IMPROVEMENTS IN SAFETY VALVES
Year: 1876

page_text: LETTERS PATENT to Robert Findlay, of Glasgow, in the County of Lanark,
North Britain, Engineer, for the Invention of "IMPROVEMENTS IN SAFETY
VALVES."
"
PROVISIONAL SPECIFICATION left by the said Robert Findlay at the Office
of the Commissioners of Patents on the 20th April 1876.
ROBERT FINDLAY, of Glasgow, in the County of Lanark, North Britain, Engineer
IMPROVEMENTS IN SAFETY VALVES."
This Invention has reference generally to a new or improved construction of
safety valves for steam boilers, but suitable also for air or other fluid high-pressure
generators, magazines, or holders, which valves, from their said peculiar construction,
act or open and close more sensitively and efficiently at or near their "set" or
initial regulated escape or load pressure with about half the dead load weight (or
strength of spring when that is used) on then required for the other ordinary direct
or dead loaded valves in general use.
And the particular construction (or nature and novelty of the said Invention or
valves) consists all as follows:-In having the valve duplex, that is, with a small
internal lifting valve on a central lid, disc, or boss with its seat on the upper ór
outer side of the seat of the larger or safety valve proper, and with its stem, pre-
ferably strong and cylindrical, working and guided in the centre of the said seat
below, and in or up and out through the eye and hollow stem of the lifting valvo
or lid, part of the said large safety valve seat carrying the whole. This large valve
is made as usual of a size, or with a lift and escape area, sufficient for the size or
generating power of the boiler to which it is fitted, but of the annular equilibrium
double beat or faced class, with lifting outer ring or hollow cylindrical case,
working over guide feathers across and springing up from the seat (set as usual in
the lower part of the valve chest) with close cap above, so that the outer case
closes on a narrow face at its lower edge on the outside of the seat, and a like seat
on the inside of its upper edge on the close cap of the seat above the guiding feathers,
which may be three, four, five, or six in number, according to the size of the valve,
the steam escaping up through between e feathers in volume sufficient to relieve
the pressure within the boiler under any possible workable conditions, out
through the sides below the close top and the outer working ring case or valve

page_text: when raised, and also in sufficient volume through between the said arms or
feathers at the centre below the lid of the small initial lifting valve on the central
solid spindle, with its seat in a shallow cylindrical recess in the middle and top of
the close top of the main valve seat, as to lift it at the regulated internal boiler
pressure desired, to which this small initial acting valve is loaded in the usual
manner on the top of its spindle by a weight or spring (above the hollow spindle of
the main valve or it might be on the lower stem within the boiler), that is, with
pound for pound to the square inch of area of the small valve up to the pressure
required. This regulated initial acting, or regulating opening and closing valve
only opens a sixteenth of an inch or so before it acts on the under side of the
central arms and eye of the lifting opening case of the real escape or safety valve,
which really forms the counteracting force to its further lifting by the confined
pressure and steam within the boiler, which cannot at first escape by the small lift
and slightly closed cylindrical form of its face, so that the small valve lifts the large
one by this accumulating pressure of steam applied to it. Thus the large valve,
being nearly equilibrium, only requires to be loaded by a weight or pressure spring
against this confined increasing pressure (on its hollow spindle above the arms and
below the bushed lubricating cover or other guide on the valve chest) proportionate
to the difference of the area between its faces and on the area of the small valve, so
that a weight of not more than half of that usually required is found to be sufficient
with an apparently proportional superior and sensitive action with less risk of
derangement or breakage.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Robert Findlay in the Great Seal Patent Office on the 20th October
1876.
ROBERT FINDLAY, of Glasgow, in the County of Lanark, North Britain, Engineer.
"IMPROVEMENTS IN SAFETY VALVES."
"
My said Invention has reference generally to a new or improved construction of
supply valves for steam boilers, but suitable also for air or other fluid high-pressure
generators, magazines, or holders, which valves from their said peculiar construction
act or open and close more sensitively and efficiently at or near their "set"
or initial
regulated escape or load pressure with less than one-half of the dead load weight (or
strength of a spring when that is used) on them than is required for the other
ordinary direct or dead weight loaded valves in general use, with apparently a
superior or more sensitive action both in opening and closing at little variation from
the regulated pressure, and with less risk of derangement or breakage.
And in order that the nature, novelty, and mode of performing my said Invention
may be properly undertood, I shall now proceed to describe the several Figures on
the Sheet of Drawings which I have hereunto appended for the purpose of showing
the best modes and means I am at present aware of for putting the Invention into
effect or practice, the same reference letters indicating the same or like parts in all
the Figures where shown.
Figure 1 is a sectional elevation of my new or improved duplex safety valve a, a¹, a¹¹,
A, A³, constructed in accordance with and illustrative of one modification or arrange-
ment of my said Invention adapted for land or marine steam boilers, fitted much in
an ordinary manuer within a close case and sole B, B¹, secured to a branch stool C,
to be bolted by the flange C to a convenient part of the steam boiler, not shown in
the Drawing, B2 being the blow-off pipe for the escaping steam. In this case the
central spindles a² and A2 of the moving lids of the valves a, a¹¹, and A pass out
through a guide bush in the cover B₁ of the chest B, the weights W of the large
valve A being mounted over its spindle A2 within the chest B, and the spindle a² is
carried up outside the chest with a cap 6 mounted on it, which carries the spiral

page_text: pressure spring w, retained above by the pressure cross bar 6¹ and screw nuts 611,
carried by the screw standards B11 secured to the cover B". The pressure required
on the small valve a, a¹¹, is given in this case by the strength of the spring w, tem.
pered or adjusted by the pressure nuts b, securing the bar b' to the columns B
Figure 2 shows a side elevation of the movable part A of the large or main valve,
and Figure 3 shows an elevation of its seat A', both detached.
Figures 4 and 5 are respectively a sectional elevation and plan partly in section
of one arrangement of this new or improved safety valve with two sets of the valves
both loaded with weights, the one set being free and open to the admosphere, and
capable of being actuated by a hand lever D, while the other set is all enclosed
within a close locked chamber B, and specially suitable for marine boilers.
Referring to these Figures 1, 2, and 3, the nature and novelty of this Invention
or particular construction of the valve and mode of putting the same into effect or
practice consist all as follows:-In having the valve duplex, that is, with a small
internal lifting valve face a forined on a central lid disc or boss all of the central
spindle a, and its seat a¹ in the centre of the upper and outer dished crown or
top A of the hollow fixed scat A' of the larger lifting or escape safety valve A
proper, and having its stem a² preferably strong and cylindrical, with the lower
part working and guided through a central eye in the cross arms A111 of the said
seat A¹ below, while the longer top stem a² works similarly up or out through the
eye or hollow central stem A³ of the arms at the hollow or annular double face or
beat valve or lid part A of and working over the said large safety valve seat A¹,
fitted and fixed fluid tight by a flange or otherwise in an ordinary manner to the
bed B¹ of the steam chest B, and carrying the whole working parts and weights, as
seen in the sectional elevation, Figure 1, and in Figure 4.
The large valve A is made as usual of a size or with a lift and escape area
at A3, A3, sufficient for the size or generating power of the boiler to which it is to
be fitted, but of the annular equilibrium double beat or faced class; with the lifting
outer ring or hollow cylindrical case A working over the guide cross arms or
feathers A springing up from the seat A¹, and supporting the close crown or
cap A above, with the outer case closing on a narrow face at the lower outer edge
of the valve A and seat A¹, and a like seat on the inside of their upper edges both
at A3, A3, the latter close over the top A¹ of the seat A, above the said guiding
cross feathers A", which may be three, four, five, or six in number, according to the
size of the valve, the steam escaping up through between the feathers A¹¹ in
volume sufficient to relieve the pressure within the boiler under any possible
workable conditions, out through the sides below the outer working ring case or
valve A and the close top at A³ when raised, and also in sufficient volume through
the said arms or feathers A" at the centre a¹ below the lid a, a, of the small.
initial lifting valve on the central solid spindle a with its seat a' in a somewhat
larger shallow cylindrical recess a¹ in the middle of the close top A¹ of the main
valve seat A', as to lift it at the regulated internal boiler pressure desired, to
which the small initial acting valve a, all, is loaded, all as indicated by the arrows.
The valve a, a, is loaded by a spring w mounted on the top of its spindle a² (but
it might be by a weight w, as in Figures 4 and 5), carried up above the hollow
spindle A carrying the load weight W of the main valve A (or it might be on the
lower stem within the boiler), that is, with pound for pound to the square inch of
area of the small valve and seat a, a, up to the pressure required. This regulated
initial acting or regulating opening and closing valve a, a¹¹, only opens a sixteenth
of an inch or so above its chamber a when it acts at a³ on the under side of the
central arms and eye of the lifting opening case A or large loaded escape safety
valve proper, which at first forms a counteracting force to the further lifting of the
small valve a, a¹¹, or escape of the confined pressure and steam within the boiler,
which thus accumulates while acting on the slightly enlarged close cylindrical
face a¹¹, so as to cause the small valve a, all, to lift the large one A.
The large
valve being annular with narrow faces, as before stated is nearly equilibrius, and
therefore only requires to be loaded by the weight W in pounds, equal to that of

page_text: the confined accumulating pressure required to open the two valves, nearly pro
portionate to the difference of the area in inches closed in by the faces at As, a, of
these valves, and that of the small valve a loaded by its own spring or weight w
adjusted and tested by trial and error in each case.
Referring to the double arrangement shown in Figures 3 and 4, the construction
of the valve proper A, A¹, A", A¹¹¹, and its small initial acting valve a with its
enlarged upper ring a fitted on the central seat a¹, all, are all substantially the
same as described in reference to and shown in Figures 1, 2, and 3, except that the
small valve spindle a² is loaded with a weight w¹, and the chest seat B₁ and bench
stool C, C¹, are made double, with a valve and fittings mounted over each; the
one to the left having the chest B made high enough to enclose the whole with a
cross guide b² for the spindle A2, all as suitable for a locked valve at fixed pressures
which cannot be tampered with. The arrangement to the right is left open and
has strong pillars B projecting up from the seat B¹ with cross bars 61, 62, at top
for guiding and steadying the spindles a² and A2 of the valves secured by screw
nuts 11. A forked lever D is jointed at D¹ to one of the columns B with its
forked ends D acting on the under side of the collar A* of the spindle A², carrying
the weights W of the large valve A, so as to raise these and blow-off or relieve the
pressure of steam in the boiler by the long arm D2 of the hand lever D at will, and
which may have a hook as at D1, to which a counterweight or a chain may be
attached for that purpose.
Although the lid of the small valve a, a, is shown as a disc valve on the centre
of its spindle, it is to be understood that it might be made in the form of a ball,
either with or without a rim all round it, in which case the enlarged chamber a¹¹i
would be made deeper than shown in the Drawings to reach the sides of the
ball.
Having now described the nature of my said Invention and the manner of
performing or putting it into effect or practice, I have to state that I do not confine
myself to the precise details herein described or delineated, but what I consider
novel and original, and therefore clain as the Invention secured to me by the
herein-before in part recited Letters Patent is,―
First. The construction and use of duplex safety valves for steam boilers and
other like purposes, substantially as herein described in reference to and shown in
the accompanying Drawings, or any mere modification thereof.
Second. The construction of a duplex safety valve for steam boilers and other
like purposes, in which the small valve a with enlarged rim a works in a recessed
seat a, a, in the top A of the seat A¹ of the large annular double faced valve A,
substantially as herein described in reference to and shown in the accompanying
Drawings, or any mere modification thereof.
In witness whereof, I, the said Robert Findlay, have hereunto set my hand and
seal, this Sixteenth day of October, in the year of our Lord One thousand
eight hundred and seventy-six.