Choose by the condition on your valve — corrosive atmosphere, hazardous area, small stroke, hot vibrating skid or a digital plant — not by compromise. Same control core, same spare parts, same mounting platform.
Most specification mistakes happen before anyone looks at a model number — the positioner is chosen for the plant, not for the valve it has to move. Start with the valve.
The default duty: feed, steam, cooling water, reflux. Linear stem, lever or direct feedback, highest resolution at small openings.
Short 90° travel with high torque and low friction breakaway. Rotary feedback, and the housing can be rotated 180° to clear the pipework.
Quarter-turn, often on/off or ESD duty. Put the electronics away from the vibration and heat of the pipe: sensor on a bracket, 10 m remote.
Small strokes and small volumes: dosing, pharma, water treatment. The low-flow version keeps the pilot stable when the actuator only moves a few millimetres.
Filter by what your installation actually looks like. Every configuration below shares the same 4–20 mA / HART 7 control core.
Epoxy-coated aluminum housing. The default choice for refinery, power and utility modulating loops.
For salt spray, chloride atmospheres, washdown areas and vibrating skids — positioner body mounted away from the valve.
Flameproof enclosure for Zone 1 / Zone 2 process areas, with LCD and local push-buttons for calibration without opening the cover.
For small globe, diaphragm and angle valves in dosing, pharma and fine-chemical service where standard positioners hunt.
Positioner body mounted away from hot, vibrating or hard-to-reach valves; feedback unit stays on the stem.
Rotate the housing 180° to fit tight spaces and awkward actuator orientations without custom brackets.
New-generation platform supporting Ethernet-APL field connectivity — Ethernet to the valve, without gateways on the marshalling side.
Photographs from our own production line — not renders. Three details that decide whether a positioner survives ten years on a valve.
● standard · ○ option · — not applicable. Anything marked ○ is quoted on request with the same lead time as the standard unit.
| Feature | C41 Standard |
C45 316L split |
Ex db Flameproof |
SFA Low flow |
Split + feedback |
180° Rotatable |
APL Ethernet |
|---|---|---|---|---|---|---|---|
| Die-cast aluminum housing | ● | — | ● | ● | ● | ● | ● |
| 316L stainless housing | — | ● | — | — | ○ | — | — |
| 4–20 mA input + HART 7 | ● | ● | ● | ● | ● | ● | ● |
| Profibus-PA / Foundation Fieldbus | ○ | ○ | ○ | ○ | ○ | ○ | ○ |
| Ethernet-APL connectivity | — | — | — | — | — | — | ● |
| Flameproof enclosure Ex db | — | — | ● | — | — | — | — |
| Intrinsic safety Ex ia IIC T4 | ○ | ○ | — | ○ | ○ | ○ | ○ |
| Split mounting, remote electronics | — | ● | — | — | ● | — | — |
| Low-flow / short-stroke tuning | — | — | — | ● | — | — | — |
| 4–20 mA position feedback | ○ | ● | ○ | ○ | ● | ○ | ○ |
| LCD + local push-buttons | ● | ● | ● | ● | ● | ● | ● |
| SIL3 capable | ● | ● | ● | ● | ● | ● | ● |
| Typical service | Refinery & utility loops | Offshore, chloride | Zone 1/2, gas & oil | Dosing, pharma | Hot, vibrating skids | Cramped retrofits | New-build digital plant |
The interface is the same across the range — the question is where the electronics should live.
Direct on the actuator yoke, feedback taken from the stem. Shortest air path, fastest commissioning, lowest cost — the right answer for ordinary indoor and sheltered outdoor valves.
Electronics on a bracket or handrail, feedback unit on the stem, connected by cable. For radiant heat, heavy vibration, or valves 6 m up a structure.
Rotate the housing to clear pipe racks and insulation; internal air passages remove external tubing. Fewer joints to leak, fewer to check at turnaround.
Values below apply to the standard platform. Certificates and test reports are supplied with every offer — your engineers can verify them against the zone and SIL requirements directly.
| Input signal | 4–20 mA (stepping control input option) |
|---|---|
| Communication | HART 7 · Profibus-PA · Foundation Fieldbus · LPA bus |
| Air supply | 1.4–6 bar, instrument air (oil-free, water-free, dust-free) |
| Steady-state air consumption | 36 L/h |
| Control accuracy | 0.1–0.3% F.S. · repeatability 0.2% F.S. |
| Ambient temperature | Standard −30 to +70 °C · low-temperature −40 to +60 °C · custom down to −60 °C |
| Enclosure | IP66 · die-cast aluminum (epoxy coated) or 316L stainless steel |
| Safety | SIL3 (TÜV SÜD certificate) · partial stroke test 10–30% |
| Hazardous area | Intrinsic safety and flameproof versions; ATEX, IECEx, EAC, NEPSI certificates |
| Travel | Linear and rotary, direct or reverse acting; 180° rotatable mounting |
| Failure behaviour | Fail-in-place on loss of air, power or signal — no external lockup stack required |
| Calibration | One-touch auto-calibration, 3–5 min (longer for complex actuators) |
| Diagnostics | HART diagnostics, LCD display, upper/lower limit contact outputs, 4–20 mA feedback option |
| Design life | 10 years |
Note: performance figures are typical values for the standard platform under specified conditions. Confirm exact configuration against the datasheet issued with your quotation.
One platform, twelve option groups. Send us the ones that matter and we will build the code — you should not have to decode our catalogue to get the right device.
| Option group | Available choices |
|---|---|
| Housing / material | C41 die-cast aluminium, epoxy coated · C45 316L stainless steel |
| Special version | Standard · SFA low-flow (small valves, dosing, diaphragm) |
| Communication | 4–20 mA · 4–20 mA + HART 7 · RS-485 · Profibus-PA · Foundation Fieldbus · Ethernet-APL |
| In-service replacement | Standard · parameter-copy version (swap without full auto-calibration) |
| Action | Linear stroke · rotary (0–120°) |
| Actuator type | Single acting · double acting |
| Area classification | Non-hazardous · Ex ia IIC T4 (intrinsic safety) · Ex db IIC T6 (flameproof) · Ex tD dust · combined gas + dust |
| Position feedback | None · 4–20 mA retransmission |
| Limit contacts | None · built-in upper / lower contact module |
| Mounting bracket | Not required · standard linear · standard rotary · custom bracket |
| Mounting style | Integral · split-mount (remote sensor) |
| Failure behaviour | Fail-in-place · fail-locked · air-to-open / air-to-close |
| Pressure gauge | None · with gauge block |
Option availability depends on housing and certificate. Example of a delivered code: a 316L split-mount, HART 7, single-acting, Ex db, with limit contacts and 4–20 mA feedback — we will issue the exact string on the datasheet with your quotation.
Selected from the same family so air circuits, mounting and spares stay consistent across the plant.
Filters and regulates instrument air ahead of the positioner — the first line of defence against oily header air.
Faster stroking on large actuators without sacrificing stability.
Independent 4–20 mA position feedback for existing installations.
Air lockup for fail-safe action when the positioner's built-in fail-in-place is not the whole story.
TOP series solenoids for ESD and on/off duty, matched to the same air circuit.
Private-label and custom configurations for valve and actuator manufacturers — housing, label, packaging, protocol.
Send the valve type, actuator, stroke and service conditions — we'll specify it and say plainly where our product is not the right answer.
Ask an application engineer