Single-Seated Pneumatic Diaphragm Control Valve
Single-Seat Globe · DN25–DN300 · PN16/PN40 · 3-15 psi / 4-20 mA
Reguvale's single-seated pneumatic diaphragm control valve is the workhorse modulating valve for flow, pressure, temperature and level loops in chemical, petrochemical, oil & gas, power and water-treatment plants. A spring-opposed elastomer diaphragm drives a single-piece plug against a contoured seat ring, delivering tight shutoff and a stable characteristic curve across the full 0–100% travel range.
The bodies shown are WCB carbon steel with SS316 trim, PTFE seat and multi-spring diaphragm actuator. Equal-percentage or linear characteristic plugs are interchangeable in the field, and the diaphragm case accepts YT-1000 / YT-1050 pneumatic positioners for 3-15 psi or 4-20 mA signals. Smart digital positioners with HART feedback are available on request.
Standard sizes DN25–DN300 in PN16 / PN40 are kept in stock for fast shipment; ductile-iron, SS304, SS316 or alloy-20 bodies with metal or soft seats are available on request for aggressive service.
Key Features
Tight Shutoff
Single-seat plug-and-ring geometry achieves ANSI Class IV (metal) or Class VI (PTFE) shutoff depending on seat material selection.
Stable Characteristic
Equal-percentage or linear inherent flow characteristic maintained across the full 0-100% stroke for predictable loop tuning.
Field-Serviceable Trim
Plug, seat ring and stem packing can be replaced without removing the body from the line, cutting maintenance time.
Modulating or On/Off
Add a positioner for 3-15 psi / 4-20 mA modulating duty, or operate as a spring-return on/off valve with solenoid pilots.
Wide Material Range
Bodies in WCB, SS304, SS316 or alloy 20; trims in SS316, 17-4PH or Stellite-faced for slurry and corrosive service.
Smart Positioner Ready
Top-mounting interface accepts YT-1000, YT-1050 and digital HART/Profibus positioners with no bracket modification.
Technical Specifications
| Parameter | Specification |
|---|---|
| Body Material | WCB Carbon Steel / SS304 / SS316 / Ductile Iron GGG50 |
| Plug / Trim | SS304 / SS316 / 17-4PH / Stellite Faced |
| Seat Material | PTFE / Metal / EPDM / NBR |
| Body Type | Single-Seat Globe, top-guided |
| Size Range | DN25 – DN300 (1" – 12") |
| Pressure Rating | PN16 / PN40 (ANSI 150 / 300 on request) |
| End Connection | Flanged (ISO 7005-2 / EN 1092-2 / ASME B16.5) |
| Flow Characteristic | Equal-Percentage / Linear / Quick-Opening |
| Actuator Type | Multi-spring diaphragm (pneumatic) |
| Control Signal | 3-15 psi / 4-20 mA / On-Off |
| Positioner | YT-1000 / YT-1050 / Smart digital |
| Temperature | PTFE seat: -40→+180°C | Metal seat: -40→+425°C |
| Leakage Class | Metal seated: ANSI Class IV; Soft seated: ANSI Class VI |
| Standards | IEC 60534 / GB/T 4213 / ANSI/ISA-75 |
| Certification | ISO 9001:2015, SGS MTC available |
Frequently Asked Questions
What is a single-seated pneumatic diaphragm control valve used for?
It is the most common modulating valve in process plants, used for flow, pressure, temperature and level control loops in chemical, oil & gas, power and water-treatment service.
How does the pneumatic diaphragm actuator work?
A spring-opposed elastomer diaphragm converts the 3-15 psi or 4-20 mA signal into a linear stem stroke. Air pressure on the diaphragm pushes the plug down against the spring, opening the valve proportionally to the signal.
Which seat material should I choose?
PTFE for most chemicals up to +180°C with Class VI shutoff.
Metal (SS316 / Stellite) for steam, hot oil and temperatures up to +425°C.
EPDM / NBR for lower-temperature soft service.
Applications & Use Cases
Chemical & Petrochemical
Reactor feed, distillation reflux, transfer line and tank blanketing pressure control.
Steam & Power
Boiler feedwater, superheated steam temperature and turbine bypass control.
Water Treatment
Coagulant dosing, filter inlet pressure, clearwell level and distribution flow control.
Oil & Gas
Separator level, gas gathering pressure reducing and wellhead flow control skids.
