Overview of 55225 Spirax Sarco Regulator
The Spirax Sarco 55225 is part of Spirax’s 25P pilot-operated pressure reducing main valve family. This 1-¼” NPT, cast iron regulator is designed for steam pressure reduction, offering precise control, dead-end shutoff, and reliable performance in commercial and industrial steam systems.
It uses downstream sensing feedback through a pilot to adjust the main valve opening to maintain the desired set pressure. The 55225 model can handle steam pressures up to 250 psi and temperatures up to 450 °F.
Features
Pilot-operated main valve for accurate steam pressure regulation
Self-acting diaphragm mechanism with external feedback sensing
Dead-end shutoff capability meeting ANSI/FCI 70-2 Class IV standards
Cast iron body construction with stainless steel trim
Uses color-coded pilot springs for ease of setpoint selection
Interchangeable spring modules for various pressure ranges
Horizontal installation recommended for best performance
Wash-through design to reduce debris retention
Designed for steam service with proven durability
Specifications
| Specification | Details |
|---|---|
| Model / Series | 55225 (25P Series) |
| Nominal Size | 1-¼” NPT |
| Body Material | Cast Iron |
| Maximum Pressure (Steam) | 250 psi |
| Maximum Temperature | 450 °F |
| End Connections | FNPT (female NPT) |
| Shutoff Rating | ANSI/FCI 70-2 Class IV dead-end shutoff |
| Control Type | Pilot-operated with feedback sensing |
| Sensing Line | External downstream sensing |
| Internal Trim | Stainless steel (valve seat and disc) |
| Mounting Orientation | Horizontal recommended |
| Spring Range Options | Multiple color-coded ranges (e.g. 3-30 psi, 20-100 psi, 80-250 psi) |
| Service Media | Saturated steam |
| Typical Applications | Main steam pressure reduction, protecting downstream equipment, boiler control systems |
Applications
The 55225 Spirax Sarco regulator is suited for a wide range of steam pressure control applications, including:
Main steam line pressure reduction
Feedwater pump steam control
Steam to conform to process equipment inlet pressure requirements
Steam regulation for heat exchangers or control valves
Industrial boiler downstream protection
Its pilot-operated design enables stable regulation even under varying load conditions.
Benefits
Precise pressure regulation with stable control dynamics
Strong shutoff performance to prevent overpressure
Modular pilot spring system for easy reconfiguration
Built for durability in steam service conditions
Support for a broad operating range (pressure and temperature)
Maintenance and service ease with standard internal parts




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