Fundamental Principles of Pilot Operated Regulators Class 193

摘要

The self-operated regulators are limited in application as to the level of outlet pressure that can be controlled. In addition, diaphragm effects and spring effects still exist in most designs. To obtain better regulation, it is oftne necessary to use gas-loading systems. The simplest type of gas-loading system is the constant loading pressure system illustrated in Figure No.23, Without gas loading, this regulator would control a very low outlet pressure due to the lightweight of its parts. However, when gas pressure is imposed over the diaphragm, the outlet pressure increases the same amount as the gas-loading pressure. The samll pilot regulator is set for a given pressure and the needle valve is opened slightly to cause a constant bleed. Since the small pilot regulator is operated at a constant flow rate, its pressure does not change and this pressure is imposed on the diaphragm of the main regulator.