For hygienic processing lines operating in classified hazardous areas, specifying a reliable intrinsically safe valve control unit is non-negotiable. The Alfa Laval ThinkTop® Basic Intrinsically Safe answers that brief with a modular, cost-effective control top that combines proven NAMUR sensing, pneumatic actuation and ATEX certification in a single watertight housing. It is designed to give plant operators continuous, real-time visibility of valve position while meeting the safety requirements of Directive 2014/34/EU.

How the NAMUR feedback sensor delivers real-time valve status

Valve position is detected by an indication pin mounted on the valve stem. Two inductive NAMUR NC sensors with a nominal voltage of 8 V track stem movement and report de-energized and energized valve states. A yellow LED provides local visual confirmation, while the digital signal is passed through a certified electrical barrier to the PLC. Sensor electromagnetic compatibility is verified to EN 60947-5-6 and EN IEC 60947-5-2, and the inductive sensor carries certificate PTB 00 ATEX 2032 X.

ATEX certification for gas and dust atmospheres

The control unit is ATEX evaluated for category 2 equipment in both gas and dust atmospheres: Ex II 2G Ex ib IIC T6 Gb for gas and Ex II 2D Ex ib IIIC T85°C Db for dust. The integrated solenoid valves carry certificate DEKRA 11ATEX0273 X. Together these approvals support installation in hazardous hygienic process areas in compliance with Directive 2014/34/EU.

Plug-and-play fit on Alfa Laval hygienic valves

The ThinkTop Basic Intrinsically Safe mounts directly on the ATEX-evaluated Alfa Laval hygienic valve range with no adaptor required. Compatible valve families include Unique SSV, Unique Mixproof, SRC (except SRC-LS), SMP-SC, SMP-TO and SMP-BC, LKLA-T, Shutter and SBV. This direct fit reduces spare-part complexity and simplifies retrofit projects on existing hygienic skids.

Intrinsically safe PLC integration via electrical barriers

All electrical signals from the control unit must be routed through an electrical barrier — typically a Zener barrier — in the safe area to maintain the intrinsic safe circuit. The barrier must comply with EN 60079-14 and respect the apparatus maximum values: sensor Ui 16 V, Ii 76 mA, Pi 242 mW, Li 100 µH, Ci 100 nF; solenoid Ui 28 V, Ii 225 mA, Pi 1 W, Li 0 µH, Ci 0 nF. The Entity Concept is supported, allowing safe interconnection with associated apparatus not specifically examined as a system, using default cable parameters of 197 pF/m and 0.20 μH/ft when unknown.

Pneumatic actuation with up to two 3/2-way solenoid valves

The unit can be configured with zero, one or two 3/2-way solenoid valves that convert compressed air and the PLC signal into mechanical energy at the pneumatic actuator. Air supply is rated 150–700 kPa (1.5–7 bar / 22–100 psi). A manual hold override is included for commissioning and maintenance, and push-in fittings are available in Ø6 mm or 1/4".

Built for harsh hygienic environments

Construction materials include stainless steel and brass, Black Nylon PA 6 reinforced with stainless steel fibers, and NBR seals. The housing is rated IP66 and IP67 (NEMA 4.4x and 6P) and the unit operates from -10 °C to +45 °C / +14 °F to +113 °F. Compact dimensions — 225 mm height (300 mm clearance), 172 mm width and Ø137 mm — keep the footprint manageable on dense valve manifolds. The result is a low-TCO valve control top that reduces unplanned downtime and streamlines ATEX-compliant hygienic line design.