PN16
Product Overview
Spirax Sarco 25P Series self-acting pilot operated pressure reducing valve, sizes ½" to 5", is specifically designed for steam systems. The product senses downstream pressure in real-time through an external pressure sensing line, automatically adjusting main valve opening to ensure downstream pressure remains stable within the set range. The main valve features a single-seat design with stellite-faced plug, providing excellent sealing and durability. The valve body is available in ductile iron or cast steel, with the pilot valve bolted directly to the main valve for compact structure and easy installation. Under no-load downstream conditions, the valve can close completely, preventing media waste and system pressure fluctuations. It effectively reduces high-pressure steam to the required working pressure for equipment, protecting equipment from high-pressure damage.
Technical Specifications
Pressure and Temperature Limits
| Material Type | Flange Standard | Max Operating Pressure (bar g) | Max Operating Temperature (℃) |
|---|---|---|---|
| Ductile Iron (A-B-C-D) | PN16 | 16 | 232 |
| Ductile Iron (A-H-I-J) | PN25 | 25 | 270 |
| Cast Steel (E-F-G) | PN40 | 40 | 270 |
Downstream Pressure Ranges (By Spring Color)
| Spring Color | Pressure Range (bar g) |
|---|---|
| Yellow | 0.2 - 2.1 |
| Blue | 1.4 - 7.0 |
| Red | 5.6 - 14.0 |
Sizes and Connection Types
| Size Range | Connection Type | Applicable Flange Standards |
|---|---|---|
| ½" - 2" | Threaded BSPT(BS21), Flanged | PN16, PN25 (Ductile Iron) |
| ½" - 4" | Flanged | PN16, PN25 (Ductile Iron), PN40 (Cast Steel) |
| 5" | Flanged | PN16, PN25 (Ductile Iron) |
Cv Values (Valve Fully Open)
| Size | ½" | ¾" | 1" | 1¼" | 1½" | 2" | 2½" | 3" | 4" | 5" |
|---|---|---|---|---|---|---|---|---|---|---|
| Cv Value | 3.48 | 6.5 | 10.5 | 14 | 20 | 35 | 56 | 74 | 115 | 123 |
Note
Conversion formula: Cv(US) = Kv × 1.156
Dimensions and Weight
Basic Dimensions (Unit: mm)
| Size | A | B | C | D | E |
|---|---|---|---|---|---|
| ½" | 140 | 193 | 309 | 157 | 466 |
| ¾" | 140 | 193 | 309 | 157 | 466 |
| 1" | 152 | 219 | 308 | 171 | 479 |
| 1¼" | 184 | 219 | 322 | 179 | 501 |
| 1½" | 184 | 219 | 322 | 179 | 501 |
| 2" | 216 | 269 | 338 | 208 | 546 |
| 2½" | - | 346 | 297 | 354 | 651 |
| 3" | - | 346 | 294 | 367 | 661 |
| 4" | - | 397 | 325 | 410 | 735 |
| 5" | - | 397 | 325 | 410 | 735 |
A1 Dimension (Unit: mm) - By Material/Flange Standard
| Size | Ductile Iron BSP JIS/KS10 | Ductile Iron PN16 | Ductile Iron PN25/PN40 | Cast Steel |
|---|---|---|---|---|
| ½" | - | 160 | 160 | 150 |
| ¾" | - | 160 | 160 | 154 |
| 1" | - | 166 | 166 | 160 |
| 1¼" | - | 205 | 205 | - |
| 1½" | - | 216 | 216 | 200 |
| 2" | - | 240 | 240 | 230 |
| 2½" | 286 | 284 | 288 | 292 |
| 3" | 308 | 308 | 316 | 317 |
| 4" | 354 | 353 | 361 | 368 |
| 5" | - | 400 | 400 | - |
Weight (Unit: kg)
| Size | Threaded | Flanged |
|---|---|---|
| ½" | 10.8 | 11.4 |
| ¾" | 10.2 | 12.2 |
| 1" | 13.6 | 16.0 |
| 1¼" | 16.0 | 18.8 |
| 1½" | 15.8 | 20.4 |
| 2" | 26.0 | 31.2 |
| 2½" | - | 62.4 |
| 3" | - | 74.6 |
| 4" | - | 112.2 |
| 5" | - | 132.0 |
Material Specifications
Main Component Materials
| No. | Component | Material | Standard/Grade |
|---|---|---|---|
| 1 | Body | Ductile Iron | QT400-18 |
| 2 | Cover | Ductile Iron | QT400-18 |
| 3 | Cover Bolt | Steel | SAE J 429 Grs |
| 4 | Main Plug | Stainless Steel | AISI 420 |
| 5 | Main Seat | Stainless Steel (½"-2") | AISI 420 |
| 5 | Main Seat | Stainless Steel (2½"-5") | AISI 304 |
| 6 | Main Seat Gasket | Copper | - |
| 7 | Valve Return Spring | Stainless Steel | AISI 302 |
| 8 | Stem | Stainless Steel | AISI 304 |
| 9 | Strainer | Stainless Steel | AISI 304 |
| 10 | Stem Sleeve | Stainless Steel (2½"-5") | AISI 420 |
| 10 | Stem Sleeve | Brass (½"-2") | ASTM B 283 |
| 11 | Spring Guide | Steel (2½"-5") | - |
| 12 | Nut | Steel | SAE J 995 |
| 13 | Cover Gasket | Non-asbestos | - |
| 14 | Pressure Balance Tube | Stainless Steel | AISI 304 |
| 15 | Diaphragm Top Cover | Ductile Iron | QT400-18 |
| 16 | Stem Bushing | Stainless Steel | AISI 304 |
| 17 | Diaphragm Disc Pushrod | Stainless Steel | AISI 304 |
| 18 | Pushrod Guide | Stainless Steel (2½"-5") | AISI 304 |
| 18 | Pushrod Guide | Brass (½"-2") | - |
| 19 | Nut | Steel (2½"-5") | SAE J 995 |
| 20 | Diaphragm Bottom Cover | Ductile Iron | QT400-18 |
| 21 | Diaphragm Disc | Brass (½"-2") | ASTM B 283 |
| 21 | Diaphragm Disc | Ductile Iron (2½"-5") | QT400-18 |
| 22 | Main Diaphragm (2 ply) | Phosphor Bronze (½"-3") | - |
| 22 | Main Diaphragm (2 ply) | Stainless Steel (4"-5") | - |
| 23 | Sleeve | Stainless Steel | 12L14 |
| 24 | Nipple and Orifice | Stainless Steel | AISI 304 |
| 25 | External Tubing Assembly | Stainless Steel | ASTM B 280 |
| 26 | Plug | Steel | SAE 12 L 14 |
| 27 | Connection Bolt | Stainless Steel | AISI 304 |
| 28 | Gasket | Copper (½"-2") | Non-asbestos |
| 28 | Gasket | Graphite (2½"-5") | - |
| 43 | Adjusting Screw | Steel | - |
| 44 | Lock Nut | Brass | - |
| 45 | Pilot Spring | Steel | SAE 1060 |
| 46 | Diaphragm Top Cover | Ductile Iron | QT400-18 |
| 47 | Diaphragm Bottom Cover | Ductile Iron | QT400-18 |
| 48 | Spring Plate | Steel | SAE 1010 |
| 49 | Diaphragm | Phosphor Bronze | - |
| 50 | Diaphragm Plate | Brass | ASTM B 283 |
| 51 | Pilot Spring | Stainless Steel | AISI 302 |
| 60 | Pilot Gasket | Graphite/Asbestos | AISI 302 |
| 61 | Pilot Mounting Nut | Steel | SAE J 429 Grs |
| 62 | Diaphragm Chamber Nut | Steel | SAE J 429 Grs (Spec: 5/16"-18×1") |
Installation Instructions
Installation Requirements
- The pressure reducing valve should be installed on horizontal piping to ensure even stress distribution and stable operation.
- Installation piping should include bypass and isolation valves for equipment maintenance and inspection.
- A steam trap and strainer must be installed upstream of the valve to remove condensate and debris from the media, protecting the plug from wear.
- At least 10 pipe diameters of straight run should be maintained before and after the downstream pressure sensing line to ensure accurate pressure sensing and avoid interference from pipe elbows, valves, etc.
Caution
Flow calculations are based on external sensing line installation. Without external sensing line, flow will be reduced; at very low downstream pressures, flow reduction can reach up to 30%.
Selection Guide
Flow Chart Usage
- Saturated Steam: Based on upstream pressure, downstream pressure, and required flow rate, find the corresponding point on the flow chart and move vertically down to determine the minimum valve size that meets requirements.
- Superheated Steam: Due to higher specific volume of superheated steam, data from the flow chart requires correction—correction factor for 55°C (100°F) superheat is 0.95, for 110°C (200°F) superheat is 0.9.
Selection Principles
Selection Guidelines
- The calculated CV value for actual operating conditions should be between 20%-80% of the valve's full CV value to ensure valve regulation accuracy and stability.
- For critical applications, precise CV calculation is recommended for sizing to avoid system operation issues due to improper flow matching.
Applications
The 25P Pilot Operated Pressure Reducing Valve provides precise and reliable performance, primarily used in industrial steam systems for applications requiring high-pressure steam reduction to equipment effective working pressure, including but not limited to:
- Steam process systems in chemical and pharmaceutical industries
- Heating equipment in food processing and textile industries
- Steam heating in HVAC systems
- Industrial boiler steam transmission and distribution systems
- Various production equipment requiring stable low-pressure steam supply
