IMPROVEMENTS IN APPARATUS FOR REGULATING THE FLOW OF FLUIDS
Year: 1876

page_text: LETTERS PATENT to Fleeming Jenkin, of 3, Great Stuart Street, in the City
of Edinburgh, for the Invention of "IMPROVEMENTS IN APPARATUS FOR
REGULATING THE FLOW OF FLUIDS,"
the Sth August 1876, and dated the 28th February 1870.
PROVISIONAL SPECIFICATION left by the said Fleeming Jenkin at the Office
of the Commissioners of Patents on the 28th February 1876.
FLEEMING JENKIN, of 3, Great Stuart Street, in the City of Edinburgh.
PROVEMENTS IN APPARATUS FOR REGULATING THE FLOW OF FLUIDS."
"IM-
The object of my Invention is to regulate the flow of fluids in such a way that
either a constant flow shall be maintained through a given pipe, or a constant
pressure shall be maintained in it as may be desired.
If the constant flow is required I admit the fluid into a chamber A by an equi-
librium valve of simple construction. The chamber A is separated from a second
chamber B by a horizontal partition through which a vertical plunger connected
with the equilibrium valve works freely. When the plunger is at the bottom end
of its range the valve is open, when it is at the top the valve is shut, and at inter-
mediate points the valve acts as a throttle valve, reducing the flow as the valvo
rises.
The position of the plunger depends on the difference of pressure between A.
and B, the difference of pressure multiplied into the area of cross section of the
plunger gives the total force tending to lift the plunger. When this force is equal
to the weight of the plunger the latter remains poised in equilibrium; if the
difference of pressure increases the plunger rises, throttles the fluid so as to reduce
the pressure in A, and assumes a new position of equilibrium. The difference of
pressure may be caused by an increase of pressure outside the valve or by a decrease
of pressure in the chamber B; the effect is the same in both cases. Quite similarly
if the difference of pressure decreases the plunger and valve fall so as to diminish
the throttling action. The difference of pressure between A and B is therefore
maintained constant within such limits as are within the control of the throttle
valve. A constant sized opening is provided between A and B, and through the
constant opening the constant difference of pressure will produce a constant flow.
Thus the head on either side of the valve may vary within wide limits, and by it
the flow past the valve will remain constant. The opening between A and B may

page_text: be the annular space round the plunger so as to diminish the friction. In any case
it may be made adjustable so that any desired flow may be obtained.
When constant pressure beyond the valve is desired instead of constant flow I
cause the rise and fall of an equilibrium valve by the expansion or contraction of a
closed vessel under the pressure. Preferably for liquids I employ a closed metallic
vessel with corrugated sides. The buoyancy of this vessel when compressed by the
desired intensity of pressure in chamber B is just sufficient to carry the weight of
the plunger. Any diminution of pressure causes the vessel to expand and rise.
This rise opens the valve which is now placed so as to separate the chambers A
and B. This rise diminishes the throttling, and the valve remains in a new position
of equilibrium under the same pressure as before.
Both forms of apparatus are applicable both to fluids and gases.
When the flow
is small and the variations of pressure moderate the valves in some instances need
not be equilibrium valves in either form of apparatus, as the disturbance produced
by variations of pressure on a very small area may be insignificant.
To regulate a pressure of a gas the compressible chamber must be contained in a
vessel full of liquid, such as water, oil, or mercury.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Fleeming Jenkin in the Great Seal Patent Office on the 28th August
1870.
FLEEMING JENKIN, of 3, Great Stuart Street, in the City of Edinburgh.
PROVEMENTS IN. APPARATUS FOR REGULATING THE FLOW OF FLUIDS."
"IM-
The object of my Invention is to regulate the flow of fluids in such a way that
either a constant, flow shall be maintained through a given pipe, or a constant
pressure shall be maintained in it, as may be desired.
If the constant flow is required I admit the fluid into a chamber A by an equi-
librium valve of simple construction. The chamber A. is separated from a second
chamber B by a horizontal partition through which a vertical plunger connected
with the equilibrium valve works freely. When the plunger is at the bottom end
of its range the valve is open, when it is at the top the valve is shut, and at inter-
mediate points the valve acts as a throttle valve, reducing the flow as the valve
rises.
The position of the plunger depends on the difference of pressure between A
and B, the difference of pressure multiplied into the area of cross section of the
plunger gives the total force tending to lift the plunger. When this force is equal
to the weight of the plunger the latter remains poised in equilibrium; if the
difference of pressure increases the plunger rises, throttles the fluid so as to reduce
the pressure in A, and assumes a new position of equilibrium. The difference of
pressure may be caused by an increase of pressure outside the valve or by a decrease
of pressure in the chamber B; the effect is the same in both cases. Quite similarly
if the difference of pressure decreases the plunger and valve fall so as to diminish
the throttling action. The difference of pressure between A and B is therefore
maintained constant within such limits as are within the control of the throttle
valve. A constant sized opening is provided between A. and B, and through this
constant opening the constant difference of pressure will produce a constant flow.
Thus the head on either side of the valve may vary within wide limits and yet the
flow past the valve will remain constant. The opening between A and B may be
the annular space round the plunger so as to diminish the friction.
may be made adjustable so that any desired flow may be obtained.
In any case it
When constant pressure beyond the valve is desired instead of constant flow I
cause the rise and fall of an equilibrium valve by the expansion and contraction of
a closed vessel under the pressure. Preferably for liquids I employ a closed metallic

page_text: vessel with corrugated sides. The buoyancy of this vessel when compressed by the
desired intensity of pressure in chamber B is just sufficient to carry the weight of
the plunger. Any diminution of pressure causes the vessel to expand and rise.
This rise opens the valve which is now placed so as to separate the chambers A
and B. This rise diminishes the throttling, and the valve remains in a new position
of equilibrium under the same pressure as before.
Both forms of apparatus are applicable both to fluids and gases. When the flow
is small and the variations of pressure moderate the valves in some instances need
not be equilibrium valves in either form of apparatus, as the disturbance produced
by variations of pressure on a very small area may be insignificant.
To regulate a pressure of a gas the compressible chamber must be contained in a
vessel full of liquid, such as water, oil, or mercury.
Having thus described the nature of my Invention I will proceed to describe
more fully the manner of performing the same.
Figure 1 shows a simple form of the valve adapted to give a constant flow. The
liquid, say water, arrives by the branch C and fills the space surrounding the equi-
librium valve D. It passes to the chamber A by the double passage, as shown by
the arrows.
From A the water passes through the aperture and in small
quantities round the plunger P which works easily in the web W; finally the water
is delivered through the branch E. The plunger P and valve D are in equilibrium
when the difference of pressure per square inch in A and B is such that this
difference multiplied into the area of the cross section of the plunger P is equal to
the weight of the plunger and valve as immersed in the liquid. If there is a greater
difference of pressure P and D rise and the flow of water past D and through O is
diminished, and consequently the difference of pressure between A and B is
diminished until equilibrium is reached. If the difference between A and B is
smaller than that consistent with equilibrium, P and D fall, increase the flow, and
consequently increase the difference of pressure until equilibrium is reached. Thus
a constant difference of pressure is maintained between A and B and gives a
constant flow through the constant opening between A and B. This constant
opening might be replaced by an annular space round P, in which case the
plunger and valve would require to be guided by a central spindle.
Figure 2 shows an axample of this construction adapted for gas when the plunger
is made very light.
Figures 3, 4, and 5 show a design adapted for a large flow of water. Corre-
sponding parts have the same letters as in Figure 1. The opening O may in this
design be varied by the sluice valve. A given constant flow will correspond to
each position of the valve. The plunger P is made very light so that there may be
the least possible loss of head or throttling at O. The part of the discharge pipe B
which is near O, the chamber B, and the connecting pipe B all fulfil the part of
the simple chamber B in Figure 1, the pressure in these parts being sensibly equal.
The equilibrium valve employed in all cases is a simple cylindrical valve without
seats, such as might in its simplest form, Figure 1, be made by filing away part of a
cylinder into a form of triangular section. The valve is therefore only a throttle
valve and is not adapted for closing the passage hermetically. A great advantage
of this form is that the gas or water never has to flow between two closely con-
tiguous surfaces where accretions might take place clogging the action of the valve.
To avoid all risk of this kind I prefer to limit the play of the valve so that the solid
cylindrical part never enters the guiding holes where in the usual equilibrium valve
there would be seats.
Figure 6 shows the valve by which I maintain constant pressure in a chamber
through which the liquid is flowing. The liquid, say water, enters by pipe C and
passes through an equilibrium valve, similar to that already described, into the
chamber A; it leaves this chamber by the pipe E. The equilibrium valve is carried
by a compressible float F. When the pressure in.A increases the float is compressed,
its displacement is diminished, the float and valve consequently sink until the flow
is so much diminished that the pressure in A is also diminished to that point at

page_text: which the displacement of E is just sufficient to let the system F and D remain in
equilibrium, neither rising nor falling. F would be in unstable equilibrium if by
falling, say, one inch, and throttling the flow at D it did not cause the pressure to
diminish at a rate greater than that by which the pressure in the chamber A
increases per inch. This remark would hardly be necessary if the pressure in A
was always considerable relatively to the range of the float F and valve D, but in
those cases where it may be desirable to maintain only a small pressure beyond A
the point is one of importance. In the first description of the valve it was assumed
that the pressure in the chamber A might be assumed to be practically constant at
all points, but it is clear that if the range of the valve is, say, 6 inches, the float
will be subjected to a head of pressure 6 inches greater when at the bottom of its
range than it was subject to when at the top of its range. In those cases where
a head of 6 inches of the liquid constituted a material difference the valve in
question would not be useful, but by diminishing the range the difference due to
this cause may be reduced so as to be of no importance in most cases arising in
practice.
I construct the float, by preference, of corrugated metal chambers similar to those
used for aneroid barometers. An air cock must be provided at the top of the
chamber if this is so constructed that air can accumulate in the neighbourhood of
the float.
In the arrangement described the valve and float are very free to move, there
being no stufling box or other cause of friction.
When used to regulate the pressure of a gas the float must be submerged in a
liquid of considerable density, such as water, and the surface of the liquid must be
subject to the pressure of the gas which is to be controlled. The Invention is not
however suitable for the control of very small pressures owing to the change of
pressure alluded to above as resulting from a deeper immersion of the float in the
liquid. This change becomes sensible when the total pressure is small, as is the
case, for instance, in the gas mains used for house supply.
I claim,―
First. The constant flow valve, being the combination described of the equilibrium
valve D with the plunger P, the chambers A, B, and the entrance and exit pipes
C, E. I am well aware that the principle according to which the valve regulates
the flow has been applied by Leslie and by Girond, but Leslie's arrangement is
imperfect by reason of the omission of the equilibrium valve, and Girond's is
imperfect by reason of the imperfection of the equilibrium valve suggested, whereas
the equilibrium valve used in my combination is easily constructed, and is accurately
equilibrated, and is not subject to be clogged by deposit.
Secondly. I claim the constant pressure valve described, being the combination
described of a closed compressible wholly submerged float with the equilibrium
valve described, the chamber A, and the entrance and exit pipes C, E.
In witness whereof, I, the said Fleeming Jenkin, have hereunto set my
hand and seal, this Twenty-fourth day of August, in the year of our Lord
One thousand eight hundred and seventy-six.
DT BRING
TENKIN
FLEEMING JENKIN.
(i..S.)