A SYSTEM FOR CIRCULATING AIR IN A GAS CHROMATOGRAPH OVEN

Abstract: A system for circulating air in a gas chromatograph oven, in which warming and cooling is regulated with the help of a heat resistor (9), a sensor (14), and one and only one shutter (8).

Description: A system for circulating air in a gas chromatograph oven This invention relates to a system for circulating air in a gas chromatograph oven, in which the circulation system as interpreted in this context refers to recirculation inside the oven as well as to both partial and complete exchange of air from outside of the oven. Hitherto known air circulation systems consist of, for example, opening the oven cover and allowing air to flow out and, at the same time, ambient air to flow into and through the oven, when it is cooled, and when the oven is warmed up, air is recirculated inside the oven using dif- ferent recirculation methods. Such air circulation systems are also known which take air from outside of the oven and circulate it through the oven and remove it from the oven using another separate channel. However, a drawback of the mentioned solutions is the more or less uncontrollable cir- culation; the air is not directed to flow so that its effect would be the best possible. Another drawback is the com¬ plexity of the apparatus used in those cases where the air is taken from outside of the oven. The object of this invention is to avoid the troublesome drawbacks in the art and achieve an effective, controllable, and at the same time simple and economical system for recir¬ culating air in a gas chromatograph oven. In the system of the present invention the circulation of air is arranged to occur either completely inside of the oven or either partially or completely to outside of the oven by regulating the circulation with one and only one shutter so that the shutter either closes the inlet and outlet channels completely so that the internal circulation channel is com¬ pletely open or the shutter opens the inlet and cutlet channels partially or completely so that the internal cir - culation system is correspondingly partially resp. com¬ pletely closed. The invention is described more specifically in the follow- ing text by referring to the attached figure. The numbers in the figure refer to the following parts: number 1 refers to the column which is located in an oven that is surrounded by an insulation that is designated by the number 10. Number 2 refers to the fan which puts the ' air into motion and number 3 the motor that turns the fan. Number 4 indicates a guide plate which is advantageously attached to the column frame, number 5 refers to the internal circulation channel which contains a heat resistor 9, and numbers 6 and 7 in¬ dicate the outlet resp, inlet channels. Numbers 11, 12 and 13 indicate guide walls and net that play an important part in directing the air and smoothing its flow. Further essen¬ tial parts of the system are the sensor, for example a thermo¬ element, which is indicated by the number 14- and is used to regulate the oven temperature, as well as the shutter 8, which is the core ,of the air circulation's regulation. The system functions as follows: When the oven temperature needs to be raised, shutter 8 is placed into position A, at which time the fan ' 2, for example a rotary fan, circulates air through channel 5 past the resistor 9, so that the air warms up while passing over the functioning resistor 9. The flow is directed with the help of a perforated plate 11 and smoothed with the help of a net 12, as well as directed to flow along the wound column and not through its center, with the help of guide plates 4 which are located at the ends of the wound column 1. The sensor 14 measures the temperature and adjusts the heating power to achieve the desired tempera¬ ture. If it is desired to mix some cooler air from outside of the oven into the circulation, shutter 8 is opened to, for example, position B, whereby a portion of the air is removed through channel 6 and a corresponding amount of air from outside of the oven comes into the air circulation inside the oven through channel 7. If the oven needs to be ventilated thoroughly as is usual at the end of the runs, the shutter is turned to position C, whereby all of the circulating air comes from outside of the oven. If necessary, shutter 8 can be even manually turned without steps, but automatic control is also very easily arranged, for example with an electric motor. In such a case where the oven tempe¬ rature needs to be below room temperature, an appropriate cooling agent can be fed through channel 7. The complete regulation of the air circulation as mentioned above can thus be accomplished with the help of one and only one shutter 8. Warming and cooling form an entirety whose essential parts are the shutter 8, the resistor 9, and the sensor 14. The functioning of the mentioned parts can easi¬ ly be altered to occur completely automatically. _OMPI

Claims: What is claimed is: 1. A system for circulating air in a gas chromatograph oven that has a fan (2) to put the air into motion, a heat resis¬ tor (9) to warm up the air, and a sensor (14) to control the air temperature, and in which air can be taken from outside of the oven and accordingly returned to the outside; c h a ¬ r a c t e r i z e d i n that the circulation of air is arranged to occur either completely inside of the oven or either partially or completely to outside of the oven by regulating the circulation with one and only one shutter (8) so that the shutter (8) either closes the inlet and outlet channels (6,7) completely so that the internal circulation channel. (5) is completely open or the shutter (8) opens the inlet and outlet channels (6,7) partially or completely so that the internal circulation system (5) is correspondingly partially resp. completely closed. 2. A system according to patent claim 1, c h a r a c t e ¬ r i z e d i n that the heat resistor . (9) is located in the internal circulation channel (5) . 3. A system according to patent claim 1, c h a r a c t e ¬ r i z e d i n that the shutter (8) can be opened/closed without steps. 4. A system according to patent claim 1, c h a r a c t e ¬ r i z e d i n that walls (13) , perforated plate (11) , guide plates (14) , and net (12) for smoothing the flow are used to accomplish an appropriate air flow. 5. A system according to patent claim 1, c h a r a c t e ¬ r i z e d i n that the outlet channel (6) and the inlet channel (7) are located side by side. "^URt f OMPI

Inventors: KUMLIN KLAUS, NORONEN AATTO, SARESKIVI HENRIK
Applicants: KUMLIN KLAUS, NORONEN AATTO, ORION YHTYMAE OY, SARESKIVI HENRIK
Application year: 1981
Main classification: B01D15
IPC codes: B01D15, G01N30