会社のニュース Technical Comparison: Pilot-Operated vs. Direct-Operated Gas Regulators

Technical Comparison: Pilot-Operated vs. Direct-Operated Gas Regulators

Choosing the right gas regulator for an application requires an understanding of the fundamental differences between direct-operated and pilot-operated designs. Fisher gas regulators are manufactured in both styles to provide solutions for a wide range of industrial and commercial needs. A direct-operated regulator uses the downstream pressure directly against a diaphragm to move the valve plug. This design is simple, robust, and features very few moving parts. It is generally the best choice for residential service, small commercial buildings, and applications where the flow rate is relatively constant and the required accuracy is within a moderate range.

In contrast, a pilot-operated Fisher gas regulator uses a secondary, smaller regulator (the pilot) to amplify the pressure signal and control the main valve. This "two-stage" approach allows the regulator to maintain extremely tight pressure control over a wide range of inlet pressures and flow rates. Pilot-operated regulators are the preferred choice for high-capacity applications such as city gate stations and large industrial factories. They offer much higher accuracy and are capable of handling much larger volumes of gas than a direct-operated valve of the same size. However, they are more complex and require a cleaner gas stream to ensure that the small orifices in the pilot do not become clogged.

[Image comparing direct-operated and pilot-operated regulator internal mechanisms]

The concept of "droop" is a critical factor when comparing these two types of regulators. Droop is the reduction in outlet pressure that occurs as the flow rate through the regulator increases. Direct-operated regulators typically exhibit more droop because the spring must extend further as the valve opens, which reduces the force it exerts. Pilot-operated regulators, however, are designed to compensate for this, resulting in a much flatter pressure curve. For applications like gas turbine fuel lines, where a constant pressure is mandatory for operational stability, the superior accuracy of a pilot-operated Fisher regulator is worth the additional complexity and investment.

Maintenance requirements also differ significantly between the two designs. Because direct-operated regulators are simpler, they are generally easier to maintain and can handle "dirty" gas with higher concentrations of particulates or liquids. Pilot-operated regulators are more sensitive to contaminants, making the installation of upstream filters and scrubbers a necessity. As a manufacturer, we provide detailed maintenance manuals and training for both styles of regulators. We recommend that users evaluate their specific gas quality and maintenance capabilities before deciding which technology to implement. Our engineering team can provide a detailed analysis of your system parameters to help you make an informed decision.

Regardless of which type you choose, purchasing a Fisher gas regulator ensures that you are getting a product built on decades of research and development. We utilize advanced computational fluid dynamics (CFD) to optimize the flow paths in both our direct and pilot-operated models. This ensures maximum flow capacity and minimum pressure loss, improving the overall efficiency of your gas system. By offering a complete portfolio of regulation technologies, we empower our customers to build systems that are perfectly balanced for their specific technical and budgetary requirements. Trust our manufacturing excellence to provide the precision and reliability your gas infrastructure deserves.