IMPROVEMENTS IN SAFETY VALVES FOR STEAM BOILERS
Year: 1854

page_text: PROVISIONAL SPECIFICATION left by Sir George. Richard Farmer at
the Office of the Commissioners of Patents, with his Petition, on the
27th April 1854.
I, Sir GEORGE RICHARD FARMER, Baronet, of Bideford, in the County of
Devon, do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN SAFETY VALVES FOR STEAM BOILERS" to be as follows:-
The improved safety apparatus consists, 1st, of three. distinct and separate
valves of different sizes; one of which acts as a relief valve; they are placed
in a single plate of metal screwed or rivetted on to the boiler; 2nd, of
their rods or stalks; 3rd, of two upright side posts; 4th, of three cross
rails; and 5th, of an inverted cylindrical dish and piston, placed at the safety
level of the water in the boiler. The stalks work through the three cross rails
inserted into suitable uprights or posts outside the valve. The lower cross rail
is tenoned at each end, to allow it to work vertically in a mortice made for this
purpose in the side posts. The tenons project two inches beyond the posts for
the purpose hereafter stated. The stalks of the piston and valves are made
round, to work freely in the holes in the cross rails, and project a sufficient
height above the upper bar to allow weights to be placed thereon. The stalks
of the two outside valves are thicker from their junction with the valves, as far
as the lower side of the bottom cross rail, than they are from thence to the top,
to form a shoulder to force up the lowest cross rail when the valves are
opened by steam; but the shoulder on the stalk of the relief valve should not

page_text: be in contact with the cross rail. Sufficient space should be left for the relief
valve to act without forcing up the rail. The size of the valves will depend
upon the dimension of the boilers. Supposing the two outside valves to be
each three inches in diameter, the double centre valve will be seven inches in
diameter. This double valve is formed of two parts, one within the other.
The middle or inner division of this valve will be four inches in diameter, with
a round hole in the middle of about one inch diameter for the piston rod to
work through; the outer division or rim of this double valve will be three
inches wide all round, so 'that the opening for the escape of steam when both
parts of this valve are forced open will be about six inches in diameter, equal
to to the diameter of both side valves. The inner division of this valve is
fastened to the lower cross rail by pins or bars, one on each side of the piston
rod, so that the centre division can be raised up by the action of the outside
valves on the lower cross rail without disturbing the outer division, thereby
furnishing at all times the additional security of two, if not three, apertures
for the escape of steam, and at the same time admitting cold water into the
boiler, as described below. Half way between the double valve and lower
cross rail a small bar will pass through the piston rod, from which pins
descend to the outside division of the double valve, to secure it to the piston
rod, so that the whole of the valves will be opened when the piston in the
inverted dishi fixed in the boiler is acted upon by the steam from decrease of
water to below the safety level. The inverted dish is suspended from the
inside of the top of the boiler in stationary and locomotive engines by bars or
rods, or by bars from side to side of the boiler. A metal tube is fixed from
the outside of the top of the dish, passing through the double valve and two
lower cross rails, to prevent the ingress of steam into the dish. In this tube
the piston rod works. For marine engine boilers, the dish must be suspended
the same way in which inverted compasses .are hung in ships' cabins, i. e. in
..double hoops,. that it may swing in each direction of the pitch or roll of the
vessel, and keep the mouth of the dish level in the water. In order that the
dish may always keep it proper level in marine boilers, and the piston work.in
a proper position, a joint must be made in the piston rod a little above the
dish; for this purpose a spherical joint is formed that will work in every
direction, and keep the piston and dish in their proper position under all cir-
'cumstances. To prevent the ingress of steam into the inverted dish in marine
boilers, a case of india-rubber is to be attached to the outside of the top of the
dish and on to the piston rod, nearly up to the joint; the case is creased down
to allow it to expand when the rod is forced upwards. For the admission of
cold water into the boiler, a connecting rod suspended from the tenon at each

page_text: end of the lower cross rail is attached to a cock in connection with the inside
of the boiler, so that when the rail is forced up the cock opens, and the cold
water reduces the temperature of the boiler instantaneously by this self-acting
motion. Instead of levers and weights to keep down the valves, metal cases
are used filled with india-rubber. These cases are placed between the cross
rails, and have loose tops and bottoms to fit the inside. The bottom plate
rests on pins passed through the stalks or rods, each stalk passing through
the middle of the top and bottom plate and india-rubber. When the valves
are forced open, the case is forced upward above the cross rail, pieces being
cut out of the case on each side for this purpose, and the india-rubber is
thereby compressed against the upper rail. To preserve the india-rubber from
the heat of the stalk, a spiral spring or rings of ivory is placed on the stalk.
To regulate the downward pressure, a small weight with a hole in the centre
is placed on the stalk, and rests on a shoulder left for that purpose.