Anti static structure: when operating the valve, the friction between the ball and the valve seat will produce electrostatic charges and accumulate on the ball. In order to prevent electrostatic sparks, an electrostatic device is specially set on the valve to export the charges accumulated on the ball

Using a multimeter to measure the electrode contact resistance when full of liquid is a convenient method to judge the condition of the pipe wall, although it is only to determine the general value. For accurate measurement, AC bridge must be used, such as "Kohlraush bridge".