National Institute of Occupational Safety and Health, Japan
Research on Elimination of Static Charges by the Use ob Radioisotopes (4st Report) — Elimination of Static Charges in Oil —
RR-15-1
K.Sakanushi R.Tanaka S.Kouzuki T.Kodama Y.Tabata
Our previous work1), has indicated that it is likely to be possible to eliminate the static electricity in various charged materials. Un this paper the writers describe that there is a possibility of charge eliminating in "kerosene" by β-ray.
β-ray source, 90Sr—90Y with a intensity of nominal 20 millicuries is used in this experiment and the test oil is charged with static electricity by a device shown in Fig.1.
Although experimental data were varied according to a day of the work, those data show qualitatively that, an essential problem of eliminating mechanism depends largely upon the intensity of the radioactive source and does not upon the initial chage given in the oil. It was found also that the sliminating efficiency with charged oil is nearly equal to that reported with the charged powder.
Following the results, the writers, as the next step, will further study essential conditions hor eliminating static electricity in a simple charged system constructed with the knouwledge of experimental data so far obtained for vinyl sheet, powder ond oil. Experiments are now under way to delelop a practical eliminator using a radioisotopes.
Study of the Safe Gaps with Hydrogen/Air mixtures
RR-15-2
H.Tsurumi T.Matsuda
Experimental Safe Gaps with Hydrogen/Air Mixtures have been mesured by 8 liter spherical stainless steel vesselwith 1 inch flanges at atmospheric pressure and 0.5kg/cm2 gauge pressure.
From the experiments, the following facts became evident.
Maximum Experimental Safe Gap(m. e. s. g.) is 0.22mm at atmospheric pressure.
Experimental Safe Gap is influenced by concentration and pressure.
Hydrogen concentration from 18 percent to 51 percent belongs to Explosion Grade No.3.
Experimental Safe Gap is correlative ti quenching distance.
Study of the Flash Temperatures
RR-15-3
S.Yagyu
The limiting temperature condition to prevent gaseous explosions caused on the flammable vapors has been investigated. The apparatus was set up to mesure the flash temperatures(i. e. the lower flash points and the upper flash points) of 27 flammable liquids in air and 14 ones in oxygen. These data obtained in the experiments have been used to calsulated the flammable limits of those flammable vapores in air and oxgen, and then the method to predict the exsiting range of flash temperatures has been established.
