Alfa Laval Indication Units for LKB/LKLA, SRC, ARC, & ARC-SB Valves

Alfa Laval's laterally mounted indication units are a simple option for providing valve position indication for Alfa Laval LKB/LKLA, SRC, ARC and ARC-SB air operated valves. These indication units are installed laterally between the air operated actuator and the valve.

All switches are EMC approved according to the following standards:

  • EN 50081-1, Generic emission standard, commercial and light industry
  • EN 50082-2, Generic immunity standard, industrial environment
  • PR EN 60947-5-2, Product family standard, proximity switches
  • KA 2791.30 section 5.5 EMC, Tetra Pak Corporate standard

The pull-up or pull-down resistance in the input stage of the PLC must be 1 – 10 k ohms to ensure a proper reading of the signal from the sensors. The wire connection can be different.



A micro switch can be compared with a standard light switch, but in a very small size and light weight, also called a sub-miniature switch. It is activated mechanically by a roller leaf. The standard function is normally open (NO) or normally closed (NC) and is always a digital signal (on/off).

The features of an environment-proof, sealed sub-miniature switch are:

  • Small size
  • Light weight
  • Ample electrical capacity
  • Precision operation
  • Long life

The micro switch used in indication units is enclosed within a corrosion-resistant aluminium housing to seal the switch contact and terminals against contamination.


This type of switch is a non-contact, electronic switch. It consists of an oscillator, which creates high frequency electromagnetic fields that radiate from the sensing face of the switch. Every approaching conductive metal (damping target) causes a reduction of the electromagnetic field. The result is a voltage change of the oscillator. This analogue signal is converted by a trigger circuit into an on/off signal and the output is amplified.


Hall proximity switches are also non-contact, electronic switching elements. The sensor registers a magnetic field (north pole) and consists of a Hall element (a type of a transistor) matching part, an amplifier, and an output part. The output signal is always digital and on/off. The switching frequency is higher than the normal inductive switch or the micro switch. The Hall proximity switch is ideal for modern computer processing. NPN and PNP are two types of transistors; the difference is the composition of positive or negative semiconductive materials.

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Indication Units for LKB/LKLA, SRC, ARC, & ARC-SB Valves (Alfa Laval)

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