement thereof,
that is to say :-
This Invention has for its object improvements in safety valves, and applies to
that class of safety valves in which when the valve begins to lift the steam acts
beneath a flange upon it, and causes it at once to open wide.
I am able to construct these valves so that they open suddenly to a constant
fixed height, and there stand until the pressure is reduced slightly below the point
to which the valve is loaded, when they close as suddenly as they have opened.
This result is attained by giving suitable forms and proportions to every part.
In the annexed Drawings,-
Figure 1 represents a section of the valves and its seat, the valve being shown
raised from its seat the distance which in practice it will be found to lift.
Figure 2 shows the form and proportions of the spring (uncompressed) which I
employ to load the valves.
I make my springs of the best cast steel, and the spring shown is suitable for a
pressure of about 85 lbs. per square inch.
If the valve is to be loaded to a lower or higher pressure I decrease or increase
the section of metal in the spring proportionally to the decreased or increased
pressure, varying also the other dimensions of the spring to correspond.
No claim is made to this form and proportions of spring as being any part of my
Invention intended to be claimed.
I proportion the parts of the valve as follows:-Whatever the pressure at which
it is desired that the valve should work, the distance the valve lifts should be of
the diameter at A, B, where the valve seats and the angles should bo, as indicated
in the Drawings.
The proportion of the squaro of the diameter of the valve seat at A to the square
of the diameter of the valve seat at the stricture orifice O, D, will vary with the
strength of the spring; when the load on the spring is one-sixth of the breaking
strain, as I prefer, the proportions of the diameters should be as 1 to 1·85; if one-
fourth, 1 to 17; if one-third, 1 to 1.5.
The proportion of the area of the escape orifice at A, B, to the stricture orifico
at C, D, will vary with the pressure. I calculate the area at C, D, by multiplying
the area at A, B, by the fraction R x V
R
R' × V¹
= Relative volume of steam to water at boiler pressure.
V = Velocity at which boiler steam would rush into a vacuum (number give by

page_text: R' = Relative volume of steam at 12 lbs. over atmosphere.
V₁ = Velocity of 12 lb. steam into a vacuum.
I proportion the spring in the following way:-Draw any straight line A, G, at
the centre line of the spring, draw A, B, A, C, indefinitely as the two sides of an
isosceles triangle, such that the angle B, A, C, contains 15°; select any point o in
A, G, as the length of spring required; divide O, C, into three equal parts, of
which O, H, is equal to two parts; on O, as a centre, with O, H, as radius, describe
the semicircle E, G, H; on G as a centre with the same radius, set off the arc G, E;
draw E, F, E, D, sine and cosine of the angle E, O, G; join E, O; E, D, will be
the sido of square of steel from which to make the spring, and E, F, will be the
pitch of spring, and E, O, will be the deflection of spring with its proper load
of 4th the breaking strain on it, and E, F, will divide O, A, into thirteen and a half
equal parts, and the angle B, A, C, is the angle of stability of the spring.
What I claim is the construction of safety valves in the manner and according
to the proportions herein-before set forth.
In witness whereof, I, the said Thomas Adams, have hereunto set my hand
and scal, this Twenty-third day of February, One thousand eight hundred
and seventy sight
Signed, sealed, and delivered, by the above-
named Thomas Adams, in the presence of
the words "with O, H, as radius describes
the semicirclo E, G, H, on G' as a centre,"
having been first interlined between the
sixth and seventh lines of the last sheet
hereof
I hereby grant my fiat, giving leave to the above-named Thomas Adams, to
file in the Great Seal Patent Office, with the Specification to which the same
relates, the above written Disclaimer and Memorandum of Alteration.
Dated this 27th day of December 1878.
JOHN HOLKEB,
Attorney-General.

page_text: LETTERS PATENT to Thomas Adams, of the Works of the "Ant"
and the "Bec," West Gorton, Manchester, in the County of
Lancaster, for the invention of IMPROVEMENTS IN SAFETY VALVES.
PROVISIONAL SPECIFICATION left by the said Thomas Adams at
the Office of the Commissioners of Patents, with his Petition, on
the 29th October 1875.
I, THOMAS ADAMS, of the Works of the "Ant" and the "Bee,"
West Gorton, Manchester, in the County of Lancaster, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN SAFETY
VALVES," to be as follows:-
This Invention has for its object improvements in safety valves, and
applies to that class of safety valves in which, when the valve begins to
lift, the steam acts beneath a flange upon it, and causes it at once to
open wide. I am able to construct these valves so that they open
suddenly to a constant fixed height, and there stands until the pressure
is reduced slightly below the point to which the valve is loaded, when

page_text: they close as suddenly as they have opened. This result is attained by
giving suitable forms and proportions to every part.
In the annexed Drawings Figure 1 represents a section of the valve
and its seat, the valve being shown raised from its seat, the distance
which in practice it will be found to lift.
Figure 2 shows the form and proportions of the spring (uncompressed)
which I employ to load the valve.
I make my springs of the best cast steel, and the spring shown is
suitable for a pressure of about 85 lbs. per square inch. If the valve is
to be loaded to a lower or a higher pressure I decrease or increase the
section of metal in the spring proportionally to the decreased or
increased pressure, varying also the other dimensions of the spring to
correspond.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Thomas Adams in the Great Seal Patent Office 1
on the 29th April 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
ADAMS, of the Works of the "Ant" and the "Bec," West Gorton,
Manchester, in the County of Lancaster, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her a
Letters Patent, bearing date the Twenty-ninth day of October, in the
year of our Lord One thousand eight hundred and seventy-five, in the
thirty-ninth year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said Thomas Adams, Her special
license that I, the said Thomas Adams, my executors, administrators,
and assigns, or such others as I, the said Thomas Adams, my
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 "Im-
PROVEMENTS IN SAFETY VALVES," upon the condition (amongst others) that I,
the said Thomas Adams, my executors or administrators, by an instrument

page_text: in writing under my, 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 immediatly after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Thomas Adams, do hereby
declare the nature of the said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained
in and by the following statement thereof, that is to say:
-
This Invention has for its object improvements in safety valves, and
applies to that class of safety valves in which, when the valve begins to
lift, the steam acts beneath a flange upon it, and causes it at once to
open wide. I am able to construct these valves so that they open
suddenly to a constant fixed height, and there stand until the pressure
is reduced slightly below the point to which the valve is loaded, when
they close as suddenly as they have opened. This result is attained by
giving suitable forms and proportions to every part.
In the annexed Drawings Figure 1 represents a section of the valve
and its seat, the valve being shown raised from its seat the distance
which in practice it will be found to lift.
Figure 2 shows the form and proportions of the spring (uncompressed)
which I employ to load the valve.
I make my springs of the best cast steel, and the spring shown is
suitable for a pressure of about 85 lbs. per square inch. If the valve is
to be loaded to a lower or higher pressure I decrease or increase tho
section of metal in the spring proportionally to the decreased or
increased pressure, varying also the other dimensions of the spring to
correspond.
I proportion the parts of the valve as follows:-Whatever the pressure
at which it is desired that the valve should work, the distance the valve
lifts should be of the diameter at A, B, where the valve seats and
the angles should be as indicated in the Drawings.
The proportion of the diameter at A, B, to the diameter at the
stricture orifice C, D, will vary with the strength of the spring when
the load on the spring is one-sixth of the breaking strain, as I prefer the

page_text: The proportion of the area of the escape orifice at A, B, to the
stricture orifice at C, D, will vary with the pressure. I calculate the
area at C, D, by multiplying the area at A, B, by the fraction RX V.
Rx
Rx V
area at C, D, by multiplying the area at A, B, by the fraction RX V.
R=Relative volume of steam to water at boiler pressure.
V=Velocity at which boiler steam would rush into a vacuum (number
give by well-known tables).
R' Relative volume of steam at 12 lbs. over atmosphere.
V₁=Velocity of 12 lb. steam into a vacuum.
]
I proportion the spring in the following way:-Draw any straight
line A, G, as the centre line of the spring; draw A, B, A, C, indefinitely
as the two sides of an isosceles triangle, such that the angle B, A, C,
contains 15°; select any point O in A, G, as the length of spring required;
divide O, C, into three equal parts, of which O, H, is equal to two 1
parts; on O, as a centre with O, H, as radius, describe the semi-
circle E, G, H; on G, as a centre with the same radius, set off the
arc G, E; draw E, F, E, D, sinc and cosine of the angle E, O,
join E, O; E, D, will be the side of square of steel from which to make
the spring, and E, F, will be the pitch of spring, and E, O, will be the 2
deflection of spring with its proper load of th the breaking strain on
it; and E, F, will divide O, A, into thirteen and a half equal parts; and
the angle B, A, C, is the angle of stability of the spring.
G;
What I claim is, the construction of safety valves and their springs
in the manner and according to the proportions herein-before set forth. 2
In witness whereof, I, the said Thomas Adams, have hereunto
set my hand and seal, this Twenty-ninth day of April, in the
year of our Lord One thousand eight hundred and seventy-
six.