Valve Position Monitors

Enicstra stocks complete valve position monitor housings — the packaged solutions that mount on top of rotary valve actuators and include the cam mechanism, switches or sensors, indicator dome (visual open/closed indication), terminal strip or fieldbus interface, and the NEMA-rated enclosure. Valve position monitors are sold as complete units sized to match common valve actuator interfaces (NAMUR mounting standard).

Brands carried include Topworx D-series and TXP, Stonel Falcon and Eclipse, Soldo, Westlock Controls, Smar BT-LOGIC, ASCO ValPlus, Numatics ServoNet, and Indelac Controls. Obsolete valve position monitors — discontinued Topworx D first generations, retired Stonel Falcon early codes, end-of-life ASCO ValPlus — are sourced through our supplier network. Each unit is bench-tested for power-up, switch action, and dome indication and ships with a 12-month functional warranty.

For an obsolete valve position monitor, send the OEM part number for a quote within 1–2 business days.

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Valve Position Monitors

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Buying guide

Choosing Valve Position Monitors components

Valve position monitor selection comes down to the actuator mounting interface, the number and type of internal switches/sensors, the communication output to the control system, and the hazardous-area certification needed. The monitor housing is sized for a specific actuator class — substituting across classes requires new mounting hardware.

Specs to confirm before ordering:

Mounting interface: NAMUR VDI/VDE 3845 standard (most modern actuators), or actuator-specific bracket
Shaft adapter: square drive size and depth to match the actuator's drive shaft
Number and type of switches: 2 mechanical microswitches (most basic), 2 inductive proximity, 2 Namur sensors, or hybrid configurations
Indicator dome: standard red/green visual, beacon-style high-visibility, optional dome heater for cold environments
Enclosure rating: NEMA 4X stainless or aluminum (standard), NEMA 7 explosion-proof, ATEX/IECEx zones
Communication: hardwired contacts to terminal strip, AS-Interface, DeviceNet, Profibus PA, Foundation Fieldbus, IO-Link, HART, Profinet
Solenoid manifold: integrated 4-way valve for piloting the pneumatic actuator (often coded as "ValTop", "Smart" variants)
Optional valve positioner for modulating service vs. simple open/close

Common gotchas: NAMUR mounting is dimensionally standardized but actuator manufacturers sometimes deviate by a few millimeters — verify the actual bolt pattern and shaft height before ordering. Hazardous-area monitors require specific cable glands and wiring methods; the certification is voided if wiring departs from the listing. Fieldbus monitors (AS-i, DeviceNet, Profibus PA) require both the matching network on the PLC side and an address set on the monitor — out-of-the-box devices typically have default addresses that must be configured.

Typical applications: open/closed status of process valves on water, oil and gas, chemical, and pharmaceutical plants; quarter-turn actuator position confirmation; manifold-mounted monitors that combine solenoid piloting with position feedback in a single device; and explosion-proof monitors on offshore and refinery applications.

For obsolete valve position monitors, send the OEM part number for a sourcing quote.

Related categories Frequently asked questions

Do you stock obsolete Topworx and Stonel monitors?

Yes. Discontinued Topworx D-series first generations, retired Stonel Falcon early codes, end-of-life ASCO ValPlus, and earlier Soldo monitors are sourced through our supplier network.

Will the monitor mount on my actuator?

If both have NAMUR VDI/VDE 3845 mounting and the same shaft height/drive size, yes. For non-NAMUR or older proprietary mountings, a bracket kit may be needed. Send the actuator manufacturer and model with your request.

Hardwired vs. fieldbus monitor — which is better?

Hardwired (NO/NC contact outputs to terminal strip) is simpler and works with any control system. Fieldbus monitors (AS-i, Profibus PA, Foundation Fieldbus) save wiring on large plants with hundreds of valves but require matching infrastructure.

Is the solenoid included with manifold-style monitors?

For combined monitor+solenoid units (e.g., Topworx DXP, Stonel Eclipse with integrated solenoid), yes. For monitor-only units, the solenoid is separate. We will state the configuration on each listing.

Are explosion-proof versions available?

Yes. NEMA 7 (US explosion-proof), ATEX (Europe), and IECEx (international) certified versions are routinely sourced. Match the original certification rating to keep the area classification valid.

What is the warranty?

12-month functional warranty. Damage from over-pressure on integrated solenoid, miswiring, or installation that violates the certification listing is not covered.