Y43H Piston Type Pressure Reducing Valve
• PN16 / PN25 flanged connection, DN20–DN300
• Self-operated piston type — no external power required
• 3 models: Y43H-16Q (ductile iron), Y43H-16C (cast steel), Y43H-25 (cast steel)
• Outlet: 0.05–1.0 MPa (PN16) / 1.0–1.6 MPa (PN25)
• Deviation: ±0.05 MPa (PN16) / ±0.06 MPa (PN25)
Gaoshan Valve — Y43H Piston Type Pressure Reducing Valve
Model: Y43H-16C / Y43H-16Q / Y43H-25 | Pressure: PN16 / PN25 | Connection: Flanged | Medium: Steam, Air, Gas
Product Overview
The Y43H Piston Type Pressure Reducing Valve is a self-operated pressure regulating valve designed for gas pipelines carrying steam, compressed air, and other gaseous media. Through an adjustable spring-loaded piston mechanism, the valve reduces a higher upstream inlet pressure to a stable, lower downstream outlet pressure. When the inlet pressure or flow rate fluctuates, the valve — driven solely by the energy of the medium itself — automatically maintains the outlet pressure within a tight tolerance band. No external power source, pneumatic supply, or electrical control is required. This makes the Y43H an ideal solution for steam distribution headers, process heating systems, compressed air networks, and industrial gas supply lines where reliable, maintenance-free pressure regulation is essential.
Key Advantages
Self-Operated — No External Power
The valve uses the energy of the flowing medium itself to regulate pressure. No pneumatic supply, electricity, or control system is required — making it ideal for remote locations and steam distribution networks.
Automatic Pressure Regulation
When inlet pressure or flow rate changes, the piston-sensing mechanism instantly adjusts the valve opening to maintain the set outlet pressure. The outlet pressure deviation is held within +/- 0.05 MPa (PN16) or +/- 0.06 MPa (PN25).
Durable Piston-Spring Mechanism
The piston is sealed with an alloy cast iron piston ring for long service life. The main valve spring is chrome-vanadium steel and the regulating spring is silicon-manganese steel — both engineered for high-cycle fatigue resistance.
Three Body Material Options
Available in cast steel (Y43H-16C / Y43H-25) for general service and ductile cast iron (Y43H-16Q) for cost-effective applications. All internal trim parts are stainless steel for corrosion resistance.
Technical Specifications
| Parameter | Y43H-16C / Y43H-16Q | Y43H-25 |
|---|---|---|
| Nominal Pressure | PN16 | PN25 |
| Working Temperature | ≤200°C | ≤350°C |
| Inlet Pressure | ≤1.6 MPa | ≤2.5 MPa |
| Outlet Pressure Range | 0.05 – 1.0 MPa | 1.0 – 1.6 MPa |
| Outlet Pressure Deviation | ±0.05 MPa | ±0.06 MPa |
| Nominal Diameter | DN20 – DN300 | DN20 – DN300 |
| Connection Type | Flanged (RF) | |
| Suitable Medium | Steam, compressed air, and other non-corrosive gases | |
| Regulation Type | Self-operated piston type (no external power required) | |
Main Parts & Materials
| Part Name | Y43H-16Q | Y43H-16C | Y43H-25 |
|---|---|---|---|
| Body, Bonnet, Lower Bonnet | Ductile Cast Iron | Cast Steel | Cast Steel |
| Main Disc & Seat | Stainless Steel | Stainless Steel | Stainless Steel |
| Auxiliary Disc & Seat | Stainless Steel | Stainless Steel | Stainless Steel |
| Main Valve Spring | Chrome-Vanadium Steel | Chrome-Vanadium Steel | Chrome-Vanadium Steel |
| Regulating Spring | Silicon-Manganese Steel | Silicon-Manganese Steel | Silicon-Manganese Steel |
| Piston Ring | Alloy Cast Iron | Alloy Cast Iron | Alloy Cast Iron |
| Diaphragm | Stainless Steel | Stainless Steel | Stainless Steel |
Model Selection
| Model | Body Material | Pressure Class | Temp. Limit | Outlet Range |
|---|---|---|---|---|
| Y43H-16Q | Ductile Cast Iron | PN16 | ≤200°C | 0.05 – 1.0 MPa |
| Y43H-16C | Cast Steel | PN16 | ≤200°C | 0.05 – 1.0 MPa |
| Y43H-25 | Cast Steel | PN25 | ≤350°C | 1.0 – 1.6 MPa |
How It Works
The Y43H piston type pressure reducing valve operates on a self-balancing principle. High-pressure medium enters the valve inlet and passes through the throttling gap between the main disc and seat, where its pressure is reduced. The downstream (reduced) pressure is sensed through a pilot passage that acts on the underside of the piston and diaphragm assembly. This downstream pressure force is balanced against the adjustable regulating spring force. When the downstream pressure rises above the set point, the piston assembly moves upward, reducing the main disc opening to throttle flow. When downstream pressure drops, the spring pushes the piston downward, opening the main disc further. This continuous feedback loop keeps the outlet pressure stable regardless of inlet pressure fluctuations or downstream demand changes.
Y43H Piston Type Pressure Reducing Valve — Structure & Working Principle Diagram
Dimensions (mm) & Weight (kg)
| DN | L | H | H1 | Weight (16Q/16C) |
|---|---|---|---|---|
| 20 | 160 | 101 | 312 | 14 / 15 |
| 25 | 180 | 101 | 315 | 16 / 16 |
| 32 | 200 | 107 | 320 | 16 / 19 |
| 40 | 220 | 113 | 325 | 22 / 23 |
| 50 | 250 | 113 | 335 | 30 / 31 |
| 65 | 280 | 140 | 365 | 35 |
| 80 | 310 | 150 | 385 | 52 |
| 100 | 350 | 150 | 385 | 58 / 59 |
| 125 | 400 | 185 | 425 | 82 / 86 |
| 150 | 450 | 210 | 445 | 96 / 98 |
| 200 | 500 | 210 | 445 | 125 / 130 |
| 250 | 650 | 350 | 850 | 490 |
| 300 | 800 | 390 | 880 | 770 |
*Note: L = Face-to-face length, H = Center height to center of connection, H1 = Total height. Flange dimensions per GB/T 9113 / JB/T 79. For Y43H-25, dimensions are identical to Y43H-16C/16Q for the same DN sizes.
Installation Guidelines
- Install on a horizontal pipeline with the regulating spring housing in a vertical upright position to ensure proper operation
- Install a strainer (Y-type or T-type) upstream of the valve to protect the piston and seat from debris and scale
- Install a pressure gauge on both the upstream and downstream sides for set-point adjustment and monitoring
- Provide a bypass line with a globe valve around the pressure reducing valve for maintenance access without plant shutdown
- Allow at least 5x pipe diameters of straight run upstream and downstream for accurate pressure sensing
- When commissioning, set the regulating spring to minimum tension first, then gradually increase while monitoring the downstream pressure gauge
- For steam service, install a steam trap upstream to remove condensate and prevent water hammer damage
- Inspect and clean the piston ring and diaphragm annually for optimal performance
Application Fields
Compressed Air Networks
Process Heating
Textile & Dyeing
Food & Beverage
Pharmaceutical
Chemical Processing
HVAC & Building Services
Quality Standards & Certifications
Additional Certifications & Standards
- Design & Manufacture: GB/T 12244 (Pressure Reducing Valve)
- Face-to-Face: GB/T 12221
- Flange Ends: GB/T 9113 / JB/T 79
- Test & Inspection: GB/T 13927 / GB/T 12245
- ISO 9001 Quality Management System
- TS Special Equipment Manufacturing License
Packaging & Shipping
Each pressure reducing valve is individually packed with protective end caps over the flange faces, sealed in a poly bag with desiccant, and secured in a plywood case or export-standard wooden crate. The regulating spring housing and pilot assembly are packed with additional impact protection. All shipments include a packing list, material certificate, hydrostatic test report, and performance curve (pressure vs. flow). We support FOB, CIF, DAP, and other Incoterms.
After-Sales Service
- 18-month warranty from date of delivery
- Technical support for set-point adjustment and commissioning
- Spare parts supply for piston ring, diaphragm, springs, and trim components
- On-site inspection, troubleshooting, and repair service upon request
Request a Quote
Need a specific pressure range or material option? Contact Gaoshan Valve today for competitive pricing, sizing assistance, and technical support.