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Патент USA US2408052

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Sept. 24,‘ 1946.
K. o. DONELIAN
2,408,051
FIRE AND SMOKE DETECTOR AND THE LIKE
Filéd Agsril 4, 1942
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INVENTOR
K. O. DONE LIAN‘
‘Ni/QM
ATTORNEY
Patented Sept. 24, 194E
2,408,05l
UNITED STATES PATENT OFFICE
2,408,051
FIRE AND SMOKE DETECTOR AND
THE LIKE
Khatchik 0. Donelian, New York, N. Y., assignor
to American District Telegraph Company,
Jersey City, N. J ., a corporation of New Jersey
Application April 4, 1942, Serial No. 437,615
13 Claims.
This invention relates to ?re detecting and
alarm apparatus, and more particularly to an
(01. 177—311)
2
unit comprises also a second chamber contain
ing spaced electrodes which is shielded against
electrical detecting unit and system responsive
the admission of ionized air particles and con
to the presence of combustion products and/or
tains a quantity of a radioactive material to im
smoke in the atmosphere adjacent the detector
UK part a normal conductivity characteristic to the
unit.
space between the electrodes. It is found that
The object of the invention is to provide an
the presence of smoke particles in the air in said
improved and highly sensitive ?re detecting unit
space impedes the progress of the alpha radiation
which responds to minute traces of either ionized
from
the radioactive material and thereby re
combustion gases or suspended solid particles
duces the amount of ionization of the air pro
having no electrical charge, generally referred 10 duced
by said radioactive material. The effect
to as smoke particles.
‘
of the smoke particles is therefore the opposite
Another object of the invention ‘is to provide
of the ionized air particles, and the shielding
a combined ?re and smoke detector of the ioniza
means is employed to prevent ionized air par
tion type which will respond either to ?res that 15 ticles, if present, from masking the e?ect pro
produce little or no smoke, such as those involv
duced by the smoke particles.
ing organic combustibles like alcohol or gasoline,
In accordance with a further feature of the
or to ?res that produce only smoke with little or
invention, the electrodes and source of potential
no perceptible heat or ?ame.
are connected in the input circuit of a vacuum
A still further object of the invention is to
tube ampli?er or other electrical relaying means
simplify and improve the construction of an 20 in such a manner that the electroconductive ef
electrical detector unit and alarm system of the
fects of the two elements of the detector are
class described.
‘
,
combined additively so that, if both ionized air
Hitherto ?re detecting apparatus which depend
particles and smoke particles are present in the
upon detection of the by-products of combus
atmosphere adjacent the detector unit, the effect
tion have included smoke detectors embodying 25 is somewhat greater than if only the ionized
optical measuring apparatus or gas detectors
particles or only the uncharged particles are
employing chemicals to detect speci?c gases,
present.
such as carbon monoxide or carbon dioxide, usu
For a better understanding of‘ the invention
ally formed in the combustion process. These
reference may be had to the accompanying draw
prior devices have been relatively complicated,
ing showing a preferred embodiment thereof, and
as well as unsuitable or unreliable for many ap
in which:
plications, and have required considerable super
Fig. 1 is a sectional view of the detector unit
vision and maintenance, such as the periodic re
taken on the line l--! of Fig. 2;
‘ placement of exhausted chemicals or parts.
35
Fig. 2 is a side elevational view of the detector
The present invention is based upon the well
unit with a portion of the outer shell broken
known fact that the by-products of combustion
away; and
may contain ionized molecules or particles, as
Fig. 3 is a circuit diagram of the detector unit
well as solid smoke particles which have no elec
connected in a typical alarm circuit.
trical charge. It is also known that the ionized 40 Referring to Figs. 1 and 2 of the drawing,
molecules or particles may retain for several
a preferred form of the detector unit, drawn to
minutes or more their ionized characteristics so
about three-quarter scale, comprises an outer
that the conductivity of the gas containing said
perforated metallic shell or electrode It) par
molecules for a considerable period of time is
tially or completely enclosing two spaced inner
substantially different than that of air at the 45 electrodes II and i2, and acting as an electro
same temperature. Accordingly, the detector
static shield for the elements enclosed therein.
unit in its preferred form includes means such
The top of the hollow or cup-shaped electrode
as spaced electrodes upon which a predetermined
l0 may be closed by an insulating cover or cap
l5 serving as a support for lead-in conductors
detect the presence of the ionized molecules or 50 l6 and the vacuum tube ampli?er H, as shown.
potential diiierence is maintained in order to
particles. However, this would not provide for
detecting the presence of suspended smoke par
ticles in the atmosphere, which sometimes occur
without the ionized air particles or molecules.
Accordingly, the preferred form of the detector
The vacuum tube I1 is substantially enclosed by
the electrode i2 which also acts in conjunction
with an intermediate partition, I8 to divide the
spaces bounded by the electrodes ill, I! and it’
into the three chambers 22, 23 and 24, ‘all of
2,408,051
4
which are open ‘for circulation of combustion
gases and smoke from a ?re in the vicinity of the
detector unit.
Chamber 22 is employed for the detection of
ionized air particles since the presence of such
particles in the space between electrodes iii and
.
although the ionized air particles increase the
conductivity of chamber 22 and the smoke par
ticles decrease the conductivity of chamber 24, the
change in potential of the grid 2| of the vacuum
tube is in the same direction in each case so
that there is no tendency for one e?ect to com
pensate or cancel out the other but rather the
combined effect results in quicker response to a
?re. As shown in Fig. 1, the inner electrode 5?.
the detector unit connected to the control elec
completely enveloped by chamber 23 and by the 10 of
trode or grid 2| of the vacuum tube ampli?er
imperforate insulating members 15 and i8 so that
extends into both chambers 22 and 24 of the
all of the air and gases circulating through cham
detector unit, and the electrodes Ill and H are
ber 24 must ?rst pass through the outer cham
connected to the positive and negative terminals,
ber 23, for reasons which will be explained below.
respectively, of the» source of potential. This is
The inner chamber 24 contains a quantity‘ of
represented diagrammatically in Fig. 3, in which
radioactive material 2% which normally ionizes
12a and IE1) represent the two parts of the elec_
the air in said chamber to a ?xed degree. How
trode
l2, and the spaces between said electrodes
ever, the presence of solid smoke particles in sus
and electrodes ii] and H represent the chambers
pension in said air impedes the alpha emana
through which combustion gases and smoke par
tions from the radioactive material 28 and thus *
ticles circulate in the event of a ?re. A source of
reduces the conductivity of the space between
potential impressed upon the electrodes. of: the
electrodes H and i2 so long as smoke is present.
unit is represented by the battery 25. In order
In order to prevent ionized air particles and the
to secure the proper cathode-grid bias, depend
like, which may be contained in the air currents
around the detector unit, from nullifying the . ing upon the characteristics of the tube ll, a
second source of potential 26 may be connected, ‘
effect. of smoke particles in reducing the con~
for example, in the, cathode circuit of said am
ductivity of the air or gases in the inner cham~
pli?er. A normally deenergized alarm. relay 2%
ber 24, the electrodes IE3. and ii are maintained
and a normally energized trouble relay 29, are
at a suf?ciently high di?erence of potential to
shown by way of illustration, as connected in
de-ionize the circulating gases entering chambers
i2 causes a variation in the conductivity charac
teristic of said space. On the other hand, cham
ber 24 bounded by the electrodes H and I2 is
23 and 24.
The voltage impressed between elec
‘ the, plate circuit of’ the vacuum tube, ampli?er
trode it and electrode II, for example, may be
100 volts, since a potential gradient of the order
of ‘L0 or 50 volts per centimeter is su?iciently high
to neutralize the charges on any charged par
ticles in a slowly moving air current. In this
manner, the charged particles are ?ltered out of
Ill. The contacts of relay 2.3I'are arranged to
control a buzzer or alarm device 30,. whereas the
contacts of the relay 29 are arranged. to operate
a similar trouble signal 3.! in the event that the
plate current of the ampli?er H drops below its
normal value, as would be caused by failure of the
battery, breaking of. the connecting conductors
the. air currents entering chamber 21;, while the
or failure of the vacuum tube itselii.
smoke particles suspended in the air will enter
Under normal conditions, the. potential of the
chamber 2!; and reduce the ionization in said 4.0 grid
2! of the vacuum tube ampli?er H is main
chamber as. described above.
tained at a predetermined potential,7 by reason
It will be apparent from the foregoing descrip
of the connection of said grid tothe, terminals
tion that either the ionized-particle detecting
of the battery 25 through, the resistances repre
element. or the smoke detecting'element of the
sented
by the spaces between; the. electrodes Ill
45
detector unit shown in Figs. 1 and 2 may be used
and‘ lZa, and H and I21), respectively. This po
tential is preferably so chosen with respect; to
that ofthe cathode; that the, ampli?er-7H‘ is con
simple and effective manner is the preferred
ductive and‘ the plate current thereof. is, sui?cient
construction. It will also be apparent that the
con?guration and arrangement of the electrodes 50 to maintain the cont-acts of the trouble relay 2.9
open but insu?icient to operate the,‘ marginal
may be widely varied without departing from the
alarm relay 28. If‘, however, the conductivity of
operating requirements outlined above, which re»
independently, although the arrangement shown
in which the two elements are combined in a
. the space between the electrodes H1 and, l2a; is
increased, owing to the presence of ionized air
chamber and the smoke detecting chamber be
open to the air for circulation of the by-products 55 particles to, which the, detector unit is responsive,
the potential of the grid. 2|; of the ampli?er ll
of combustion from the ?re therethrough; and,
becomes more positive, and; the, increased plate
second, that the chamber containing the radioac
current of the ampli?er actuatcs the'contacts of
tive material must be shielded against the ionized
relay
28 to sound the alarm 3!}. Similarly; it the
air particles. The radioactive substance 2Q may
conductivity
of the space between the electrodes
be a ceramic ?lm containing radium or some ra 60
H and lZb decreases» upon the occurrence of
dioactive salt. Reference is made to this mate
smoke in said space, the grid 2 l» of‘ the, ampli?er
rial because it may be purchased in this form in
ll likewise becomesv more positive than before,
the open market but other forms may be substi
and thus the alarm relay 2.8; is operated either
tuted. For the preferred arrangement shown in
quire-?rst, that the ionized-particle detecting
Fig. 1, approximately one microgram of radium 65 upon the occurrence of ionized air particles or
of smoke particles in the combustion gases from
.in ceramic ?lm fonm described above is used.
In accordance with a further feature of the
invention, the electrodes and the source of cur
rent are so connected to the input circuit of a
vacuum tube ampli?er H or other relaying means 70
that the opposite electroconductive effects in
the two detecting chambers are additively com
bined. In this manner, if the by-products of
the ?re, and the electroconductive' effects are
additive when both conditions occur simultane
ously. Therefore, it will be seen that thedetector
unit will respond. to either so-called smokeless
?res or to ?res which produce. smoke with
no perceptible ?ame» or heat, as Wel_1_as to ?res
in which considerable ?ame and smoke are both
produced.
combustion from the ?re include both ionized air
particles and solid smoke particles in suspension, 75 ' While the vacuum tube ampli?er I1 shown in
5
2,408,05 l.
Fig. 3 is a triode, any high gain pentode ampli?er
of the 38, 606 or other type may be used, provid
ing its input or grid resistance is very high. It
has generally been found desirable to reduce the
‘filament voltage impressed to approximately 60%
of the rated normal value to reduce positive ion ,
emission to a negligible value in order to obtain
this high grid resistance. It is also to be noted
that, although only one stage of ampli?cation is
shown, additional stages may be provided if de
sired, depending upon the operating current re
quirements of the control relays.
‘one of said electrodes being common to two of
said spaces, a vacuum tube having the control
electrode thereof connected to said last-mentioned
electrode and means having said vacuum tube and
said electrodes as parts thereof for detecting the
presence of ionized air particles in one of said
two spaces and smoke particles in the other.
5. A detector unit for ?re alarm systems com
prising a plurality of spaced electrodes de?ning
spaces open to the atmosphere for circulation of
combustion products from a ?re therethrough, a
While no special mounting arrangement or
‘vacuum tube connected in a manner to be con
smoke comprising spaced electrodes de?ning two
in with an additive control effect upon the pres
trolled by variations in the electroconductive
positioning of the detector unit is required in
characteristic of one of said spaces, means for
many installations, conventional means, such as 15 normally ionizing said one of said spaces to a
sampling pipes, may be employed to direct com
predetermined degree and means for shielding
bustion gases and smoke from distant ?res to
the same against entry of ionized air particles
the detector unit. Various other modi?cations
whereby the conductivity of said space is varied
and auxiliary arrangements will occur to those
skilled in the art and may be employed without 20 by the presence of smoke particles therein, said
vacuum tube also being connected in a manner
departing from the scope of the invention as
to be controlled in the same manner by the elec
de?ned in the appended claims.
' troconductive characteristics of another space
I claim:
caused by the presence of ionized particles there
1. A detector unit for detecting either ?re or
separate chambers through which pass the com 25 ence simultaneously of smoke particles and
ionized particles in the respective spaces.
bustion products from a ?re in the space to be
6. A detector unit for ?re alarm systems com
protected, means to maintain a difference of po
prising at least three spaced electrodes de?ning
tential between said electrodes, and detection
adjacent spaces exposed to combustion products
means having as parts thereof a pair of said elec
trodes to detect a changejn the conductivity of 30 from a. ?re in the space to be protected, the said
product including either ionized molecules or
the gases in one of said chambers resulting from
solid particles in suspension in the form of smoke,
ionized air particles or molecules reaching said
or both ionized molecules and smoke particles, 2.
chamber from a ?re, said detection means hav
source of potential connected to said electrodes,‘
ing as part thereof a third electrode cooperating
with one of said pair of electrodes to shield the 35 means for ionizing the air in the space between
two of said electrodes, and means so co-acting
other of said chambers from ionized molecules,
with said electrodes as to detect jointly and sev
said third electrode cooperating with the other
erally by electroconductive eiiects smoke particles
of said pair of electrodes to detect smoke par
in suspension in the ionized air between two of
ticles in suspension in the air or gases in said
40 said electrodes and‘ionized molecules in the air
other chamber.
.
in another of said adjacent spaces between two
2. A detector unit for detecting smoke compris
of said electrodes.
ing at least three nested electrodes de?ning two
'7. A detector unit for ?re alarm systems com
chambers‘ or cavities open to the atmosphere, one
of said chambers being enveloped by the other,
a quantity of radioactive material in said one
chamber, means having two of said electrodes as
parts thereof for neutralizing charged or ionized
particles from the air or gas in the other cham
ber whereby the air or gas circulating through
the chamber containing radioactive material is
free from charged particles except as produced
by such material and means having two of said
electrodes as parts thereof for detecting changes
in conductivity of the air or gas in said one cham
ber upon the occurrence of smoke particles sus
pended in the air or gas therein.
3. A detector unit for ?re alarm systems com
prising at least three spaced electrodes de?ning
adjacent spaces exposed to combustion products
from a ?re in the space to be protected, the said
products including either ionized molecules or
solid particles in suspension in the form of smoke,
or both ionized molecules and smoke particles,
a source of potential connected to said electrodes,
means for ionizing the air in the. space between
two 'of said electrodes, and means so col-acting ‘
with all of said electrodes as to detect by elec
troconductive e?ects smoke particles in suspen
sion in the ionized air between two of said elec
trodes and ionized molecules in the air in another
of said adjacent spaces between two of said elec
trodes.
prising a plurality of spaced electrodes de?ning
8. A detector unit for ?re alarm systems com
at least two spaces in inner and outer relation
and open to the atmosphere for the circulation 60 prising spaced electrodes exposed to combustion
products from a ?re in the space to be protected,
of combustion products from a ?re therethrough,
the said products including either ionized mole
an inner one of said spaces ple?ned by two of said
cules or solid particles in suspension in the form
electrodes being completely enveloped by a space
of
smoke, or both ionized molecules and smoke
between two of said electrodes, said inner space 65
particles, 3, source of potential connected to said
containing means to ionize the gas therein to a
electrodes, means so co-acting with all of said
predetermined degree, means to deionize gaseous
electrodes
as to detect ionized molecules between
combustion products prior to entering said inner
a pair of said spaced electrodes and uncharged
space, and means having the electrodes de?ning
smoke particles in suspension between a third
the inner space as parts thereof for detecting
electrode and one of said pair of electrodes and
smoke particles in said inner space.
‘
a common biasing control circuit included in said
4. A detector unit for ?re alarm systems com
means and so connected to one of said electrodes
prising spaced electrodes de?ning a plurality‘ of
that said means is affected by both ionized mole
spaces open to the atmosphere for circulation of
cules and smoke particles in suspension from ?re
combustion products from a ?re therethrough, 75 producing combustion products containing both.
552,408,051
9.. A detector unit for detecting either ?re or
smoke comprising at. least three spaced electrodes
de?ning two separate chambers through which
pass the combustion products from a ?re in the
space to be protected, means to maintain a dif
ference of potential between. said electrodes and
means co-acting with all of said electrodes to
detect ionized air particles or molecules in one
the. vacuum tube, and means having said elec
trodes and said tube as parts thereof for detect
ing variations in the conductivity path between
said electrodes.
l
12. A detector unit for ?re alarm systems com
prising spaced electrodes de?ning a plurality of
adjacent spaces. open to the atmosphere for cir
culation of combustion products from a ?re there
through, means. for ionizing the atmosphere in
of
chambers and uncharged smoke particles
one of saidtspaces, a source of potential connected
in the other chamber by electroconductive effects, 10 to said electrodes, and a vacuum tube ampli?er
said electrodes being so associated each to the
" connected to said electrodes to be controlled in
other and to. said means as to additively combine
the same manner by the variations in the con
effects when both ionized molecules and un
ductivity of said spaces resulting either from
charged particles are present.
10. A detector unit for ?re alarm systems com 15 smoke particles. 'to the substantial exclusion oi
transient ionizedv air particles in a space of ionized
prising at least three electrodes de?ning cham
atmosphere or from ionized air particles to the
bers open to the atmosphere for circulation of
substantial exclusion of smoke particles in an‘
combustion products from a ?re therethrough, a
vacuum tube having its control element con
nected. to one of said electrodes, a source of po
tential so connected to said electrodes and to said
vacuum tube that each electrode is at a different
potential from that of each of the other elec
trodes, means for. ionizing the air in one of said
other of said spaces, with an additive control ef
fect upon simultaneous changes in the conduc
20 tivity of said spaces.
7
13. In a ?re alarm system, a vacuum tube am
plifier provided with a control electrode‘, a detector
unit connected to said control electrode, means
ionizing the atmosphere in a part of said unit,
chambers, and» means including said electrodes, _-25 for
and means in said unit to vary the potential of
vacuum tube, and source of potential for detect
said electrode in'the same direction upon the oc
ing variations in the conductivity of the space
currence of either smoke to the substantial ex
paths of the respective chambers resulting from
clusion of transient ionized air particles, in a part
di?erent types of combustion products in the re
of said unit having ionized atmosphere or of
spective chambers.
'
11. A detector unit for ?re alarm systems com "so ionized air particles to the substantial exclusion
of smoke in another part of said unit, and to vary
prisingv cup-shaped perforated shell electrode,
the potential , of said electrode upon the oc
a second hollow electrode inside of the ?rst-men
currence. simultaneously of both ionized air par
tioned electrode and spaced therefrom, a vacuum
tube supported inside of said second electrode and 1:35 ticles and smoke in said unit, said last-mentioned
having the control element thereof connected to
the second electrode, a. source of potential con
nected to the two electrodes and to the anode of
potential variation being an additive function of
the separate variations.
,
KHATCHIK O. DONELIAN.
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