An Improved Apparatus for Indicating Air-draught for Ventilating and other Purposes.
Year: 1894

page_text: Date of Application, 12th Jan., 1894-Accepted, 14th Apr., 1894
COMPLETE SPECIFICATION.
An Improved Apparatus for Indicating Air-draught for Ventilating
and other Purposes.
1, HERMANN RECKNAGEL, Engineer, of 7 Schaffhauser Strasse, Winterthur,
Switzerland, do hereby declare the nature of my invention and in what manner the
same is performed to be particularly described and ascertained in and by the
following statement :-
The present invention consists of an apparatus for indicating the air draught,
for use in connection with ventilating systems to indicate any variation in the
draught and in case the latter should exceed or drop below a certain desired
standard, to report such irregularity to any desired part of the building.
The apparatus is constructed on the principle of that class of anemometers.
having a sensitive blade or plate which is actuated by the draught and the invention
consists mainly in the means employed to regulate or adjust the blade to indicate
any required draught and variations in such desired "standard" draught and also
in certain means, herein after more particularly described, to increase the moment
of inertia of the spindle and hand actuated by the said blade or plate, and thus,
obtain a steadier motion of the parts, which would otherwise move too suddenly
into one or other of the extreme positions, thus continually reporting a merely
momentary variation of the draught and giving rise to unnecessary inconvenience.
In order to enable an apparatus of this kind to report variations in the draught to
different parts of the building a steady motion of the parts is absolutely necessary;
and it is owing to the want of this steadiness, that the ordinary anemometers are
inapplicable for the purpose, since their light weight and momentary sensitiveness.
cause a continual making and breaking of the circuit and unnecessary alarm.
The present apparatus, which is particularly applicable for schools, hospitals
and in fact for all buildings having ventilating systems, has the great advantage,
that on a change in the speed of the air current taking place the blade and pointer
or hand perform the corresponding movement almost without further oscillation, so
that the hand is always steady on the dial and the condition of the air draught can
be read off at any time.
And in order to make the present Specification more easily intelligible reference
is had to the accompanying drawing in which similar letters denote similar parts
throughout the several views:
Fig. 1 being a perspective diagrammatic view showing the general arrangement.
of the parts of the apparatus,
Fig. 2 a vertical section through the apparatus,
Fig. 3 a front elevation with the cover open and broken away and
Fig. 4 a complete front elevation.
The spindle a, which carries all the moveable parts of the apparatus, is mounted
on the points of the screws ss at the top of the standard 6 fixed in the casing B
of the apparatus, as shown at Fig. 2. To the front end of this spindle a are
attached the pointer or hand z and the adjusting and balancing mechanism, herein.
after more particularly described, whilst the opposite end extends out of the casing
nto the air channel and carries the blade or plate f, which is advantageously made
of aluminium and must be perfectly rigid. The apparatus should be fixed in a
vall of the air channel in such manner as to be easily removeable, for instance a
ing A may be bricked in the said wall and the apparatus fitted into the ring and
eld in place by means of screws or in any other suitable manner (Fig. 2). The
asing B is closed at the back by a plate C having a sleeve through which the
pindle a passes, said plate serving to keep out dust and dirt. The front of
he casing is closed by the dial D and hinged glass front after the manner of a

page_text: clock. The dial may be suitably graduated and is advantageously marked “weak,"
"normal" and "strong."
"
is
The adjusting and balancing mechanism, which serves at the same time to
increase the moment of inertia of the moveable parts of the apparatus, consists of
the adjustable weights g h and mounted respectively on the arms g h and i
of the spindle a. Of these three weights, h¹ serves to counterbalance the weight
Both g' and h¹
of the plate fand is mounted diametrically opposite to the same.
are adjustable on their respective rods which are threaded for the purpose.
revoluble on the arm j of the rod i and excentrically weighted at it, thus the same
may be adjusted by turning it on its pivot ; and removing its centre of gravity
nearer to or further from the centre of the spindle a. The weight should fit its
pivot sufficiently tightly as to enable it to remain in any position into which it is
turned, or a suitably arranged spring may be employed to increase the friction.
In order to adjust the apparatus in the first place, the eccentric weight should
be turned into position nearest to the centre of the spindle a and the weight gl
adjusted to counterbalance it, so that the whole mechanism is balanced and will
remain in any position stationary. By turning the disc with the eccentric
weight on its pivot j, the equilibrium will be destroyed and the weight tends
to swing the plate fin the opposite direction to the current of air which is to be
controlled, coming in the direction indicated by the arrow in Fig. 1. The pointer
or hand z is mounted on the spindle at an angle of 45 degrees to the plate ƒ and
the weight should be adjusted to allow the hand to show "normal" on the dial,
when the required strength of current is playing on the plate f. From this it
will be clear that by varying the position of the weight, the apparatus can be
adjusted to any required strength of current, which will then keep the pointer at
"normal." In order to adjust the apparatus to a certain known current, an
ordinary anemometer should be employed in combination with the same and the
weight adjusted until the pointer = shows "normal" when the current of air
indicated by the anemometer is playing on the plate f. Any variation in the said
current will then be indicated by the pointer which on a decrease of current will
move towards "weak" and on an increase towards "strong" on the dial.
2
situated
This motion of the pointer may be employed to make and break electric
circuits in the following manner :-
A very flexible flat spring is arranged a little distance above the weight ¹
as shown at Figs. 1 and 3. To one end of this spring is attached a circuit wire r
whilst at a suitable distance from the point of attachment of the spring two
contacts p and q are arranged respectively a little above and below the spring.
The lower contact o normally-i.e. when the spring is not raised by the weight i
touches the spring completing the circuit rq whilst the upper contact p
"norinal" current
slightly above the said spring. When now the pointer shows a
the spring will be lifted from the contact 9 by the disc (Fig. 3) but if the
draught exceeds the normal strength, the said spring will be raised still higher
and, lifted by the weight or disc i, will make contact with p, on the other hand if
the draught drops below the normal, the said spring will be released by the disc
and fall down onto the contact a completing the circuit q'r. The conductors can
be taken to the superintendent's room or to other convenient part of the building
so that any irregularity will be reported at such point. The contacts p and q are
connected to the contact screws 1 and 2' (Fig. 3) whilst 3 is in communication
with the spring v.
The apparatus can be used in connection with any air passages whether vertical,
horizontal or at an angle, as it will only be necessary to arrange the angle of the
plate to correspond..
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is performed I declare that what I
claim is :-
1. An air draught indicating apparatus having a spindle a mounted in antifriction

page_text: hearings, and having at one end a plate or blade factuated by the air draught and
at the opposite end a pointer z, suitable weights on said spindle to counterbalance
the said plate and pointer and increase the moment of inertia of the moveable part
and an adjustable weight to adjust the apparatus to any required draught
substantially as described.
2. An air draught control apparatus having a spindle a mounted on points s s', a
standard 6 to carry said spindle, a plate or blade fat one end of said spindle to
extend into the air passage, a pointer at the opposite end of said spindle, an
arm with adjustable weight to counterbalance the plate f, an arm i with
weighted disc and adjustable weight, an arm g with adjustable weight g¹
and a suitable dial D in the manner and for the purpose substantially as
described.
3. In combination with an air draught indicating apparatus having a spindle a
mounted in antifriction bearings and having at one end a platef and at the other a
pointer z, suitable weights on said spindle to counterbalance the said plate and
pointer and increase the moment of inertia of the moveable parts and an adjustable
weight, a flexible spring to extend horizontally over the adjustable weight,
and having conductor and contacts and 9 above and below said spring in the
manner and for the purpose substantially as described.
4. An air draught indicating apparatus having a spindle a mounted in points s s¹,.
a standard b to carry said spindle, a plate or blade fat one end of said spindle to
extend into the air passage, a pointer z at the opposite end of said spindle, an
arm h with adjustable weight h¹ to counterbalance the plate or blade f, an arm
with weighted disc and adjustable weight 1, an arm g with adjustable weight g¹
and suitable dial D for the said pointer, a flat spring mounted in the casing and
extending horizontally over the disc, contacts p and q above and below said
spring and suitable electric connections substantially as described and shown and
for the purnose specified.
1004
Dated this 12th day of January 1894.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.