IMPROVEMENTS IN SAFETY VALVES
Year: 1872

page_text: LETTERS PATENT to Thomas Giles, of No. 55, Greenhill Street,
Greenheys, Manchester, in the County of Lancaster, Machine Fitter,
for the Invention of "IMPROVEMENTS IN SAFETY VALVES."
Sealed the 23rd August 1872, and dated the 23rd March 1872.
PROVISIONAL SPECIFICATION left by the said Thomas Giles at the
Office of the Commissioners of Patents, with his Petition, on the
23rd March 1872.
I, THOMAS GILES, of No. 55, Greenhill Street, Greenheys, Manchester,
in the County of Lancaster, Machine Fitter, 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. For
this purpose to a valve seating attached to the boiler a valve is fitted,
and upon the valve is a tubular case containing a spiral spring sur-
rounding a spindle fixed in the top of the valve. The spring rests upon
a disc or collar upon the spindle, and is pressed down at the top by a

page_text: cover fitting the tubular case on the valve. The spring is thus enclosed
so as to exclude the steam from it.
The valve with the spring and case containing it are enclosed in an
outer coating screwed on the outside of the valve seating, and the cover
already mentioned by which the spring is pressed down screws into the
upper end of the casing. The valve has a projecting flange upon it
which nearly fits the lower part of the outer casing, but the casing is of
larger diameter immediately above; thus as soon as the valve commences
to lift the pressure comes on the larger area of the valve flange, and
raises it higher, until it is above the contracted part of the outer casing.
The amount of lift can be adjusted by screwing the outer case up or
down upon the valve casing.
The steam passing the valve ascends between the inner case and the
outer casing, passes through holes in the cover of the case, and then
through a perforated cap which closes the outer casing at the top.
To prevent tampering with the valve and altering its adjustment
without the knowledge of the engineer, the screws which attach the
perforated cap are covered, and a padlock holds the cover in place.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Thomas Giles in the Great Seal Patent Office on 2
the 23rd September 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
GILES, of No. 55, Greenhill Street, Greenheys, Manchester, in the
County of Lancaster, Machine Fitter, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her 2
Letters Patent, bearing date the Twenty-third day of March, in the year
of our Lord One thousand eight hundred and seventy-two, in the
thirty-fifth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Thomas Giles, Her special license
that I, the said Thomas Giles, my executors, administrators, and 3
assigns, or such others as I, the said Thomas Giles, my executors,
administrators, and assigns, should at any time agree with, and no
others, from time to time and at all times thercafter during the term

page_text: 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 Giles, 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 date of the said Letters
Patent.
NOW KNOW YE, that I, the said Thomas Giles, 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. For
this purpose a valve is fitted to the valve seating, and upon the valve is
a tubular case containing a spiral spring surrounding a spindle fitted in
the top of the valve. The spring rests upon a disc or collar upon the
spindle, and is held down at the top by a cover fitting the tubular case
on the valve. The spring is thus enclosed so as to exclude the steam
from it.
The valve with the spring and case containing it are enclosed in an
outer casing screwed on the outside of the valve seating, or otherwise
fixed, and the cover already mentioned by which the spring is held down
screws into the upper end of the casing. The valve has a projecting
flange upon it which nearly fits a cylindrical recess formed at the lower
part of the outer casing, but the casing is of larger diameter immediately
above; thus as soon as the valve commences to lift the pressure comes
on the larger area of the valve flange, and raises it higher until it is
above the contracted part of the outer casing. The amount of lift can
be adjusted by screwing the outer case up or down upon the valve
casing, so as to vary the depth of the recess, or the depth of the recess
may be otherwise varied.
The steam passing the valve ascends between the inner and outer

page_text: Figure 1 is a vertical section of a safety valve constructed according
to my Invention, and suitable for locomotive and other boilers. a is a
valve seating, which with other parts a¹ and as formed with it is bolted
to the boiler; b is the valve, it has the tubular casing 6' formed with
it ; 62 are guide wings upon the valve; c is a spindle which is received
into a socket formed for it in the valve; c' is a disc upon the spindle,
which receives the pressure of the coiled spring d; e is the cover of the
tubular casing 6', it holds the spring down, and also prevents the steam
coming in contact with it. A spring ring is fitted at e¹ into a groove in
the cover to make a close and easy fit to the interior of the casing 6¹;
e² are perforations arranged in a ring around the cover for the escape of
the steam. The cover e is screwed into the top of the outer casing a¹,
which, as represented in this Figure, is cast with the valve seat. The
pressure of the spring on the valve is adjusted by causing the cover e to
enter more or less far into the outer casing a¹. The spindle c passes
through a hole in the cover e; f is a locking ring, it is placed over the
cover e, and a stud upon it enters one of the holes e³; 9 is a perforated
cover fixed upon the top of the outer casing a¹ by the screws g¹; these
screws also secure the locking ring f, and they may be padlocked. 6ª is
a projecting flange on the valve, it enters into the recess a³ formed
around the valve seat, so that when the valve lifts the steam accumulates
in this recess, and its pressure upon the flange b³ aids in lifting the valve.
The pressure on this flange compensates for the increased resistance of
the spring as it is compressed, and will be more or less according to the
width of the clearance left between the flange 6³ and the sides of the
recess a². A wide opening of the valve is thus secured before the
pressure in the boiler has risen far above the point at which the valve
first rises from its seat.
The amount of opening will depend on the depth of the recess or
cavity a³, and this may be adjustable, as is shewn by Figures 2 and 3,
so as to raise its lip more or less above the lower edge on the flange of
the valve.
Figure 4 is a safety valve suitable for marine use; here the escape for

page_text: THOMAS GILES. (L.S.)