벨로즈 튜브를 이용한 수도계량기 동파방지 설계 및 유한요소해석

Abstract

A water meter is widely using to measure the amount of water flow. Most cases of the water inside of a water meter are exposed to a change of phase at a temperature below a freezing point in winter. This phase transition causes the serious malfunction such as shutdown of a process and breakage of a water meter because of volume expansion of inside matters. In this paper, a new design structure of a water meter, which had a bellows tube, is proposed for preventing the breakage by freezing. Then breakage prevention effect was verified using finite element analysis. As the results of FEA on new design water meter, maximum magnitude of Von-Mises stress is 75.58MPa at working pressure of 0.3MPa and it belongs to a safe limit compared by a yield stress of a brass material. Also, bellows tube has extra volume about 90% and over compared with increased volume generating ice so it prevents pressure increase generated by lack of volume inside of water meter. Through comparison with FEA results of optimized bellows tube and design standard of bellows tube by EJMA, dimensional stability of a bellows tube was evaluated and it confirmed that shape dimension of optimized bellows tube is safety. Therefore, it is confirmed that the new water meter can afford to apply a bellows tube in order to effectively prevent the breakage.