Pilot-Operated Pressure Regulators: How They Work and When to Use Them
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What is a Pilot-Operated Pressure Regulator?
A pilot-operated pressure regulator is designed for precise, stable control of downstream pressure — especially in applications with fluctuating loads or higher capacity requirements. In the Spirax Sarco 25P, the downstream pressure is sensed through an external line and communicated to the pilot valve. The pilot then modulates the opening of the main valve to maintain the desired outlet pressure.
Why Choose a Pilot-Operated Design?
Compared to direct-acting regulators, pilot-operated models like the 25P offer:
- Greater accuracy in maintaining set pressure
- Higher flow capacity for a given size
- Tighter shut-off when steam is not required (ANSI/FCI 70-2 Class IV)
These features make them ideal for systems that experience varying steam demand or require consistent output across a wide range of operating conditions.
Common Applications
- Steam pressure reduction for process equipment such as heat exchangers, autoclaves, and kettles
- Stable pressure control in commercial and institutional HVAC systems
- Protection of downstream piping and equipment from over-pressurization
Sizing and Selection Tips
For best performance:
- Match the valve size to system demand using manufacturer Cv capacity charts
- Select the correct pilot spring for your pressure range:
- Yellow: 3–30 psi
- Blue: 20–100 psi
- Red: 80–250 psi (up to 240 psi for 6" models)
- Choose the right construction — cast steel is recommended for pressures above 250 psig or higher temperature service
Seasonal Planning Tip
As cooler weather approaches, steam systems see increased demand. Early fall is the ideal time to confirm your pressure regulators are operating correctly — replacing or upgrading now avoids mid-season downtime and keeps energy efficiency high. If you’re unsure which pilot-operated regulator is right for your system, contact our team and we’ll walk you through the options.