A COMBINED SAFETY VALVE REGULATOR, PRESSURE GUAGE, WATER INDICATOR ALARM; AND BLOW-OFF' FOR STEAM GENERATORS
Year: 1865

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields,
in the County of Middlesex, Gentleman, for the Invention of "A
COMBINED SAFETY VALVE REGULATOR, PRESSURE GUAGE, WATER INDICATOR
ALARM; AND BLOW-OFF' FOR STEAM GENERATORS."-A communication
from abroad by Peter Riordan, of Washington, D.C., in the United
States of America.
Sealed the 7th November 1865, and dated the 11th May 1865.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson
at the Office of the Commissioners of Patents, with his Petition, on
the 11th May 1865.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of
Middlesex, Gentleman, do hereby declare the nature of the said Invention
for "A COMBINED SAPETY VALVE REGULATOR, PRESSURE GUAGE, WATER INDICATOR,
ALARM, AND 'BLOW-OFF' FOR STEAM GENERATORS," a communication to me from
abroad by Peter Riordan, of Washington, D.C., in the United States of
America, to be as follows:-
This Invention relates to a combined apparatus intended to be applied to
steam generators, and serving as a safety valve regulator, a pressure guage, a
water-level indicator, an alarm, and a "blow-off" apparatus. This combined
Price 8d.1

page_text: apparatus consists of a cylinder, the upper part of which is of rather larger
diameter than the lower portion, each portion having a piston working steam-
tight therein. These pistons are both secured to a hollow piston rod working
through a stuffing box in the top of the large end of the main cylinder; the
space included between these two pistons is in free communication with the
atmosphere. Apertures are made in the side of the cylinder, so as to admit
steam from the boiler above the larger piston and below the smaller one.
Apertures are made in the sides of the hollow piston rod, admitting steam
therein from the larger cylinder, and other apertures are made in such piston
rod in the part outside the stuffing box to serve as a "blow-off." Inside this
hollow piston rod, and between the upper and lower lateral apertures above
referred to, works a piston valve connected to a spindle, which
passes upwards
inside the hollow piston rod. A screw thread is cut on the piston rod, and
on it works an adjustable nut or collar, to which is connected at its lower end
a spiral spring, the upper end of which spring is connected with the spindle
of the piston valve above referred to. This spindle is provided with a rack,
which gears into a toothed wheel in connection with the indicator of a pressure
guage. The dial of the pressure guage is slipped on to the hollow piston rod,
and is connected by a short cylinder with the adjustable nut or collar, so that
when that collar is moved up or down the dial will also move up or down on
the hollow piston rod, the front face of which is graduated. The main
cylinder or body of the apparatus is connected at its lower end with the
boiler in such a way as to afford free water communication between the
boiler and the lower portion of the cylinder, the water in the cylinder standing
at the same level as th it in the boiler. In this portion of the cylinder there
is provided a float, which is connected to a vertical spindle and rack gearing
into a toothed wheel, which gives motion to an index or pointer. This spindle
works inside the hollow piston rod, and is provided with two piston valves
fitting steam-tight inside such rod. As the float rises and falls the piston
valves move up or down, and the rack imparts motion to the index or pointer,
which indicates on a suitably marked semicircle the different heights of the
water level. A flexible tube communicates with the interior of the hollow
piston rod, and is attached to an alarm whistle situated outside the main
cylinder of the apparatus, and gives an alarm when steam escapes there-
through. When steam is generated in the boiler it enters the cylinder and
exerts a downward pressure on the larger piston and an upward pressure on
the smaller piston, but the upper one has an effective area greater than the
lower one by as much as the area of the safety valve divided by the number of
times the long arm of the safety valve lever is greater than the short arm, after

page_text: The
allowing for the weight of such parts of the apparatus as may have a gravitating
effect on the lever. For example, if the total lifting power of the safety valve
at the end of the lever attached to the hollow piston rod above referred to
be 33 pounds when the pressure in the boiler is, say, fifty pounds on the
square inch, and that the weight of the parts acting by gravity on the lever
be S pounds, and the effective area of the upper piston be two square inches,
then the effective area of the lower piston must be 1 square inches, leaving
a difference in favor of the larger piston of 25 pounds total pressure, which is
what is required to counteract the lifting power of the safety valve on the end
of the lever; it will then be in equilibrium, and no steam will blow off.
adjustable collar above referred to is screwed down to a point on the graduated
hollow piston rod, and by bringing down with it the spiral spring and the
spindle and piston valve herein-before referred to connected therewith. Steam
will enter the hollow piston rol by lateral openings made therein from the
larger portion of the cylinder above the larger piston, and will force up the
piston valve, at the same time compressing the spiral spring until on arriving
at a pressure of 50 pounds on the square inch the piston valve will be opposite
the lateral apertures for the "blow-off," but on rising to 51 pounds the piston
valve will rise sufficiently to allow the steam to escape through the blow-off
apertures, and thus prevent the total pressure on the larger piston from
becoming more than 100 pounds, whilst at the same time the total upward
pressure on the smaller piston is from 75 lbs. to 76 lbs, which, of course,
reduces the holding-down power of the larger piston on the safety valve
lever, and will act in a similar manner to the ordinary spring balance,
supposing that to be suddenly unscrewed, from 50 to 48 of its controlling
power; and should the pressure increase to 52 lbs. per square inch the
total upward pressure on the smaller piston will be 78 lbs., whilst the
total downward pressure on the larger piston cannot exceed 100 lbs. This
action is reversed as the steam falls to its proper pressure. It will thus
be obvious that so long as no steam is allowed to blow off through the lateral
blow-off apertures in the hollow piston rod the safety valve cannot possibly
blow off, but when steam is allowed to blow off through such lateral apertures
then the safety valve will always blow off at a rate increasing in proportion to
the increase of pressure in the boiler. When the water in the boiler gets
dangerously low the descent of the float in the lower portion of the cylinder
will draw down the piston valves connected therewith until the upper one
descends below the orifice of the flexible tube leading to the alarm whistle,
and consequently steam will rush through the whistle, and sound the necessary
aların. Should this alarm be disregarded the further descent of the piston

page_text: valve last referred to will open a large steam exit in the side of the hollow
piston rod, through which the steam will rush into the atmosphere from
above, the larger piston thus reducing the pressure thereon, and consequently
allowing the safety valve to blow off in the same manner as when the steam
blows off through the lateral blow-off apertures in the hollow piston rod above
referred to. This will have the effect of almost instantaneously reducing the
pressure in the boiler, and the blowing off will continue either until the water
level is restored to its proper height, or until there is no longer any pressure
in the boiler.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Henry Johnson in the Great Seal Patent Office
on the 11th November 1865.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eleventh day of May, in the year of our Lord
One thousand eight hundred and sixty-five, in the twenty-eighth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said John Henry Johnson, Her special licence that I, the said John
Henry Johnson, my executors, administrators, and assigns, or such others as
I, the said John Henry Johnson, my executors, administrators, or 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 "A
COMBINED SAFETY VALVE REGULATOR, PRESSURE GUAGE, WATER INDICATOR ALARM,
AND BLOW-OFF FOR STEAM GENERATORS," a communication to me from abroad
by Peter Riordan, of Washington, D.C., in the United States of America,
upon the condition (amongst others) that I, the said John Henry Johnson,my
executors or administrators, by an instrument in writing under my hand and
sealshould particularly describe and ascertain thenatureof 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 calender months next and
immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said John Henry Johnson, do hereby

page_text: declare the nature of the said Invention, and in what manner thesame is to
be performed, to be particularly described and ascertained in and by the
following statement, reference being had to the accompanying Drawings, and
to the letters and figures marked thereon, that is to say :-
The said Invention relates to a combined apparatus intended to be applied
to steam generators, aud serving as a safety valve regulator or pressure
guage, a water-level indicator, an alarm, & a "blow-off" apparatus.
The aunexed Drawing represents a sectional elevation of this combined
apparatus in working order; it consists of a cylinder A, B, the upper part A
of which is of rather larger diameter than the lower portion B, each portion
having a piston C, D, working steam-tight therein; these pistons are both
secured to a hollow piston rod E, working through a stuffing box F in the
top of the larger end of the main cylinder; the space included between these
two pistons is in free communication with the atmosphere through the lateral
aperture G. Apertures a and b are made in the side of the cylinder A, B, so
as to admit steam from the boiler above the larger piston C and below the
smaller one D. c, c, are apertures made in the sides of the hollow piston rod
for admitting steam therein from thelarger cylinder A, and other aperturesd,d,
are made in such piston rod in the part outside the stuffing box to serve as a
"blow off." Inside this hollow piston rod, and between the upper and lower
lateral apertures c and d above referred to, works a piston valve H, connected
to a spindle I, which passes upwards inside the hollow piston rod E, which
rod is connected at its upper end to the safety valve lever, not shown in the
Drawing. A screw thread is cut on the fixed vertical standard K, and on it
works an adjustable nut or collar L, to which is connected, so as to all the
nut to revolve freely, the boss e of an arm f, which passes through a vertical
slot in the hollow piston rod, and is attached to the lower end of a spiral
spring M, the upper end of this spring being connected with the spindle of
the piston valve H above referred to. The spindle has formed upon it a
rack 9, which gears into a toothed pinion for actuating the indicator or
hand O of adial pressure gauge. Motion is transmitted to the indicator from
the axis of pinion h by the second pinion i, in gear with a toothed wheel kc, on
the axis of which is fitted the indicator or hand O of the guage. The dial P
of the pressure guage, and the parts connected therewith, is connected to the
boss e above referred to, so that when that boss is moved up or down by
turning the nut or collar Lthe dial will also move up or down the standard K,
the front of which must be graduated for the regulation of the pressure, and
the top of the same should be divided or forked, so as not to interfere with the
axis of the indicator or hand O. By making the dial P adjustable vertically

page_text: the moving up or down of the spindle I by the nut Lean have no action on
the hand O, which can be operated only by the pressure of the steam. The
main cylinder or body of the apparatus is connected at its lower end by a
pipe Q with the boiler in such a way as to afford free water communication
between the boiler and the lower portion of the cylinder B, the water in the
cylinder standing at the same level as that in the boiler. In this portion of
the cylinder there is provided a float R, which is connected to a vertical
spindle and rack m, gearing into a toothed pinion n, which gives motion to
aa index or pointer $ through the second pinion and toothed wheel o and p
respectively. This spindle works inside the hollow piston rod E, and is
provided with two pistou valves T and U fitting steam-tight inside such
hollow rod. As the float R rises and falls the piston valves T and U move
up or down, and the rack m imparts motion to the index or pointer S, which
indicates on a suitably marked fixed semicircular dial V the different heights
of the water level. A flexible tube q communicates with the interior of the
hollow piston rod below the piston valve T and is attached to an alarm
whistle W, situate outside the main cylinder of the apparatus, and gives an
alarm when steam escapes therethrough. The action of this apparatus is as
follows: When steam is generated in the boiler it enters the cylinder A. B,
through the orifices and pipes a and b, and exerts a downward pressure on the
larger piston Cand an upward pressure on the smaller piston D, but the upper
one has an effective area greater than the lower one by as much as the area
of the safety valve divided by the number of times the long arm of the safety
valve lever is greater than the short arm, after allowing for the weight of such
parts of the apparatus as may have a gravitating effect on the lever. For
example, if the total lifting power of the safety valve at the end of the lever
attached to the hollow piston rod E above referred to be 33 lbs. when the
pressure in the boiler is, say, 50 lbs. on the square inch, and that the weight
of the parts acting by gravity on the lever be 8 lbs., and the effective area of
the upper piston be 2 square inches, then the effective area of the lower
piston must be 1 square inches, leaving a difference in favor of the larger
piston of 25 lbs. total pressure, which is what is required to counteract the
lifting power of the safety valve on the end of the lever; it will then be in
equilibrium, and no steam will blow off. The adjustable collar L above
referred to is screwed down to a given point on the graduated standard K
bringing down with it the spiral spring M. and the spindle and piston valve I
and H hereinbefore referred to connected therewith. Steam will enter the
hollow piston rod E by the lateral openings made therein at c, c, from the
larger portion A of the cylinder above the larger piston C, and will force up

page_text: the piston valve H, at the same time compressing the spiral spring M until
on arriving at a pressure of 50 lbs. on the square inch the piston valve H will
be opposite the lateral apertures for the "blow off," but on rising to 5.1 lbs.
the piston valve H will rise sufficiently to allow the steam to escape through
the blow-off apertures d, d, and thus prevent the total pressure on the larger
piston C from exceeding 100 lbs., whilst at the same time the total upward
pressure on the smaller piston D is from 75 lbs. to 76 lbs., which, of course,
reduces the holding-down power of the larger piston on the safety valve lever,
and will act in a similar manner to the ordinary spring balance, supposing
that to be suddenly unscrewed from 50 to 48 of its controlling power; and
should the pressure increase to 52 lbs. per square inch the total upward
pressure on the smaller piston D will be 78 lbs., whilst the total downward
pressure on the larger piston C cannot exceed 100 lbs. This action is
reversed as the steam falls to its proper pressure. It will thus be obvious
that so long as no steam is allowed to blow off through the lateral "blow-off"
apertures d, d, in the hollow piston rod the safety valve cannot possibly blow
off, but when steam is allowed to blow off through such lateral apertures then
the safety valve will always blow off, at a rate increasing in proportion to the
increase of pressure in the boiler. When the water in the boiler gets
dangerously low the descent of the float R in the lower portion of the
cylinder B will draw down the piston valves T, U, connected therewith until
the upper one T descends below the orifice of the flexible tube q leading to
the alarm whistle W, and consequently steam will rush through the whistle
and sound the necessary alarm. Should this alarm be disregarded the further
descent of the piston valve T' will open a series of slots or steam exits r, r, in
the side of the hollow piston rod, through which the steam escaping from
above the larger piston Cthrough the aperture c will rush into the atmosphere,
thus reducing the pressure upon such piston, and consequently allowing the
safety valve to blow off in the same manner as when the steam blows off
through the lateral blow-off apertures d, d, in the hollow piston rod. This
will have the effect of almost instantaneously reducing the pressure in the
boiler, and the blowing off will continue either until the water level is
restored to its proper height, or until there is no longer any pressure in the
boiler.
1
Having now described and particularly ascertained the nature of the said
Invention, and the manner in which the same is or may be used or carried
into effect, I would observe in conclusion, that what I consider to be novel
and original, and therefore claim as the Invention secured to me by the
herein-before in part recited Letters Patent is, the peculiar construction,

page_text: arrangement, and combination of apparatus to be used as a combined safety
valve regulator, pressure gnage, water-level indicator, alarm, and "blow off"
for steam generators, substantially as herein-before described.
In witness whereof, I, the said John Henry Johnson, have hereunto
set my hand and seal, the Tenth day of November, One thousand
eight hundred and sixty-five.
J. HENRY JOHNSON. (L.s.)