Temperature and pressure regulators can be classified into two categories: direct-operated and pilot-operated. The differences between these two types of valves come from their design characteristics. In this article, we’ll break down some of the main differences between the two types of regulating valves and offer some insight into why one type may have advantages over the other in certain applications.
Direct-Operated Regulating Valves
Direct-operated regulating valves are typically more simplistic in both design and operation. These regulators respond directly to variations in downstream pressure, providing the optimized flow and pressure for the system set point. The downstream pressure in the system will work against the balance force provided by the spring, determining the plug position. This means that when using a direct-operated regulating valve, the downstream pressure acts as the loading force. When this pressure increases, the spring in the regulator will be compressed, causing the plug to move toward the closed position and restrict the fluid flow. When the pressure decreases, the regulator spring will decompress, causing the plug to move toward the open position and allow more fluid to pass through. Because the downstream pressure acts as the loading force, direct-operated regulators respond immediately to any change in pressure.
Pilot-Operated Regulating Valves
Pilot-operated regulating valves, while consisting of the same essential components as direct-operated regulators, can be a little more complex because they have a pilot that separates the downstream pressure from the loading force. This pilot allows the loading force to be controlled in relation to changes in pressure. This type of regulating valve is more complex because it also requires an external sense line connected to the downstream piping. This external sense line allows pressure to be measured further downstream, giving more accurate sensing of the true outlet pressure conditions. Pilot-operated regulating valves provide additional control, improving sensitivity and accuracy.
If you have any questions about troubleshooting or maintaining regulating valves in your specific application, please don’t hesitate to contact our team at Sentrol Life Sciences! We represent industry leading manufacturers of sensor and fluid control products for the biopharma, pharmaceutical, healthcare and research & development markets of the Eastern United States. Contact us today for system analysis, troubleshooting, or on-site system service! Give us a call at (888) 877-1778 or fill out the contact form on our website, and a member of our team will get back to you as soon as possible!