COMMISSIONER'S DECISION
Obviousness: Gas Mask
The apparatus includes a heat exchanger for cooling inhalation air. The
heat exchanger is comprised of a duct which houses a plastic material of low
conductivity. Test information was used to convince the Office that an
unexpected result was achieved by using plastic in lieu of metal in the heat
exchanger. An amended claim was found allowable.
Final Action: Withdrawn - an amended claim accepted.
*******************
This decision deals with a request for review by the Commissioner of
Patents of the Examiner's Final Action dated April 29, 1976, on applica-
tion 188,192 (Class 137-1.52). The application was filed on December 14,
1973, in the name of Wolfgang Eckstein, and is entitled "Respiratory
Apparatus." The Patent Appeal Board conducted a Hearing on March 15, 1978,
at which Mr. I. Makinson represented the applicant. Also in attendance
was Mrs. J. Harding of the same firm.
The application is directed to a respiratory apparatus more specifically
it is a filter-type self-rescue apparatus which includes a heat exchanger
for cooling inhalation gas. The heat exchanger is comprised of a duct
which houses a material of low conductivity. Figure 1 shown below is illus-
trative of that arrangement:
(See formula 1)
In the Final Action the examiner rejected the application in view of the
following British Patents:
1,051,054 Dec. 14, 1966 Auergesellschaft
1,115,349 May 29, 1969 Auergesellschaft
Patent 1,051,054 is directed to a breathing apparatus consisting of a carbon
monoxide oxidation catalyst, a heat exchanger and a mouthpiece; the heat
exchanger is located between the oxidation catalyst container and the
mouthpiece. The heat exchanger is filled with material such as metal wire
or metal wool. Figure 3, shown below, is illustrative of that patent:
(See formula 1)
Patent 1,111,534 is similar to the above discussed patent (same applicant),
but it also includes a means to collect and expel saliva entering the
heat exchanger.
In the Final Action the examiner had, inter alia, this to say:
...
The British patent 1,051,054 teaches a breathing apparatus con-
sisting of a carbon monoxide oxidation catalyst, a heat exchanger
and a mouthpiece; the heat exchanger is located between the
oxidation catalyst container and the mouthpiece. The heat
exchanger is filled with material having good thermal conduct-
ivity, in a manner such that inspired air dissipates its heat to
the said material of good thermal conductivity.
Although not stated in this patent, saliva also enters the heat
exchanger and therefore also acts as a coolant for the inhalation
air in the same manner as that in applicant's device, this is
born out by the British patent 1,115,349 issued to the same
applicant as that of the patent discussed above; this second
patent includes a means to collect and expel saliva entering
the heat exchanger.
The cited patent 1,051,054, therefore differs from the instant
application in that applicant uses, in the heat exchanger,
material of low heat conductivity; the use of material of low
heat conductivity in a heat exchanger however is equivalant
to dividing a flow channel into smaller passages by means of
a material which insulates against radiation or conduction of
heat.
The only means of heat dissipation in applicant's device is
the utilization of moisture such as saliva exhaled and let out
by the user of the breathing device to cool the inhaled air.
Such means of cooling however is inherent in the device dis-
closed by the patent 1,051,054, which is distinctly born out
by the cited patent 1,115,349 both issued to the same appli-
cant, and as discussed above.
Now, since the apparatus in the cited patents is similar to,
and perform its intended task in a similar manner, then it is
held that the instant application does not contain matter of
patentable significance. The mere omission of good heat con-
ducting material in the instant application and the substitution
in its place by material which acts as an insulator to heat
in a heat exchanger is not considered to be of patentable
significance.
The use of moisture exhaled by the user of the breathing apparatus
to cool inhalation air, is also used by the cited patent, in a
manner similar to that in the instant application.
The argument presented by applicant in his letter dated
December 18, 1975, has been considered, however, such argument
does not overcome the above discussed objection.
A reply to such argument as, "a surprising result flows from
the use of material of low thermal conductivity" is discussed
in detail above.
In view of the above discussion, it is held that this appli-
cation lacks in an inventive step, and also the matter disclosed
and claimed by this application is obvious to one skilled in
the art in view of the teaching of the cited reference patent,
hence the refusal of allowing this application to patent is
maintained.
...
The applicant, in his response to the Final Action, added new claims 10
and 11 and stated his position which reads (in part):
...
The incoming air is heated by the catalytic oxidation in the filter
and must be cooled in a heat exchanger before inhalation. The present
invention achieves such cooling by means of a process known as
"evaporative cooling", utilizing the moisture exhaled by the user
as the evaporating medium. It is a well known principle of thermo-
dynamics that heat must be added to a liquid of a given temperature
to convert it to vapour of the same temperature. The heat required
to convert a unit amount of liquid into vapour is called the
heat of vaporization. Thus, it is possible to reduce the tempera-
ture of, e.g., air, by evaporating some liquid in contact with such
air, usually on a large surface, utilizing the heat content of the
air to provide the heat of vaporization of a liquid. Such process may
be described as a process of "evaporative cooling".
In the apparatus of the present invention, moisture from the
exhaled air is deposited, by condensation or otherwise (possibly
fine droplets) on the relatively large surface of the material
contained in the heat exchanger. Any heat of condensation (the physical
opposite of heat of vaporization) is carried away by the exhaled
air and thus removed from the system. At this point, the significance
of the requirement that the material contained in the heat exchanger
be of low thermal conductivity may be firstly observed. Namely, if
any heat is liberated by any condensation of the water content of
the exhaled air, such heat will not be conducted into the interior
of the filler material but will remain at the surface available
to be transferred to the exhaled air. When hot air is inhaled into
the heat exchanger, the liquid contained on the surface of the heat
exchanger is evaporated and the inhaled air is cooled by the removal
of the heat of vaporization as described above. Due to the relatively
large surface of the material contained in the heat exchanger, the
effect of the evaporative cooling is pronounced. It is critical to
the proper function of the evaporative step that the material contained
in the heat exchanger be of low thermal conductivity in order that
it does not carry the heat contained in the inhaled air into its
interior and store it as a heat sink but allow such heat to remain
at the surface to be available to vaporize the liquid thereon.
...
The applicant does not agree with the examiner's assertion that
"the use of material of low effect conductivity in a heat exchanger....
is equivalent to dividing the flow channel into small passages by
means of a material which insulate against radiation or conduction
of heat". The crucial reason why the present invention employs a
material of low thermal conductivity in the heat exchanger is to pre-
vent a significant flow of heat from the surface to the interior of
such material. The reason for this is two-fold. Firstly, it is
undesirable that the material in the heat exchanger act as a heat
sink and accumulate the heat from the inhaled gas and, secondly, the
present invention requires that the surface or surfaces of the
filler material and the heat exchanger, but not its interior, be raised
to a fairly high temperature during the inhalation of the hot gas,
so that the saliva previously condensed or otherwise deposited thereon
evaporates and, so that its heat of vaporization results in cooling
of the inhaled air as fully explained above.
The question before the Board is whether or not the applicant has made a patent-
able advance in the art. Our first consideration will be to determine whether
or not a patentable invention has been described in the application as filed.
This must be determined from the advance made over the teachings of the cited
art.
On a complete study of the application we find that there are a number of
differences. It appears that the applicant has taken the known method of evap-
orative cooling and incorporated it into a device not suggested by the
cited art. e.g. there is no teaching of a heat exchange chamber filled with
plastic material in the form of wires, chips, screens, granules, balls or
tubes.
Mr. Makinson argued that the present device is patentable because, inter alia,
it gave unexpected results in tests carried out in comparison to known apparatus.
In view of our hesitancy in deciding whether an invention is described, we
decided, after the Hearing, to request a copy of the test results to analyse
them to see what the improved or unexpected results were. This was submitted
by the applicant on April 28, 1978. It is in the form of a test report, dated
September 6, 1972, which sets out the results of a comparison of respiratory
apparatus of the present invention with that of the prior art. The tests were
carried out by "Development and Constructions - FILTERTECHNIK" and they indicate
that by using the conventional construction, with a spun metal material in the
housing, the inhaled air was cooled to 57.degree.C, while the present apparatus,
using a plastic granulate in the housing, cooled the air to an average of
about 50.degree.C. We note that the tests on the present apparatus was carried out
with plastic materials only in the heat exchanger.
In view of the above considerations we are satisfied that an invention has been
described in the disclosure, because the applicant devised an apparatus which
performs in an unexpected, improved or more expeditious manner.
On a complete review of the claims we are not satisfied that they distinctly
define the scope of monopoly of the invention commensurate with what, in our
view, is the invention described in the disclosure, and for which the test
results were provided. For example, claim 1 merely defines over the cited
art by stating that the material of the heat exchanger is of low thermal conductivity.
We believe that a claim drawn along the following lines would be acceptable.
Claim 1:
A filter respirator for self-protection against carbon
monoxide and which has a catalyst portion which operates
at high temperatures and a mouthpiece casing portion which is
operable to cool respirated air by the evaporation of the user's
saliva, comprising a catalyst casing having an air inlet and an
internal passage filled with a catalyst material, and a mouth-
piece casing connected to said catalyst casing with passage
means for a flow of air from the catalyst casing through said
mouthpiece casing, said mouthpiece portion casing containing
an internal heat exchanger chamber filled with a plastic
material of low thermal conductivity in the form of wires, chips,
screens, granules, balls or tubes, through which the exhaled
air is passed so that the saliva adheres to the material and
the subsequent inhaled air is cooled by the evaporation of the saliva,
and an exhalation valve connected to said passage means downstream
of said passage means with respect to exhalation gas flow.
This claim is essentially claim 8 of the present claims, but the scope of
monopoly of the invention is defined in more explicit terms.
To summarize, we are satisfied that a patentable advance in the art has been
made and we recommend that the decision in the Final Action to refuse the applica-
tion be withdrawn. We recommend that proposed claim 1 be accepted along with
any other appropriately dependent claims.
J.F. Hughes
Assistant Chairman
Patent Appeal Board, Canada
I have reviewed the prosecution of this application and agree with the recommend-
ation of the Patent Appeal Board. Accordingly, I withdraw the Final Action, but
I refuse to accept the present claims. I will, however, accept the claim proposed
by the Board. The applicant has six months to cancel the present claims, submit
an appropriate amendment, or to appeal my decision under the provision of
Section 44 of the Patent Act.
J.A. Brown
Acting Commissioner of Patents
Dated at Hull, Quebec
this 19th. day of May, 1978
Agent for Applicant
Fetherstonhaugh & Co.
Box 2999, Station D
Ottawa, Ont.