抄録
1) Fire Ratings of Safes and Insulated Containers in U. S. A.
Underwriters’ Laboratory in U. S. A., which has been engaging in fire tests for long, has established fire ratings of safes and insulated containers. They are given in Table 1. The fire test consists of three tests :
(a) Fire resistance test ; a heating of a standardized fire, and allowable interior temperature during the test is 350°F.
(b) Explosion test ; a sudden heating of 2,000°F
(c) Impact test ; an impact from 30ft after being heated and reheating in the inverted position after the impact.
2) Actual Result of Labeled Safes.
Actual results of safes which have been in a fire are given in Tables 2 and 3. According to the Table 3, 88% of labeled safes retained usability of papers, but only 60% of uninspected safes did.
3) Fire Tests of Safes in our Institute. We made fire tests of more than ten safes. Thermal insulating materials of these safes were mainly made of foam concrete, but No. 8 was of rockwool, and No. 15 and No. 16 of gypsum. No. 12 was reheated three days after the fire test, and next day a wet towel was put in it and heated again.
Desirable factor of an insulating material of safe is that the material has not small thermal conductivity but large heat capacity. Foam concrete is suitable for the insulating material of safe because of its much water content.
It was obvious that the insulating material of a safe varied in thickness ; door was very thin, but too thick in both walls.
It is necessary to take out papers from safe as soon as possible after it is involved in fire.
