Yokohama Waterworks Commemoration Hall / Various tangentiai-flow-impeller water meters2
Yokohama was the first city in Japan in which a modern waterworks system was constructed. The Yokohama Waterworks Commemoration Hall and Waterworks Technology Commemoration Hall displays materials and videos that present how Yokohama's waterworks system was developed. (For more information, see the February 2010 issue of the PR magazine pla-topia.) http://www.city.yokohama.lg.jp/suidou/kyoku/torikumi/suidou-pr/kinenkan/
The single-case water meter has an external case that serves as a nozzle to accurately rotate an impeller. The external case contains only an impeller. The multiple-case water meter has a plastic case inside a metallic external case. The plastic case contains an impeller. These cases ensure accurate integration even when only small volumes of water are consumed. Water meters are subject to certification by the government (every eight years). The water flow wears metallic parts down after long periods of service. This adversely affects the metering performance of single-case water meters. Multiple-case water meters, on the other hand, can serve for many years simply by replacing the external case. The external case serves merely as a container, while the internal case performs the nozzle function.
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Types of water meters | |
Plastic parts making up a tangential-flow-impeller water meter |
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Current tangential-flow-impeller type | |
Auxiliary stop cock |