Combined use of a simplified nitrogen generator and an oxygen absorber for efficient medium-scale low oxygen treatments for the eradication of museum pest insects [Original title and text in Japanese]

In Japan, oxygen absorbers such as RP-system K-type are commonly used for the eradication of insect pests from small museum objects (up to approximately 1001 by volume). However, in case of medium scale treatment (commonly up to about 1 cubic meter by volume), much oxygen absorber will be needed and it is not cost-effective. In this situation, combined use of nitrogen and oxygen absorber is a recommended strategy. For larger volumes we introduced a chamber (approximately 3 cubic meter) attached to a high efficiency nitrogen generator with a humidity adjusting device. But this system is expensive, and it is not generall easy for museums to purchase this kind of system. Therefore, we aimed to use a more cost-effective, small scale and easy to operate nitrogen generator system to facilitate medium scale low oxygen treatment, which is now in high demand in most museums. Examples of such nitrogen generators are Veloxy system, product of Italy, and testing machines are being considered by some companies in Japan. We used a nitrogen generator from Koflok Co. Ltd. Japan for our experiments. It can generate approximately 3001/hour of 99.9 percent nitrogen. The generator is 58 Kg in weight, 410 mm in width, 410 mm in depth and 715 mm in height. Humdification of nitrogen is performed by a special membrane system which enables incorporation of water vapour from the surrouding air. We tested the efficacy of the sysmte using air tight clear plastic bags (ESCAL) of which inner volume is up to 1 cubic meter. With about three cycles of pulling out of air inside and flusing humidified nitrogen, the oxygen concentration inside the bags could be reduced to approximately 1 percent. By inserting an appropriate amount of oxygen absorbers inside the bags at the start of the pulling out - flushing cycles, low oxygen treatments were easily performed for actual infested objects.