Pressure balanced plug valves are used where pulsating or static high pressures are present. The benefi t a dynamic pressure balanced inverted plug gives is that it ensures equalised pressure between the plug and upper and lower body chambers.
Pressure is balanced by two holes in the plug which connects the plug port with the lower and upper cavities.The hole in the upper end is provided with a check valve so the pressure is always equal to the large end cavity and it is always equal to or greater than the line pressure in the small end cavity.