Electricity + Control May 2019

Today, sensors need to be able to collect information quickly and accurately.

in specific applications. This precaution will prevent unnecessary complications or unplanned downtime and ensure optimum sensor performance and func- tionality in data collection and transmission. Sophisticated sensing elements are small and fragile devices and innovative engineering is re- quired to ensure that they are housed in appro- priate enclosures that will provide the necessary protection without impeding the functionality of the sensor itself. The long-term stability of sensors is just as im- portant. In many instances, sensors are installed and expected to operate with little intervention over an extensive service life. Again, it is essential to select sensors that, once commissioned, do not require recalibration. This will deliver substantial savings in time and cost and supports a reduced total cost of ownership. Materials of construction could include, for ex- ample, Hastelloy B2, which belongs to the group of highly corrosion-resistant nickel-molybdenum alloys. It is suitable for use in acid as well as media with high temperatures and offers good resistance against corrosion such as pitting, crevice corro- sion, chlorine-induced stress and abrasion and cor- rosion within the heat influence zone. Titanium is used where a lightweight metal offering mechan- ical strength is essential, but it is not suitable for use in environments that do not contain oxygen. It has a well proven track record in the chemical and paper bleaching industries as well as in seawater cooling systems and desalination plants. Impact stainless steel can withstand aggres- sive coolants, lubricants and other acidic condi- tions and it is largely impervious to metal chips, vi- brations and abrasive media. This material is used mainly for EX rated sensors which are installed for gas and dust monitoring in potentially hazardous

over all common Ethernet protocols, over dis- tances of up to 120 m. These protocols typically include Profinet, Ethernet IP, EtherCAT, Ethernet TCP/IP and Ethernet UDP. Materials of construction Another critical factor is that sensors are often placed in challenging operational conditions which necessitate protection against high or low temper- atures, high levels of humidity and moisture, shock and vibration and physical impacts from mechan- ical handling systems. Sensors also need to be able to function dependably in acidic chemicals, abrasive slurries and other such media. Bryant says the evolution of sensors has kept pace with these requirements and a variety of ma- terials of construction are used – including exotic materials and innovative composites – to meet dif- ferent application needs and enable reliable func- tioning in rough industrial environments. It is also important, he says, that the sensor ma- terial is verified individually for its chemical stability

In moving towards Industry 4.0 and embracing the operational efficiencies it offers, a first step would be to get a sensing specialist to assess the facility and implement a phased approach to take the operation to the next level.

Sensing equipment can provide information that supports quality production.

Electricity + Control

MAY 2019

21