IMPROVEMENTS IN SAFETY VALVES OR SAFETY APPARATUS FOR STEAM BOILERS
Year: 1880

page_text: PROVISIONAL SPECIFICATION left by William Edward Gedge at the Office
of the Commissioners of Patents on the 13th January 1880. A communi-
cation from abroad by Emile Saint Pierre, of Rueil (Seine et Oise), France
Engineer.
WILLIAM EDWARD GEDGE, of No. 11, Wellington Street, Strand, London, in the
County of Middlesex, Patent Agent. "IMPROVEMENTS IN SAFETY VALVES OR
SAFETY APPARATUS FOR STEAM BOILERS." A communication from abroad by Emile
Saint Pierre, of Rueil (Seine et Oise), France, Engineer.
It is well known that the safety-valves placed upon steam boilers receive an
additional loading, and it is but rarely that this pressure is obtained in a direct
manner, levers and weights being generally used.
The imperfection and irregularity of the method hitherto used have led to the
Invention of the complete apparatus hereinafter described and shown on the
accompanying Sheet of Drawing, which admits of a direct loading without the aid
of levers or weights, and is termed the
The apparatus is composed of a cast iron box or cylinder P receiving the ordinary
valve A with its seat B, B', and of a cylinder or steam reservoir Q in which moves
the valve A, and which has a conduit at the side cast with it to receive the small
valves e', e', forming steam inlets and outlets for the reservoir Q, a helical spring
g inclosed in a copper case or tube giving pressure on the valve e¹.
The whole is united in one piece, being screwed or bolted together at the joints,
and is fixed upon the steam boiler by a circular strap.
The steam from the boiler arriving by the orifice a enters a circular part or
ring 6, 61, presses upon the annular zone c, c', of the valve A to which it gives a
tendency to lift from its seat B, B', and then passes into another conduit d in the
cylinder C.
The steam coming above the valve A presses it upon its seat B, B¹, and permits
it to be in equilibrium.
To break this equilibrium the pressure of steam continuing to increase has a
tendency to lift the small closing valve e, and close the orifice or conduit d for
admission of steam in to the cylinder C; the steam contained in the cylinder C
escapes by the second valve e¹, so that the ordinary steam escape valve A, meeting
with no further obstacle, lifts and permits the steam to escape by the orifice f
The small valve e' is provided at the top with a helical spring g of steel or of
copper graduated to the normal pressure of the boiler in pounds and fractions
[Price d

page_text: of pounds. (In order to regulate the tension of this small spring in an exact way a
screw tapped copper nut, which may be tightened up or loosened at will, acts upon
this small spring g. Once regulated, the nut is fixed to the screw threaded rod of
the valve e¹ by a pin, so that there is no fraud on the part of the engineer; the steel
spring g might be replaced by a metal weight also enclosed in a similar manner in
a copper box or case.)
The steel spring g yielding to the pressure of the steam tends to lift the small
valve el. When the pressure ceases or lessens the spring g expands again and
resumes its normal position, the small valve e¹ comes down again upon its seat, the
second valve e opens, and the steam again comes above the valve A where the
equilibrium is reestablished.
In case of another excess of pressure the spring g acts again and the same
movements again take place.
As by this arrangement the valve A can rise higher than when levers and
weights are used, the annular section of its opening or lift will be more than
sufficient to give out freely the maximum volume of steam which the boiler can
produce with the most active furnace under the limit of legal pressure.
In locomotive, portable, and marine engines (where weights are unsuitable because
of the shakings or vibrations to which they are exposed during the journey), these
valves are often placed in a group of two upon a support or appendage and as direct
pressure upon the valves cannot be obtained, levers are used, upon the end of which
acts a fine double steel spring enclosed in a copper tube or box. It is this arrange-
ment which is discarded by this Invention, and replaced either by the double
valve (Fig. 2) or by the balance, Figs. 3 and 4, which work exactly as above described.
The balance, Figs. 3 and 4, may be confounded with the heating cocks, as it is
shown on the Drawing.
Figs. 5 and 6 show an arrangement in which the valves are visible; it applies
equally to locomotives, portable engines, and marine engines.
Figure 7 is also an arrangement with visible valves, and differs from that, Figs. 5
and 6, in that the segmental metal piston may be replaced by a closing valve.
It will be evident from the above description, and the Drawings hereunto
annexed, that the construction of the safety apparatus is simple and cheap, that
it is of little bulk, and that it has the advantage of preventing fraudulent or
surreptitious over loading or surcharging, which is always dangerous.