Determination of Flow Rate Characteristics of Pneumatic Solenoid Valves Using an Isothermal Chamber

Abstract

In this paper, two new methods for obtaining the sonic conductance and the critical pressure ratio of pneumatic valves are proposed. Both methods use a chamber that can approximate isothermal conditions. This was achieved by filling the chamber with metal wire, which creates a larger heat transfer area and heat transfer coefficient. The sonic conductance and the critical pressure ratio are obtained by measuring the pressure in the chamber during charging and discharging. These methods take only seconds to perform and require less energy than the ISO 6358 procedure. The major factor in the error for the pressure response during the charging of the isothermal chamber is the upstream pressure change. Nevertheless, the sonic conductance can be determined within a 3% uncertainty. In addition, the sonic conductance calculated from the pressure response during the discharging of the chamber can be determined within a 1.2% uncertainty.

A new method for calculating the sonic conductance of airflow through a short-tube orifice

“…Three different methods have been presented for measuring the flow-rate characteristics of pneumatic components: 8,[18][19][20] the discharge method, the in-line method and the isothermal discharge method. The discharge test method is air-and time-saving, but the tank volume must be changed as a discharge time of 10-15 s is required.…”

Stability Analysis of Pneumatic Cabin Pressure Regulating System with Complex Nonlinear Characteristics

“…where 1 is the effective area of pressure applied on diaphragms, 10 is the preload spring force on diaphragms, calculation formula equation (3) in [6] and equation (1) in [7], 1 is dynamic solution of the following equation:…”

Determination of flow rate characteristics for pneumatic valves

“…mrT pv m (3) Equation (3) is used together with equations (1) and (2). Equations (4) and (5) can be obtained from these and they express a derivative of pressure continuance p 2 in the tank.…”

“…Values of critical pressure ratio b for each final pressure in the tank were determined based on knowledge that the linear part of the curvature of the charge is describe by equation (1) and the behaviors of flow rate in the second part of the curvature is described by equation (2). Of note is that the critical pressure ratio b expresses the divide of the downstream and the upstream pressure which flow becomes choked [1].…”