A volume measurement method for pneumatic pressure vessels using compressed-air discharge

Abstract

Abstract In pneumatic systems, the volume of a pressure vessel can be assumed to be analogous to pneumatic capacitance, and is an important parameter that governs the pressure response of the system. Therefore, an accurate and high-fidelity volume measurement is an indispensable requirement for a high-precision pressure response system. However, in measurement of the volume of pneumatic pressure vessels, the conventional drainage method is inefficient, and may cause damage to the surfaces of the vessel. This paper proposes a new method that uses compressed-air discharge for volume measurement of pneumatic pressure vessels. The primary measurement equipment merely comprises an orifice and a pressure sensor. A formula that calculates the measured volume is obtained based on curves demonstrating the change in pressure derived as part of the experimental analysis conducted in this study. To demonstrate the effectiveness of the proposed method, volumes of three test tanks, considered as pneumatic pressure vessels, were measured using this method. The measurement exercise was performed using three orifices, the effective areas of which were measured in advance. Through use of the proposed method, the error in volume measurement is found to be maintained below approximately 4% by selecting an appropriate shut pressure and orifice diameter. Additionally, the method offers other advantages of being convenient to use, fast, and low cost, as well as non-damaging and non-corrosive to the pressure vessel.