IMPROVEMENTS IN RECIPROCATING AND ROTARY FLUID METERS
Year: 1851

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EDWARD
DUNN, of New York, in the United States of America, but now residing at
Montpelier Square, Brompton, in the County of Middlesex, Master Mariner,
send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of
Great Britain and Ireland, bearing date at Westminster, the Twenty-fourth
day of March (One thousand eight hundred and fifty-one), in the fourteenth
year of Her reign, did, for Herself, Her heirs and successors, give and grant
unto me, the said Edward Dunn, my exors, admors, and assigns, Her
especial license, full power, sole privilege and authority, that I, the said
Edward Dunn, my exors, admors, and assigns, or such others as I, the said
Edward Dunn, my exors, adñors, or assigns, should at any time agree with,
and no others, from time to time and at all times during the term of years
therein expressed, should and lawfully might make, use, exercise, and vend,
within England, Wales, and the Town of Berwick-upon-Tweed, my Invention
of "IMPROVEMENTS IN RECIPROCATING AND ROTARY FLUID METERS;" communi-
cated to me from abroad; in which said Letters Patent is contained a proviso
that I, the said Edward Dunn, shall cause a particular description of the
nature of the said Invention, and in what manner the same is to be performed,
by an instrument in writing under my hand and seal, to be iurolled in Her
said Majesty's High Court of Chancery within six calendar months next and
immediately after the date of the said in part recited Letters Patent, as in

page_text: and by the same, reference being thereunto had, will more fully and at large
appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Edward Dunn, do hereby declare that the nature of the said Invention, and
the manner in which the same is to be performed, are fully described and
ascertained in and by the following statement thereof, reference being had
to the Drawings hereunto annexed, and to the figures and letters marked
thereon, that is to say:-
My Invention consists in a peculiar arrangement and construction of
various parts of rotary and reciprocating fluid meters. In order to point
out fully and clearly such arrangement and construction I will first give
I now
an entire description of each kind of meter as I construct the same.
procced to describe the rotary meter, reference being had to the Drawing.
Figure 1 represents a sectional elevation, and Figure 2 a sectional plan
of this meter. The leading feature of the machine consists in this, that
the fluid to be measured is made to enter and leave a circular channel,
through apertures of precisely equal dimensions, and that in passing through
it imparts motion to a paddle wheel, which moves freely in said channel,
this latter being contracted for about one fifth of the circle. The contracted
part of the channel is made only sufficiently large for the paddles to pass
without touching, whilst the opposite portion is of such dimensions that its
sectional area shall be precisely equal to the area of the contraction added
to the area of either of the apertures through which the fluid enters and
leaves. a, a, the circular channel, and b the contracted portion thereof;
c, c, the paddle wheel, composed of a flat circular disc supported by a cone d,
and revolving on a vertical spindle e, e; f, f, cavities formed in the base
of the machine, into which the fluid first enters through the opening ġ.
h, diaphragm of perforated tin plate, separating the upper and lower portion
of the cavity ff. i, passage leading under a self-acting valve k. 1, chamber
containing said valve. m, the aperture through which the fluid enters the
circular chamber, and n the aperture through which it leaves.
chamber, and P, exit pipe for the measured fluid. 9, pipe communicating
directly with the cavity f. r, a small tangental opening, communicating
with q, and situated near the middle of the paddles. s, cavity formed
in the central part of the machine, closed below by a thin partition t
through the centre of which the spindle e, e, works freely. u, box for
containing an ordinary register. v, pinion on the vertical spindle for com-
municating motion to the register. The machine being supposed to be
charged it will be evident that as soon as the fluid enters the cavity fit
o, exit

page_text: will flow into the circular channel through 7 and r before the valve k
q
opens,
and that. if a very small quantity only be admitted the valve will not open
at all. It will also be evident that if the. jet produced by the fluid entering
through be powerful enough to overcome the friction of the journals of
the wheel this will commence revolving.
The foregoing description being deemed sufficient to show the mechanical
structure and operation of the machine, its properties will next be considered.
Supposing a full current to be passing through, and the wheel revolving, tlie
most striking feature of the operation is the continuous rotation of a definite
quantity of fluid through the contracted channel :b, and its eccentric course
between leaving and entering the same. The next marked feature is the
definiteness of volume passing.a, a. The areas of m and n being alike,
and the area of a being equal to m and b together, the volume passing
a, a, will be equal to the quantity entering at m added to the quantity
returned through 6; and lastly, the quantity leaving n will be equal to the
quantity passing a, a, minus the quantity returned through b. The third
important point is the space passed through in any given time by the paddles
compared to the speed of the current leaving n. The retardation of the
wheel by friction in the journals is so small, when full quantity passes through
the meter, as not to be at all important. Taking this small amount of
friction into account it will be found that the outer portion of the paddles
will move faster than the current entering and leaving, and that the inner
portion will move slower, for the current at m will partially enter the wheel
and partially flow through it, and at n it will partially pass out of the wheel
and partially through it a second time. That an impetus will be given to
the wheel when the fluid passes into and through it is sufficiently evident,
and likewise that a retardation will take place when the fluid passes out of
and through it. Accordingly, neither the inside nor the outside circle
described by the paddles will indicate the velocity of the current at n. Careful
computation would define the mean circle, but the result would not be worth
the trouble. The indication of the register by running a definite quantity
through supersedes the necessity of computation, and the mean thus ascer-
tained will becoine a standard for all meters of like dimensions. The small
jet r is also an important point in the combination of the machine. It might
bė supposed that in passing small quantities through the meter the definite
friction of the journals of the wheel would cause a disproportionate retardation
productive of erroneous iudication. This is entirely obviated by the valve k
and the small jet r. The meter will indicate accurately all quantities sufficient
to supply this small jet, under the pressure produced by the load on the

page_text: valve. The capability to measure smaller quantities than that would not
much enhance the value of the machine for practical purposes; but the
object of the small jet is not only to effect an indication of small quantities,
it also gives vitality to the machine by its ample power to overcome friction
and cause motion. It would be reasonable to suppose that if a sufficient
force were given to this jet to insure positive action of the wheel, an undue
speed, accompanied by erroneous indications would be the result. Not so,
the area of jet is less than Too part of the area of all the paddles. The
counteractive resistance which they offer is according so great that until
the whole mass of 'fluid in the circular channel is put in motion the speed
of the wheel will be scarcely observable. Now, the whole mass cannot move
without producing a current through b and n, for if n be closed the jet at r
ceases, and with it all motion. Again, it may be objected that the inertia
of the wheel will permit a small quantity to pass through before the register
tells. True, but the momentum will on the other hand keep the register in
motion after the entrance of fluid shall have been shut off.
I will now proceed to describe the reciprocating meter. Figure 3 repre-
sents a top view, and Figure 4 a sectional elevation of the machine through
the line X, Y. A, pedestal, in the central portion of which two cylindrical
cavities are formed, and also certain passages or channels through which the
fluid to be measured enters and leaves the machine, as will be hereafter
described. B, semi-circular chamber, with flat ends firmly secured to the top
of the pedestal. C, one of two cylindrical plungers or rams made to work up
and down in the cylindrical cavities a, having water-tight packings at c, c.
made of leather or other suitable material. D, cylindrical boxes inverted over
the plungers, and made to hold down the said packings by bolts d. E, piston
rods attached to the plungers, terminating with lateral forks e, e. F, crank
shaft, terminating at each end with eccentric circular disks f, f, placed at right
angles to each other. G, G, crank pins, secured to the circumferences of said
disks, and also placed at right angles. The diameter of these crank pins
should be considerably less than the opening of the fork e.
H, H, pillar
blocks for supporting the crank shaft, at the same time securing the packings
of the piston rods. J, passage opening into the cylindrical box D, and K
a similar passage communicating with the cavity a. M, ordinary slide
valve. L, exhaust: passage under the slide valve. O, outlet pipe, communi-
cating with the exhaust passage L, as shewn by dotted lines in Figure 3.
N, valve rods, applied to and worked by the eccentric discs f. P, pipe for
admitting the fluid into the semicircular box B. The operation of the
machine is as follows:-The semicircular box being charged, and the fluid.
.

page_text: to be measured permitted to flow in at P, it will, by virtue of bydrostatic
pressure, operate the plungers C by means of the alternating action of the slide
valves over the passages J, L, and K, precicely as the pistons of an ordinary
high-pressure steam engine with double cylinders attached to cranks placed at
right angles would be operated by steam. It is particularly worthy of notice,
that the stroke of the plungers is not regulated by the throw of the cranks,
but by stops r, r, and s, s, placed at definite distances, that bear a certain
relation to the diameter of the plungers, so that each stroke shall displace a
certain definite cubical space. By inspecting the Drawing it will be seen
that owing to these stops the plungers will be brought to a state of rest
before the cranks shall have assumed the vertical position, and that, owing to
the fork of the piston rods being, as before described, wider than the diameter
of the crank pins, these will pass through an arc G, g, both at top and
bottom stroke, whilst the plungers remain stationary, and thereby afford time
for changing the position of the slide valves. The beneficial result secured
by this arrangement will be that the crank pins at no time will have to drag
the plungers, and that the entrance and egress of the fluid to the chambers D
and a, above and below the plungers, is never checked as long as they are in
motion, whilst the stops r and s insure accurate admeasurement at all times
by preserving the definite movement of the plungers, notwithstanding the wear
or slackness of the journals of the crank shaft and irregularity in the throw
of the cranks. A register similar to those of gas-meters being attached, the
quantity of fluid passed through the machine in any given time will be
ascertained.
Having thus described the general character of my Improvements in
Rotary and Reciprocating Fluid Meters, I will now state what I claim in
particular as my Invention in regard to cach.
In the rotary fluid meter I claim,-
Firstly, the uniform circular channel a, a, in combination with the contracted
channel at b.
Secondly, I claim the rotating paddle wheel, having paddles projecting into
and working in the said uniform and contracted channels as described.
Thirdly, I claim the apertures m and n, proportioned and formed as
described.
Fourthly, I claim the pipe q with the jet r, for giving motion to the wheel
before the fluid enters through the aperture m.
Fifthly, I claim the valve K, by which any desirable power of jet may be
obtained before the fluid enters through m.
In regard to the reciprocating fluid meter, I claim as my Invention,-

page_text: . Firstly, the operating, by means of cranks placed at right angles, the two
plungers of definite size by the hydrostatic pressure of the fluid to be measured,
when the operation is combined with definite stops, as described, for regulating
the stroke of said plungers.
Secondly, I claim the forked ends of the piston rods, or similar means, by
which the crank pin is allowed to move through a considerable are in order to
keep the plungers stationary whilst the position: of the slide valves is reversed.
Thirdly, I claim the operating the crank shaft, valve gear, and valves within
the fluid to be measured, in the manner I have described.
In witness whereof, I, the said Edward Dunn, have hereunto set my hand
and seal, this Nineteenth day of September, in the year of our Lord
One thousand eight hundred and fifty-one.