Single Acting Pneumatic Lug Butterfly Valves
A single acting pneumatic lug butterfly valve combines a threaded lug body with a spring-return pneumatic actuator. Placed at a line end or at a point where one side will be removed, the valve moves to its safe position by spring force the moment supply air is lost, preventing the medium from escaping through the open end.
Because the lug body is bolted to each flange separately, equipment on the downstream side of the automated valve can be detached without removing the valve. The rack-and-pinion actuator runs on 2.5–8 bar air, and the solenoid and limit switch fit directly through the ISO 5211 / NAMUR interface.
Main Applications
- Tank and vessel outlets closing on power failure
- End-of-line filling and discharge stations
- Automated valves on pump suction needing one-sided removal during maintenance
- Loading lines on ships and jetties
- Compartment inlets and outlets in treatment basins
- Separation points between fire water and process water
Technical Data
| Valve connection | Lug; threaded lugs |
|---|---|
| Size range | DN25–DN300 |
| Valve pressure class | PN16 |
| Lug threads (PN16) | DN50: 4×M16 · DN80–DN125: 8×M16 |
| Medium temperature | EPDM −10 / +130 °C |
| Actuator | Rack and pinion, single acting, preloaded cartridge springs |
| Supply pressure | 2.5–8 bar |
| Actuator ambient temperature | Standard −20 / +80 °C · low −35 / +80 °C · high −15 / +150 °C |
| End position adjustment | ±5° (opening and closing direction) |
| Interface | ISO 5211 · DIN 3337 · NAMUR |
| Position indicator | Continuous, three-dimensional |
| End-of-line use | Possible; permissible pressure depending on model |
Material Options
| Part | PN16 · GG25 body, stainless disc | PN16 · GG25 body, nickel-plated disc |
|---|---|---|
| Valve body | Grey cast iron GG25, threaded lugs | Grey cast iron GG25, threaded lugs |
| Disc | Stainless steel AISI 316 | Nickel-plated ductile iron GGG-40.3 |
| Valve stem | SS420 | SS420 |
| Valve seat | EPDM | EPDM |
| Actuator body | Aluminium extrusion (ASTM 6005), hard anodised | Aluminium extrusion (ASTM 6005), hard anodised |
| Actuator end caps | Aluminium die-cast, epoxy or polyester powder coated | Aluminium die-cast, epoxy or polyester powder coated |
| Springs | Preloaded cartridge springs, corrosion-protected | Preloaded cartridge springs, corrosion-protected |
On an automated lug valve used at a line end, the open end should be closed with a blind flange for long-term service. The stainless disc type is preferred for chlorinated and mildly corrosive water, the nickel-plated disc type for closed heating and cooling water.
Advantages
Safety at the Open End
- The valve closes by spring when air is lost.
- Uncontrolled draining from the line end is prevented.
Easy Maintenance
- The downstream flange is detached without removing the valve.
- The automation package stays in place.
Reversible Motion
- Piston orientation can be changed.
- Normally closed or open set-up is adjusted on site.
Long Service Life
- Hard anodised body and pistons.
- Low-friction, replaceable bearings.
Construction and Design Features
- Threaded lug valve body
- Single acting pneumatic actuator mounted to the stem via ISO 5211
- Symmetrical pistons and preloaded spring cartridges
- Continuous position indicator and ±5° end position screws
- Solenoid valve on the NAMUR face, limit switch box on top
Request a quote for single acting pneumatic lug butterfly valves by stating size, end-of-line use, safe position, supply air pressure and solenoid voltage.
How to Choose?
- Confirm the body typeChoose a lug body if the valve will remain at a line end or one side will be removed separately.
- Define the failure positionChoose a normally closed spring-return set-up if the line must close on power loss.
- Check spring torqueMake sure the end-of-stroke spring torque covers the valve closing torque at maximum pressure.
- Add accessoriesSpecify a limit switch box for remote monitoring and a NAMUR solenoid valve for control.
Complementary Products
Why ORFA?
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Details →Our Single Acting Pneumatic Lug Butterfly Valves
ORFA supplies single acting pneumatic lug butterfly valves in a range of pressure classes, sizes and connection types to suit your application. Descriptions, technical specifications, materials and dimension tables are available on each detail page.
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