In many industries, there are certain areas that are classified as hazardous or Ex areas. This is an area that contains, or may contain, combustible substances such as gas, vapour or dust. Typical hazardous areas include coal mines, grain silos, chemical and petroleum plants, offshore and onshore oil and gas rigs, oil refineries, pharmaceutical plants and paint shops.
During the coal mining process, byproducts in the form of coal dust and methane are produced. The build-up of either of these can be extremely dangerous. Even a tiny spark can set off a disastrous explosion. Similarly, grain silo dust ignited by a spark, has led to tragic explosions.
Safety measures in hazardous areas
In order for ignition to occur, two things are needed: the combustible atmosphere as described above, and a trigger i.e. a spark or flame. Remove one or both of these conditions and an explosion cannot occur.
Removing combustible dust and vapour
Ventilation equipment can dilute or remove dangerous substances from an enclosed area and as a result reduce the risk of explosion. This method is extensively used in the mining and chemical industry.
Apart from ‘No Open Flame’ signs, precaution must be taken to prevent electrical equipment from being a source of ignition. A simple electrical switch, for example, can generate an electrical spark every time it is thrown – depending on the type of load. This spark may be enough to act as a trigger for an explosion in a hazardous area. In a similar fashion, sparks can be created by portable electronic devices. In order for devices to be safe for use in hazardous areas, safety precautions have to be built into the design.
Intrinsically safe (IS) instruments
There are several aspects in the design of IS electronic devices, of which reducing or eliminating switch sparking is but one. Other considerations include, fast fuses, controlling component temperatures, eliminating tight component spacing that could lead to a short circuit, and reducing circuit current and energy storage.
R&C Instrumentation is geared to supply a considerable range of intrinsically safe instruments, for instance the Raytek MT4-IS handheld non-contact thermometer for the temperature range -18 to 400°C, the Raytek Mi3-IS 4-wire system fixed pyrometer and the Raytek TX-IS 2-wire loop powered system fixed pyrometer.
As part of the recently launched range of vibration sensors, there is also a wide range of ATEX IEC and Ex certified versions available. Additionally, due to a special request from a mining client, there is now also the UT390B+IS laser distance meter available from stock.
The importance of up-to-date alarm annunciators January 2020, Omniflex Remote Monitoring Specialists
, IS & Ex
At 1.23 pm on Sunday, 24 July 1994, twenty-six people were injured when an explosion erupted through an oil refinery in an otherwise quiet corner of South Wales in the United Kingdom. The site was occupied ...
Read more...Gas detector for multiple applications January 2020, Comtest
, IS & Ex
Comtest, the local representative of Industrial Scientific, global leader in gas detection, has announced a new version of the Ventis Slide-on Pump. The new pump is compatible with both Ventis MX4 and ...
Read more...Light grid with integrated muting unit November 2019, ifm - South Africa
, IS & Ex
The new generation of light grids from ifm electronic allow for the muting mode without an external junction box or a muting relay being required, as they are already integrated into the receiving element. ...
Read more...Vibration measurement in machine maintenance October 2019, R&C Instrumentation
, Maintenance, Test & Measurement, Calibration
Vibration and temperature are the most common parameters measured on process plants for machine maintenance. Temperature measurement has been around for longer, probably because it was available first ...
Read more...Light grid with integrated muting October 2019, ifm - South Africa
, IS & Ex
The new generation of light grids from ifm electronic incorporates muting mode without an external junction box or a muting relay being required, as they are already integrated into the receiving element. ...
Read more...IR thermometers in the steel industry September 2019, R&C Instrumentation
, Temperature Measurement
In many foundry applications, temperature readings show whether processes are operating within their proper ranges, whether a reheater is too cold or too hot, whether a stand needs adjusting, or how much ...
Read more...Taking safety to the next level September 2019, SICK Automation Southern Africa
, IS & Ex
SICK Automation is a world leading manufacturer of sensors, safety systems and automatic identification products. The next step for safety – this core idea therefore underpins the entire design of the ...