Abstract
At Nippon Telegraph and Telephone Corporation, environmental investigation of machine rooms was carried out using a handy and cheap metal plate exposure method from the viewpoint of preventive maintenance on communication equipment.
It was proven that this method is effective for evaluating indoor environments. However, when the exposure period of the metal plate is shortened, the business trip for the installation of the metal plate increases, and the low cost advantage is lost.
We examined a handy and cheap method which was able to evaluate atmospheric environment during a short-term exposure.
The main results are shown as follows.
(1) We found the condition of non-sealing up structure to maintain corrosion amount information on a metal plate for long term.
(2) We created a device that continuously records the amount of corrosion using a non-sealing up structure. We named “Environmental corrosion recorder”. Six pairs of metal plates are installed in the recorder. By using this recorder, the business trip operation of conventional method is decreased to 1/4 or less.
(3) We carried out experiments on this recording method and the conventional metal plate exposure method concurrently over four months in six places. It was proven that the data taken from the recorder was almost the same as that taken using the conventional method.
(4) The correlation coefficients for the amount of the sulfur corrosion detected by the two evaluation methods were 0.96, 0.96 and 0.76 in the machine room, the office and outdoor, respectively. The correlation coefficients for the amount of the chlorine corrosion detected by the two evaluation methods were 0.93, 0.97 and 0.96 in the machine room, the office and outdoor, respectively.
