AU463559B2 - Burning and collection apparatus for combustion gas - Google Patents

Description

53 18 /n This invention rela es to a burning and is used collection apparatus for combustion gases, which in analyzing the composition of the combustion gases such as plastics, generating upon burning a sample material the combus- by burning the sample material and collecting tion gases. In recent years, building fire in which many It human lives are lost is one of the social problems. others, is said that such casualty is caused by, among plastic the toxic gases generating by the combustion of materials, such as carbon monoxide, hydrogen cyanide, etc. hydrogen chloride, phosgene, carbonyl sulfide, It. is, therefore, desired to selectively use plastic into materials for particular applications while taking which account the composition of the combustion gases fire. each plastic material will generate at the time of burned The combustion gases generated when a material is the contain gases which are generated by the burning of by material with flames and gases which are generated accom- the thermal decomposition of the material without panying flames. Thus, it is necessary, in determining from the composition of the combustion gases generating the a plastic material at the time of fire, to determine compositions of both types of gases. Many reports have

f been made Qwe~ g1 the composition of the gases which

are generated when plastic materials are subjected.to thermal cracking in an inert gas atmosphere or under reduced pressure, but few reports have been made concern- when ing the composition of the gases which are generated plastic materials are burned or subjected to chemical

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53018/7n change accompanying light andheat. Conventional burning and collection apparatus used for the composition analysis of combustion gases are classified broadly into the following types: I. A type in which a sample material is burned in the atmosphere and the resulting combustion gases are collected in a large container disposed above the sample material by taking advantage of the ascending and dissipa- tion of the combustion gases. II. A type in which a sample material is heated by an electric heater in a flask having air or an inert gas such as nitrogen gas sealed therein, and the resulting gases are collected in the flask and a balloon connected to said flask for relieving the pressure building up in said flask. III. A type in which a sample material.placed in a magnetic boat with an iron piece attached thereto is inserted in a combustion tube, located at a heating portion in said combustion tube by shifting said magnetic boat externally by means of a magnet and burned at said heating portion in air or an inert gas, such as nitrogen gas, introduced into said combustion tube at a predetermined rate, and the resulting combustion gases are collected in a flask which has previously been reduced in pressure. However, the apparatus of the type I has had the disadvantages that the composition analysis cannot be achieved with high accuracy since the combustion gases are diluted with a large quantity of air, and that the combustion is possible only in air and the atmospheric gas cannot be changed optionally. The apparatus of the type

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53, 018/73 when the material II has suffered the disadvantage that sealed air, the is burned in the flask in which is decreases as the oxygen concentration in the flask built up in said flask burning proceeds and pressure is is inflated, so by generated gases though the balloon material under the that it is impossible to burn the end of the burning. same conditions from the start to had the disadvantages The apparatus of the type III has rate of air or inert that the regulation of the supply pressure in the flask is gas relative to the decreasing conditions can hardly difficult and hence the combustion if the supply rate of all be maintained constant, namely under pressurized or inert gas is too high, combustion if the supply rate state will result while conversely, pressure state will is too low, combustion under reduced the combustion conditions result, and that, therefore, of combustion though vary between the start and end in the apparatus of the not to such a large degree as

type II. is to An. object of the present invention apparatus which attempts provide a burning and collection prior art apparatus. to overcome the problems of the

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According t'one sect of the present invention

there is provided a burning and collection apparatus for

combustion gases, comprising combustion means having a

combustion chamber for burning a sample material received

therein and a heating furnace for heating the sample

material in said combustion chamber to a predetermined

and adjustable combustible temperature, gas supply means

for leading to an inlet of said combustion chamber air

or other gas at a predetermined and adjustable rate,

dehumidizing means for removing moisture from the

combustion gases existing through an outlet of said

combustion chamber by cooling said combustion gases and

thus condensing an aqueous vapor contained therein, gas

collection means having a cylinder for receiving the piston combustion gases from said dehumidizing means and a

slidably fitted in said cylinder, said piston being means provided on its outer periphery with seal ring said which is in light contact with an inner surface of piston cylinder, and driving means for displacing said of at a predetermined and adjustable rate in a direction

sucking the combustion gases into said cylinder. According to a further aspect of the present

invention there is provided a burning and collection

apparatus for combustion gases according to Claim 1, lined wherein the inner wall surface of said piston are

with coating films of plastic materals little reactive

with the combustion gases to be collected in said

cylinder.

The combustion chamber is made preferably of and materials which do not react with combustion gases

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53.018/ The heating highly resistive to heat, e.g. quartz. or gas burning furnace may be of electric heater type preferred in view type, but the elctric heater type is of the heating of stability and easiness in adjustment

temperature, and sanitation. As the gas supply unit, in the atmosphere an air pump or the like is used when air nitrogen or oxygen is to be supplied, or means for mixing

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53.018 /73 gas in air is used when an air of oxygen concentration

different from that of the atmospheric air is to be used, or a bomb containing an inert gas, such as nitrogen gas, is used when such inert gas is to be used. However, the atmospheric air is generally used in the operation of the. subject apparatus and, therefore, the apparatus will be described hereunder.as comprising an air supply unit. The air supply unit is roforably of a type by which the supply rate of air per unit time can optionally be adjusted and which is capable of supplying air at a stable rate. Such type of air supply unit includes an air pump, a blower and a bomb. Further, when the atmospheric air is to be supplied, it' doeirablo to provide dehumidization

means/in the air supply line on the downstream side of the combustion chamber so that water-soluble gases in the combustion gases resulting from combustion may not dissolved in water contained in air. The piston-cylinder

type gas collection unit mayfbeeLof a type in which a piston is moved or a cylinder is moved with the piston fixed, for sucking the combustion gases generated in the combus- tion chamber. The piston or cylinder may be operated 'either manually or by an operating device. It is essential,

however, that the quantity of air supplied per unit time by the air supply unit and the quantity of gases sucked per unit time by the gas collection unit be substantially equal so as not to create a pressurized condition or reduced pressure condition in the combustion chamber, or to maintain said combustion chamber at normal pressure condition. To this end, an operating device, such as motor, is generally used to operate the piston or cylinder

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53018/7 at a constant speed. The piston or cylinder operating device, similar to the air supply unit, is p-er-e.by of a type by which the suction rate of gas can optionally be adjusted. However, even with such operating device, it is extremely difficult to make equal exactly the supply rate of air and suction rate of gas. Therefore, the dimensions of the piston and cylinder are selected preferably so as to provide therebetween sealing effect to such a degree that, when a pressure differential has occurred between the interior and exterior of the cylinder upon displacement of either the piston or cylinder relative to each other, air may move into the cylinder to eliminate the pressure differential, whereas when a pressure diffe- rential has not occurred, the movement of air may be blocked, and thereby to maintain the suction rate of gas slightly larger than the supply rate of air. If the suction rate of gas is simply made slightly larger than the supply rate of air, a reduced pressure condition will appear in the combustion chamber. However, by selecting the dimensions of the piston and cylinder as described above, a slight amount of air flows into the cylinder as the internal pressure of the cylinder tends to decrease below the atmospheric pressure at the time of suction operation, whereby the development of sub-atmospheric pressure in the cylinder and combustion chamber can be prevented and substantial dilution of the collected gases can be avoided, and further the adjustment of the operat- ing speed of the operating device can be facilitated. The inner walls of the cylinder and piston which are contacted by the combustion gases should be coated with

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53 A18 73 materials little reactive with the gases, e.g. fluorine- containing resin and polyethylene, or the cylinder and piston should be made of such materials, so that said inner walls may not be attacked by the combustion gases. Water-soluble combustion gases may be generated occasionally depending upon the type of sample material burned. If

the aqueous vapour generated in the combustion chamber on such occasion are collected in the cylinder along with other combustion gases, the water-soluble gases will be dissolved in the water formed in the cylinder upon cooling of the aqueous vapour. Thus, the gases insoluble in water will be collected in the gaseous state and the gases soluble in water in the form of solutions in water, so that the subsequent analysis of gas composition cannot be completed at once. It is, thererore, recommendable to provide between the combustion chamber and gas collection unit cooling means for cooling the gases to be collected and liquefying the aqueous vapour entrained therein, and thereby to remove the water from the gases so as not to be collected in the gas collection unit. As the cooling

means, a conduit connecting the combustion chamber with the cylinder may be elongated so that the aqueous vapour may be cooled and condensed by the external air during passage in said elongate conduit. It is possible to

contact cold water with the outer surface of the conduit to forcibly cool and condense the aqueous vapour. Further, it is advantageous for enhancing the accuracy of analysis, to provide filter means in the conduit between the combustion chamber and cylinder to remove smoke and soot from the combustion gases before they are collected

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in the cylinder. fully understood from The present invention well be more embodying the invention taker Sthe following detailed description drawings in which: in conjunction with the accompanying layout of an embodiment Fig. 1 is a diagram showing the for combustion gases, of the bruning and collection apparatus

according to the invention; unit of the Fig. 2 is a sectional view of the combustion the temperature o apparatus, showing the arrangement to measure

said combustion chamber; type Fig. 3 is a sectional view of the pistoncylinder

gas collection unit; and unit. Fig. 4 is an end view of thdgas collection invention will be des- Now, an embodiment of the present

cribed with reference to the drawings. In the drawings, reference numberal 1 designates materials such as plastics ax a comubstion unit in which sample

be burned, the combustion unit 1 includes a quartz-made and a heating furnace 3 cylindrica -combustion chamber 2 2 externally. The combust: surrounding said combustion chamber 46 mm and a height of 220 no chamber 2 has an inner diameter of gas inlet port 4 extendin< bnd is provided at its bottom with a 3 and at its top with a outwardly through the heating furnace 7 which is opened and outlet port 5 and a sample supply port

closed by a cap 6. Quartz beads 8 are filled in the combustio the bottom of said.chamber chamber 2 up to a level 75 mm from diameter of 60 mm and a The heating furnace 3 has an inner heater height of 200 mm, and is provided with an electric

Namely, the heating furnace 3 is of,so-called therein.

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9 designates an electric heating type. Reference numeral port 4 of air supply unit for supplying air to the inlet the combution chamber 4.

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53. 018/73 of a This air supply unit 9 consists of an air pump type in which the supply rate of air per unit time is adjustable, and is connected to the inlet port 4 by a gas supply passage 10. Reference numeral 11 designates a dehumidization unit provided in the gas supply passage and consists of a tank 12 with desiccants such as silica gel 13 disposed therein. A section of the gas is opened supply passage 10 leading from the air pump 9 in the bed of silica gal 13 and another section of said gas supply passage 10 leading to the combustion chamber 2 is extended from the top of the tank 12 spaced above the bed of silica gel 13. In the gas supply passage

on the downstream side of the dehumidization unit 11 is provided a flow meter 14 which indicates the quantity of air supplied to the combustion chamber 2 in a unit time. Reference numeral 15 designates a piston-cylinder type gas collection unit for collecting the combustion gases generating in the combustion chamber 2. This gas collec- tion unit 15 consists of a cylindrical cylinder 17 communicating with the gas outlet port 5 of the combustion chamber 2 through a gas exhaust passage 16, and a piston 18 disposed in said cylinder 17 for sliding movement therein. The cylinder 17 has a cross-sectional area of 177 cm2 and an internal volume of 4 1, and is made of stainless steel. The inner wall of the cylinder 17 is lined with a coating film 19 of a material little reactive with the combustion gases collected, e.g. polytetrafluoro- ethylene or polyethylene. The piston 18 is provided with

a rope-shaped seal ring 20 which is made of a tetrafluoro- ethylene having a Shore hardness of 50-65 and mounted on

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53.018 /n

with thereof in light contact the outer peripheral surface cylinder 17. The seal ring the inner surface of the between the piston 18 and provides a sealing effect a degree that, when a pressure the cylinder 17 to such between the interior and differential has occurred the 17 upon displacement of exterior of the cylinder to cylinder, air is permitted piston 18 relative to said between the seal ring flow into the cylinder through said cylinder 17 to eliminate and the inner wall of the is held but when the piston 18 pressure differential, the interior and exterior stationary, air flow between The inner wall of the of the cylinder 17 is blocked. gases contacted by the combustion piston 18 which will be 17 is coated with a coating collected in the cylinder as the coating film 19. film 19' of the same material 16 is formed of a polytetrafluoro- The gas exhaust passage and a inner diameter of 8 mm ethylene tube having an of consisting of a plurality length of 1.5 m, said tube together by means of couplings sections detachably coupled 16 is provided filter 21. In the gas exhaust passage communi- of a cylindrical casing means 22 which consists passage 16 and packed with cating with said gas exhaust to cause glass wool 23. A driving device 24 is provided

18 within the cylinder 17, displacement of the piston gear 25, a stepless speed change which comprises a motor 28 25 and a guide structure 26 connected with said motor a speed change gear 26 and interconnecting said stepless 18. The guide structure 28 piston rod 27 of the piston support plates 30, 31, an is composed of opposed fixed 29 connected with the stepless externally threaded rod

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53,018 /73 speed change gear 26 and rotatably supported by said

support plates 30, 31, a guide rod 32 extending across

said support plates 30, 31 with the opposite ends secured

thereto respectively, and a movable plate 33 slidably

mounted on said guide rod 32 at one end with said threaded

rod 29 threadably extending therethrough and having the

piston rod 27 connected to the other end thereof. The burning and collection apparatus for

combustion gases, of the construction described above

is operated in the following sequence: Namely, the

combustion chamber 2 is heated by the electric type heat-

ing furnace 3 at first and then the air pump 9 is set in

motion to feed air into the combustion chamber 2, after

opening the sample material supply port 7 of said combus-

tion chamber. The air supplied from the air pump 2 is

dehumidized during passage through the dehumidization

unit 11 by the silica gel 13 disposed in said dehumidi-

zation unit. The dry air leaving the dehumidization unit

11 after passage through the silica gel 13 passes in the

flow meter 14 and enters the combustion chamber 2 from

the gas supply port 4. The flow rate of air from the

air pump 9 is regulated to a desired value, e.g. 100 i/hr. on the flow meter 14. The air .entering the combustion

chamber 2 is heated therein and discharged to the outside

from the sample material supply port 7. The temperature

of the combustion chamber 2 or, more specifically, the

temperatures of the surface of the quartz beads 8 and

the inner wall of the combustion chamber 2 which are

heated most, are measured by means of a thermocouple 34

inserted into the combustion chamber 2 from the sample

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53 018 /73 material supply port 7, to adjust the temperature of

said combustion chamber 2 to a desired value, e.g. 700C.,

by controlling the current being supplied to the electric

heating furnace 3. The stepless speed change gear 26

is previously adjusted such that the quantity of gases

sucked in a unit time will be slightly larger than the

quantity of air supplied in a unit time by the air pump

9, and then the motor 25 is set in motion to operate

the piston 18 for suction stroke. In this case, the

externally threaded rod 29 rotates and the moving plate

33 in threadable engagement with said rod 29 displaces

towards the motor 25 along the rod 29 and the guide rod

28, whereby the piston 18 is pulled for suction stroke.

Simultaneously with starting the suction stroke, a pre-

determined weight of a sample material is placed in the

combustion chamber 2 from the sample material supply port

7 and then said supply port 7 is closed by the cap 6.

The sample material placed in the combustion chamber 2

burns therein generating a variety of combustion gases.

The combustion gases in most cases contain aqueous vapour.

The combustion gases thus generated ascend in the combus-

tion chamber 2 and are collected in the cylinder 17

through the gas exhaust passage 16. The aqueous vapour

entrained in the combustion gases is cooled and condensed

while the combustion gases are passing in the gas exhaust

passage 16 which is considerably long in length, and the

resulting water attaches to the inner wall of the exhaust

passage 16 and to the glass wool in the filter means 21,

in the form of water droplets. The smoke and soot result-

ing front the combustion are removed from the combustion

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53.018 /n combus- during passage of the gases by the filter meanseT them .means, and little of tion gases in said filter condi- A sub-atmospheric pressure reach the cylinder 17. the cylinder 17 and combustion tion tends to occur in since stroke of the piston 18 chamber 2 in the suction unit gases into the gas collection the suction rate of of air from the than the supply rate is slightly larger does however, such condition air pump 9. In practice, 2 17 and combustion chamber not occur and the cylinder normal pressure, because are maintained at substantially through between into the cylinder 17 the external air flows the inner on the piston 18 and the seal ring 20 mounted no case will the 17. Therefore, in wall of the cylinder chamber 2 vary into the combustion rate of air supplied otherwise occurring in due to the pressure reduction condi- and hence the combustion said combustion chamber, gases constant. The combustion tions can be maintained concentrations cylinder 17 at high are collected in the of time, e.g. 1 2 minutes, after the in a short period substantially its movement without piston 18 has ceased they are to the outside, though being allowed to leak gases air. Thus, the combustion diluted slightly with chamber 2 are introduced generating in the combustion distance 17. In this case, the entirely into the cylinder is measured piston 18 for suction of displacement of the In the of the gases collected. to know the total volume however, by the present inventors, experiment conducted so that over a constant distance the piston was pulled might be constant. the gases collected the total volume of remaining in the combustion gases It was confirmed that

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53. 018/73 the. combustion chamber 2 could be collected entirely in the cylinder 17, by pulling the piston 18 further over cm continuously after the completion of combustion of the sample material. Immediately after the combustion gases have been collected in the cylinder 17 in the manner described, the piston rod 27 is removed from the moving plate 33, the section of the gas exhaust passage 16 leading to the cylinder 17 is disconnected from the remaining section at the coupling 21, a cylindrical gas cell for infrared absorption spectrum, having an internal volume of 250 cc, a light path length of 10 cm and a reduced pressure below 0.5 torr is connected to the disconnected end of said section of the gas exhaust passage 16, and the combustion gases in the cylinder 17 are forced into said gas cell with pressure by pushing the piston 18 by hand. In the experiment, the pressure of the combustion gases was returned to the atmospheric pressure just before the measurement. It was also confirmed S that the combustion gases collected in the cylinder 17, are dissipated sufficiently within said cylinder even right after the collection and segregation of gases is not seen anywhere in the cylinder. In order to evaluate the accuracy of the subject apparatus in its combustion gas generation and collection operation, 0.1 g of nylon 66 was burned 6 times each under such combustion conditions that the combustion temperature was 700 0 C, and the supply rate of air was 100 L/hr, and the quantitative analysis of the components of the combus- tion gases in each run was conducted by the infrared absorption spectrum method, with the results shown in the

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53. 0 18/73 Lable provided below:

Run No. CO2 CO NH3 HCN CH4 C2 H4 C2H2

330 181 9 29 62 86 19 1

177 7 28 62 78 16 2 339

305 190 7 30 64 82 3

315 174 10 28 62 84 13 4

167 9 26 60 80 13 338

340 190 12 28 62 84 12 6

328 180 9 28 62 82 14 x

4.1 4.6 19.2 4.4 1.9 2.8 10.0

In the above table, i represents the mean value

and represents the standard deviation percentage. It was found that the quantities of the comp- with the nents other than ammonia can be determined standard deviation within 10 as shown in the above table. poor probably The accuracy in determination of ammonia is in case because ammonia is generated in a small quantity of ammonia of nylon 66 and also because the quantity the generated is influenced even by a slight change in combustion conditions. The accuracy in determination of quantity of acetylene was also somewhat poor because the in combus- acetylene formed is varied by a slight change of air. tion conditions, particularly in the supply rate

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53.018 73 It was confirmed that the quantitative analysis of other plastics can be achieved with the same accuracy as in the case of nylon 66. Since the accuracies depicted above include the error inherent to the determination by the infrared absorption spectrum, it is assumed that the actual accuracies in the formation and collection of combustion gases by the subject apparatus would be better than those shown in the table provided above. The present inventors conducted another ex- periment to determine the proportion in which a water- soluble gas is collected in the cylinder 17 in the gaseous state when such water-soluble gas is generated in the combustion chamber 2. In the experiment, 0.1 g of poly- ethylene which generates a large quantity of water when burned was placed in the combustion chamber 2 and burned therein under the same conditions under which it is normally burned, i.e. at a temperature of 70000C. and with air supplied at the rate of 100 1/hr. In collecting the resulting combustion gases in the cylinder 17, the aqueous vapour present therein was removed therefrom by condensing it in.the gas exhaust passage 16. Concurrently with the completion of combustion, 6.06 cc of ammonia gas was introduced into the combustion chamber from the supply port 4 along with 100 1/hr or air. The ammonia gas was collected in the cylinder 17 through the gas exhaust passage 16. The quantity of ammonia gas collected in the cylinder 17 was 90 of that introduced from the supply port 4. Thus, it will be understo6d that only 10 of the ammonia gas had been dissolved in water before the ammonia gas reached the cylinder 17. It is generally known that

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53.018/73 plastics or other materials which will generate water-

soluble gases when burned, produce less amounts of water

than the aforesaid polyethylene and that plastics generate

all of the water-soluble gases which are to be generated

therefrom, in the initial stage of combustion in which

the quantity of water produced is relatively small. In

view of the above, it is assumed that the proportion of

the water-soluble gas actually collected in the cylinder

17 would be more than 95 The present invention has been described herein

in terms of an embodiment in which the atmospheric air

is introduced into the combustion chamber. It should be

understood, however, that aoordirng to the Inventin

combustion under a variety of conditions can be reproduced

in the apparatus by introducing into the combustion chamber

airs having oxygen concentrations different from that in

the atmospheric air, and other oxygen-containing gases.

It should also be understood that gases resulting from

thermal decomposition can be formed and collected in the

apparatus by introducing inert gases, such as nitrogen

gas, in lieu of air.

As may be understood from the foregoing des-

cription, the para the inventin ie advantageouse -n th-a tho supply rate of air or other gas introduced

into the combustion chamber and the flow rate of the

gases generated in said combustion chamber and being led

to the gas collection unit can be balanced and in-that-

the conditions under which the combustion or thermal

decomposition is carried out can be maintained unchanged from the start to end of the combustion or thermal decom-

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position, without allowing super- or sub-atmospheric

pressure to develop in the combustion chamber. Also the gases gas generated in the combustion chamber can be collected in the collection unit without substantially diluting the, and hence

the analysis of gas composition can be achieved with high

accuracy. It should also be noted that the temperature of the combust- chamber ion chamber and the supply rate of air to said combustion can optionally be adjusted and a variety of combustion condi-

tions can be reproduced. The mode of combustion of an inflammable the state material in the actual fire varies largely depending upon

of fire. For instance, inflammable materials decompose at rel-

atively low temperatures in the initial stage of combustion,

generating gases which constitute'smokes. By using the apparatus

embodying the invention, the gas generating states under of the various conditions can be known by changing the:temperature

combustion chamber. In the case of fire in buildings, air is houses short in most cases, whereas in the case of fire of wooden

air is supplied sufficiently in most cases. With the apparatus

embddying the invention, the combustion under various conditions

can be reproduced by changing the supply rate of air to the

combustion chamber in the light of the foregoing facts. An additional advantage is that, since the gas exhaust

passage is provided between the combustion chamber and cylinder, vapour which has a cooling effect sufficient to condense aqueous

and by which

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53.018/73

water is prevented from being collected in the cylinder,

water-soluble gases can be collected in said cylinder

substantially entirely in the gaseous state even if such

gases are generated in the combustion chamber, and

therefore, the quantitative analysis of the water-

soluble gases can be achieved simply by the same method

as that for the quantitative analysis of other combustion

gases or thermal decomposition gases. It should also be noted that in the apparatus

®ithe inv to the generation and collection of combus-

tion gases and thermal decomposition gases in a variety

of atmospheres are possible by supplying into the

combustion chamber airs having oxygen concentrations

different from that in the atmospheric air or inert gases

such as nitrogen gas, basides the atmospheric air.

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Claims (4)

53. 018/73 THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A burning and collection apparatus for

combustion gases, comprsing combustion means having a

combustion chamber for burning a sample material received

therein and a heating furnace for heating the sample

material in said combustion chamber to a predetermined and

adjustable combustible temperature, gas supply means for

leading-to an inlet of said combustion chamber air or

other gas at a predetermined and adjustable rate,

dehumidizing means for removing moisture from the com-

bustion gases exiting through an outlet of said

combustion chamber .by cooling said combustion gases and

thus condensing an aqueous vapor contained therein, gas

collection means having a cylinder for receiving the

combustion gases from said dehumidizing means and a

piston slidably fitted in said cylinder, said piston being

provided on its outer periphery with seal ring means which

is in light contact with an inner surface of said cylinder

and driving means for displacing said piston at a pre-

determined and adjustable rate in a direction of sucking

the combustion gases into said cylinder.

2. A burning and collection apparatus for

combustion gases according to Claim 1, wherein the

inner peripheral surface of said cylinder and the inner

wall surface of said piston are lined with coating films

of plastic materials little reactive wEth the combustion

gases to be collected in said cylinder.

3. A burning and collection apparatus for

combustion gases, comprising combustion means having a

combustion chamber for placing a sample material

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53,018/73 therein and an electric heating furnace capable of adjustably

heating said combustion chamber, air supply means for

supplying air into the combustion chamber at an adjusted rate piston-cylinder type gas collection means having a cylinder

communicated with the combustion chamber by a gas exhaust

passage having a cooling effect sufficient to condense

aqueous vapour and a piston disposed slidably in said

cylinder, the dimensions of said cylinder and piston being

so selected as to provide between said cylinder and piston

a sealing effect to such a degree that when a pressure

differential has occurred between the interior and exterior

of said cylinder, a gas is allowed to flow into or out from

said cylinder to eliminate the pressure differential whereas the when there is no such pressure differential the flow of

gas into or out from said cylinder is blocked, and driving means for operating said cylinder at an adjusted predetermine at a' speed to suck the combustion gases into said cylinder rate corresponding to the supply rate of air into the

combustion chamber.

4. Burning and collection apparatus for

combustion gas substantially as hereinbefore described with

reference to the accompanying drawings.

DATED THIS 19th DAY OF MAY 1975.

MATSUSHITA ELECTRIC INDUSTRIAL CO. L] By Its Patent Attorneys

CLEMENT HACK CO. Fellows Institute of Patent Attorneys of Australia.

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