Shinku

Sources of the irreproducibility in measuring pressure by means of the BET adsorption apparatus with the zero-manometer are described. These have been examined experimentally and found to be caused by the contamination in the zero-manometer (ΔP_e), the vibration of mercury in the manometer (ΔP_v) and the differences in shape of mercury meniscus between the right and left tubes of the manometer (ΔP_m). In this paper, the new method of indirectly determining these systematic errors of pressure is proposed. The maximum values of the above errors, (ΔP_e) max, (ΔP_v) max and (ΔP_m) max were (4.7±0.5) Torr, ±0.7 Torr and ±0.2 Torr, respectively. In order to examine the effects of the above systematic errors on the surface area S, the simulation on the processes of S-measurement has been carried out using the computer, NEAC 3200 model 50 system. According to the results of simulation, the values of S for the samples, which were below 100 m², were found to be scattered with the error of several tens per cent. On the basis of these results, the surface area S can be measured with the accuracy of ±1%, and the technique of S-measurement can be mastered for about 10 days.

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To improve production leak testing of components of air conditioner, automobile, etc., new automatic systems with helium mass spectrometer leak detector were developed. Design basis and performances of typical two systems for automatic leak testing based on hood method and reverse hood method are described. In addition, reliability and durability of vacuum components for high speed operation of the system and the clean-up time of helium leak detector are discussed. A full automated leak testing system makes possible by adding sub-systems such as devices of loading, unloading, selecting good or leaky components, to the automated reverse hood method's system. Summarized performances of two systems are as follows :
A) Automatic hood method's leak testing system.
1. Detectable leak rate in working condition :
About 1×10^-6 Torr l/sec if the work volume is about 1 liter.
About 2×10^-6 Torr l/sec if the work volume is about 2 liter.
2. Detectable sensitivity including all system :
About 6×10^-9 Torr l/sec/div. if the work volume is about 1 liter.
About 1.3×10^-8 Torr l/sec/div. if the work volume is about 2 liter.
3. Operation speed : 2530 seconds per each one.
4. Helium comsumption : 7m³ monthly, 7hr operation/day, 22 working days/month.
B) Automatic reverse hood method's leak testing system.
1. Detectable leak rate in working condition :
About 1×10^-6 Torr l/sec if the chamber volume is about 100 liter and the operating speed is 20 seconds per each one.
2. Detectable sensitivity including all system :
About 8.5×10^-9 Torr l/sec/div. if the chamber volume is about 100 liter and the operating speed is 20 seconds per each one.

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