Improvements in Valves Applicable for Automatically Shutting off Steam in Case of too Free Emission, as from the Fracture of a Pipe or the Slipping of the Main Driving Belt.
Year: 1888

page_text: Date of Application, 8th Sept., 1888
Complete Specification Left, 27th May, 1889-Accepted, 29th June, 1889
PROVISIONAL SPECIFICATION.
Improvements in Valves Applicable for Automatically Shutting off
Steam in Case of too Free Emission, as from the Fracture of a
Pipe or the Slipping of the Main Driving Belt.
I, JOHN HAMILTON BRAIDWOOD of 214, West Street, Crewe, in the County of
Chester, Engineer; do hereby declare the nature of this invention to be as follows:-
Many very serious accidents have occurred with marine and other steam engines
owing to a pipe bursting.
This invention is designed to stop the passage of steam through the steam pipe,
should such an accident occur. In a turned valve chamber in the steam pipe
immediately beyond the stop valve I place a valve, preferably vertical, and have one
seat above or beyond it in the direction in which the steam passes. This valve, when
up to its face, entirely closes the passage of the main steam pipe; in order, however
to prevent the valve sticking in this position after it has once closed, I forn a passage
from below the seat to a point above the seat, which passage is controlled by a
small subsidiary valve. I also arrange a special knocking or pressing device so that
the main valve can be knocked or pressed from its seat at any time. But I should
preferably so arrange it that it will be impossible for the valve to be permanently held
from its seat. The knocking or pressing device can, however, be superseded by an
arrangement for temporarily causing less pressure above the valve than beneath it.
The mode of action is as follows:
Whenever the stop valve is opened in ordinary course, that is gradually opened,
and so long as the steam passes in ordinary flow, so long will the steam pass around
the valve head and through the valve seat. The moment, however, a sudden escape
or usage of steam takes place, so as to occasion great reduction of pressure above
the valve, the latter closes and is held closed by the pressure of the steain below it.
When the occasion of the abnormal escape of steam is rectified, the small hand
valve can be drawn back and thus admit steam above the valve. If the valve does
not immediately fall, but sticks to its seat, the knocking device is used, or a vacuum
or momentary reduction of pressure is formed in the steam valve below the main
valve. The main valve now falls back, leaving a free course to the steam. The
knocking device can be used at any time, should the valve close through racing or
other temporary cause.
Dated this 7th day of September 1888.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Patent Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Valves Applicable for Automatically_Shutting off
Steam in Case of too Free Emission, as from the Fracture of a
Pipe or the Slipping of the Main Driving Belt.
I JOHN HAMILTON BRAID WOOD of 214, West Street, Crewe, in the County of
Chester, Engineer, do hereby declare the nature of this invention and in what manner
the same is to be performed, to be particularly described and ascertained in and by
the following statement :-
Many very serious accidents have occurred with marine and other steam engines
owing to the bursting of a steam pipe.
This invention is designed to stop the passage of steam through the steam pipe,
should such an accident occur.

page_text: In the drawings accompanying this specification:-
Figure 1 is a sectional elevation of the valve for automatically shutting off steam.
Figure 2 a cross section on line a 6 Figure 1.
Figure 3 an elevation of the valve alone.
In these, A is a bored valve chamber, preferably placed in proximity to and just
beyond the stop valve, and connected to the steam pipe B by flanges a a. In the..
chamber A aforesaid, I place a valve C, preferably vertical, and having a valve seat D
above or beyond it, in the direction in which the steam passes. This valve, when up
to its seat, entirely closes the passage of the main steam pipe B. In order to prevent
the valve sticking in this position after it is once closed, I form a passage E from
below the seat D to a point above the said scat, which passage is controlled by a
small subsidiary valve operated by the screwed valve spindle G and hand lever H.
I also arrange a
knocking or pressing device, so that the main valve C can be
knocked or forcibly pressed from its seat. It comprises a cam or eccentric I which
is received by a groove c in the valve C, and is adapted to lift the valve on to, or
towards its seat D and thereby close or partly close the passage for the steam, or to
draw it away therefrom so as to open the steam passage. The cam is rotated by a
spindle and hand lever J.
The mode of action is as follows:-
Whenever the stop valve is opened in ordinary course, that is, gradually opened,
the steam will pass into the pipe B and onwards past the lip of the valve C to the
engine. The moment, however, a sudden escape or usage of steam takes place, so as
to occasion undue reduction of pressure above the valve C, the latter closes and is
held closed by the pressure of the steam below it.
When the cause of the abnormal escape of steam is rectified, the small band valve F
can be drawn back and thereby admit steam above the valve C so as to equalise the
pressure, and allow the valve to drop.
If the valve C does not immediately fall, but sticks to its seat D, the knocking or
pressing device I is used to break contact between the valve and its seat, thereby
leaving a free course to the steam. The knocking device I can be used at any time
should the valve C close through racing or other temporary cause.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is.:
1. The improvement in automatic shut off valves of the kind described for
preventing a sudden escape or usage of steam, which consists in connecting the
steam space above the valve seat with that below it by means of a passage controlled
by a subsidiary valve operated at will from the exterior, whereby the pressure on each
side of the main valve may be equalized, after the sudden escape or usage has been
rectified, such subsidiary valve and passage being employed either with or without a
device for forcibly detaching the main valve from its seat, substantially as and for the
purpose described.
2. In combination with an automatic shut off valve of the kind described, a rotatable
cam or eccentric I engaging a device such as groove c in the valve, and adapted to
lift the said valve towards or onto its seat, or forcibly draw it away therefrom,
substantially as and for the purpose described.
Dated this 24th day of May 1889
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Patent Agents for the Applicant.