Authored by Michel Vandeweyer | Explosion Safety Consultant from ISMA Explosion Safety Consultancy
ISMA specialises in explosion safety, mainly of gas and dust, and static electricity and are the consultancy arm of StuvEx who designs, implements and engineers industrial fire and explosion protection systems.
An electrostatic discharge can occur in different locations and at different times: Think of the sweater you take off in the winter, or the shock you feel when you touch the car, sometimes you get a shock when you shake someone’s hand.
Why is it that we so often have to deal with electrostatic discharges, without even realising it? A discharge can only occur after an object or surface has been charged.
Charging of an Object or Surface
A charged object can be created in three different ways:
The last two phenomena can only occur in the presence of an already charged object. The first phenomenon, triboelectric charging, takes place in the event of loss of contact between two surfaces. The most known source of triboelectric charging is friction, but also in absence of intense friction, charged surfaces can arise (e.g. removing a plastic foil from a metal plate).
âž¡ Thorne & Derrick are the Exclusive UK Partner for the StuvEx range of Static Earthing & Bonding Systems – our Trained Sales Engineers provide customer service excellence to clients working in hazardous area locations.
The team visited the StuvEx HQ in Belgium to undertake advanced Technical Product Training. During the training they had front row seats to a live demo conducted by Michel Vandeweyer. The below video shows the result of an explosion caused by static.
The fuel for this explosion you ask? 1 Teaspoon of sugar! Knowledge on risks associated with dust atmospheres is poor in comparison to gas atmospheres. Couple that with a poor understanding of risks associated with static electricity and you have a recipe for disaster.
This discharge occurs with highly charged and pointed objects. The charge is concentrated at the tip, resulting in a minor electric field. This electric field causes an ionization of the air.
Corona discharges have a very low energy content: less than 0.1 mJ. This ensures that Corona discharges are almost never a significant ignition source.
These discharges occur with highly charged, poorly conductive surfaces: think of ordinary clothing, a carpet, a plastic bag, … The charge stored on the poorly conductive surface can only discharge at the point where another object at a different potential comes close.
The energy of this discharge is therefore limited, but significantly greater than the Corona discharge: a maximum of 4 mJ.
This ensures that brush discharges are almost never the ignition source of a dust explosion. However, explosive gas/air mixtures are much more susceptible to ignition. A brush discharge is dangerous for almost all flammable gas/air mixtures.
Brush discharges can also be caused by the movement of non-conductive clothing (the classic example is a fleece sweater). Examples regarding measures to prevent the risk of brush discharges are
When two conductive objects, with a different charge level, come close to each other, this charge will equalise across both objects by means of a spark discharge. The energy of this spark is therefore dependent on the charge level, and the possible charge present depends on the size of both objects (the smallest object is decisive). The larger the object, the greater the possible energy content of the resulting spark.
Thus, the typical energy content varies greatly. For example, a charged tanker truck can create spark discharges up to 100 mJ.
To prevent this, conductors must be connected, either to each other (equipotential connections over flanges, for example), or to the earth.
Operators also act as conductors. For this reason, it is required to use anti-static footwear, in addition to the use of anti-static clothing. The floors should consist either out of metal gratings or of other materials like concrete that are sufficiently dissipative to discharge the load. The use of non-conductive floor coatings (e.g. Epoxy) or working on a plastic sheet is generally not permitted in ATEX-areas.
If a type-C FIBC (bigbag) is used, it must be earthed to avoid spark discharges, since the FIBC is a conductor.
Propagating Brush Discharges are the most dangerous and powerful discharges that can take place in installations. The energy content of this phenomenon can be > 1000 mJ. These occur when a layered structure of conductors and insulators is created, for example by coating metal or a metal reinforcement in a plastic flexible, and is most easily conceived as a capacitor: The charge continues until it has enough energy to shoot through the insulator towards the conductor.
An important measure in this respect is the use of antistatic hoses in a pneumatic conveyor. Grounding the metal reinforcement is insufficient, and will even facilitate the propagating brush discharge.
A type B-FIBC (bigbag) is used to avoid the formation of propagating brush discharges due to fast emptying/filling. (However, a type B is still able to form a brush discharge, so it should only be used in dust-zones, not in gas zones).
A relatively newly discovered phenomenon is a cone discharge. When a poorly conductive powder is blown neumatically to a silo, a cone will form here. Since the electrical charge is always concentrated on the on the surface on the bulk material, a magnetic field arises above the product cone, which may consequently lead to discharges towards the silo wall. The energy content of this depends on the silo diameter and the average particle size of the powder.
The greatest danger occurs with a large silo diameter and a mixture of large and fine particles, or even worst when flammable gases are present. In order to make a correct assessment of the risk, it is first important to know the specific conductivity of the product. Further preventive measures include, for example, working with earthing rods to virtually reduce the silo diameter. Cone discharges may equally arise in silos filled by gravity.
The formula to calculate the maximum of a cone discharge is given as follows:
E = 5.22 • D3.36 • d1.462
with
D = the diameter of the silo in metres (m) (valid until D = 3 m, the maximum value in the testing). If the silo is made of non-conductive material, (e.g. composite), the silo diameter must be doubled in this formula.
d = the (average) particle size of the particles conveyed into the silo in mm) (valid until d = 3 mm, the maximum value in the testing).
As long as the resulting E is higher than the MIE, ignition due to cone discharges can be excluded. IEC/TS60079-32-1 includes decision trees to evaluate whether the cone discharge is potentially dangerous.
If the silo is made out of non-conductive material, the silo diameter used in the formula must be doubled.
ISMA specialises in process explosion safety consulting. Activities include risk assessment of dust and gas explosive atmospheres, predicting explosion effects, and post-incident analysis in a wide variety of industries. ISMA also shares its expertise in various expert groups. Over 5,000 installations in various industries have been assessed by ISMA since the start of its activities in 1984.
Explosion Protection | Control of Electrostatic Ignition Risks in Hazardous Areas
Should you require any customer support or service to enable the selection or specification of the correct Static Earthing Systems for use in explosive atmospheres please do not hesitate to contact us.
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Specialist Distributors of Electrical Heating, Lighting, Power & Process Instrumentation Equipment with ATEX IECEx Certification and DSEAR Regulatory Compliance to deliver significant safety and reliability improvements in the Industrial, Explosive Atmosphere & Energy sectors. Based in the UK, we are highly customer responsive and absolutely committed to providing a world-class service.
Since 1985, we have provided expert technical support and express delivery from extensive UK stocks to world-wide destinations.
Electrical Trace Heating Solutions For The Chocolate Industry
Keeping the perfect temperature is not just a matter of taste but a crucial element that defines the quality of the end product. The journey from raw cocoa to the silky-smooth chocolate bar requires temperature control, and this is where electrical heat tracing (EHT) systems step in.
Importance of Temperature Control: Chocolate is a delicate creation that demands precise temperature control throughout its production process. Any fluctuation in temperature can lead to undesirable outcomes such as crystallisation, texture variations, or compromised taste. To ensure the chocolate flows seamlessly through every stage of production, from pipes to dosing machines, a constant and fluidic state is paramount.
Role of Electrical Heat Tracing Systems: Electrical heat tracing systems play a pivotal role in maintaining the optimal temperature required for chocolate production. These systems are responsible for ensuring that the chocolate remains fluid and consistent as it moves through various stages, including pipes, valves, pumps, vessels, silos, processing plants, extraction points, dosing, and filling machines.
Single-Source Solution: Choosing the right partner for implementing electrical heat tracing systems is crucial for the chocolate industry. Eltherm stands out as a reliable single-source solution for the engineering, planning, installation, and commissioning of complete EHT systems. What sets Eltherm apart is its in-house engineering and production facilities for EHT products and systems.
Reliability and Uninterrupted Performance: The integration of Eltherm’s EHT systems ensures a seamless chain of heating performance, guaranteeing the chocolate’s uninterrupted flow and consistency. The reliability of these systems is crucial in avoiding downtimes in production, as any interruption can lead to not only financial losses but also a compromise in the quality of the final product.
In the world of chocolate production, where precision and consistency are paramount, Eltherm’s electrical heat tracing solutions emerge as the golden ticket to success.
However, by entrusting the entire process to a single-source solution, chocolate manufacturers can ensure that their product is not only a feast for the taste buds but also a testament to the reliability and efficiency of modern electrical heating technology.
Thorne & Derrick provide a complete portfolio of Electric Process & Trace Heating Solutions for Industrial, Hazardous Area & Explosive Atmospheres,
Specialist Distributors of Electrical Heating, Lighting, Power & Process Instrumentation Equipment to deliver significant safety and reliability improvements in the Industrial, Explosive Atmosphere & Energy sectors.
Your proactive problem solvers experienced in succession planning for the replacement of obsolete, non-conformant and legacy equipment in hazardous areas with ATEX & IECEx Certification & DSEAR Regulatory Compliance.
Industries Supplied | Process, Oil & Gas, Petrochemical, Utility (Water, Gas & Electricity), Food & Beverage, Pharmaceutical, Renewable, Rail, Datacentre, Battery Storage
Product Categories | Electric Heating | Lighting | Control Panels | Confined Space Safety | Plugs & Sockets | Isolators | Enclosures & Junction Boxes | Control Stations | Motor Starters Gas Detection | Security Access Control | Duct Seals | Cable Accessories LV HV | Earthing & Lightning Protection | Feeder Pillars | High Voltage Electrical Equipment | Joints Terminations Connectors MV HV
Power Station Trace Heating
Thorne & Derrick together with Eltherm UK are able to provide custom-engineered trace heating solutions and systems to power stations worldwide. This includes aiding with maintenance work and providing site health services to ensure each power station is operating effectively and efficiently. Together we are able to provide a maintenance, repair and operations programme offering a comprehensive range of trace heating products and electric control and monitoring equipment to global trace heating projects,
In an industrial setting, maintaining the efficiency and reliability of heat tracing systems is crucial for smooth operations, especially during critical periods like winter. Furthermore, Eltherm helps in recognising the significance of proactive maintenance to prevent downtime and ensure optimal performance.
Power station trace heating systems prevent freezing, maintain viscosity, and ensure product quality. However, without proper maintenance, they can become inefficient or fail, leading to costly downtime and potential safety hazards.
Thorne & Derrick specialise in providing specialist heating for industrial and hazardous areas including Eltherm’s heat tracing cables and heated hoses.
As Eltherm UK Ltd’s Master Distributor of Heat Tracing Cables & Systems  for the commercial, industrial, and hazardous area industries, Thorne & Derrick can deliver significant industry benefits and value-added service to you and your company. Our Strategic Partnership can help to maximise uptime and optimise revenue of your business.
Together. we have vast experience maintaining and upgrading heat tracing systems covering all applications and industries, and by listening to our customers’ requirements and concerns, we are able to offer a tailor-made approach that leads to system effectiveness. With the UK’s largest stock holding, we can supply trace heating solutions to quickly to keep you operational all year round.
Understanding the condition of the heat tracing system installed on site is vital. If any remedial work is required it can be planned and budgeted for in an organised manner, helping you to be cost effective and preventing unforeseen issues during critical winter months.
Overall, the utilisation of trace heating cables in power stations offers a comprehensive solution to address concerns related to power shutdown prevention, maintenance, and security, ultimately improving the reliability and resilience of the power plant operation.
Custom Engineered Trace Heating Systems and Solutions
Thorne & Derrick provide a complete portfolio of Electric Process & Trace Heating Solutions for Industrial, Hazardous Area & Explosive Atmospheres,
Specialist Distributors of Electrical Heating, Lighting, Power & Process Instrumentation Equipment to deliver significant safety and reliability improvements in the Industrial, Explosive Atmosphere & Energy sectors.
Your proactive problem solvers experienced in succession planning for the replacement of obsolete, non-conformant and legacy equipment in hazardous areas with ATEX & IECEx Certification & DSEAR Regulatory Compliance.
Industries Supplied | Process, Oil & Gas, Petrochemical, Utility (Water, Gas & Electricity), Food & Beverage, Pharmaceutical, Renewable, Rail, Datacentre, Battery Storage
Product Categories | Electric Heating | Lighting | Control Panels | Confined Space Safety | Plugs & Sockets | Isolators | Enclosures & Junction Boxes | Control Stations | Motor Starters Gas Detection | Security Access Control | Duct Seals | Cable Accessories LV HV | Earthing & Lightning Protection | Feeder Pillars | High Voltage Electrical Equipment | Joints Terminations Connectors MV HV
RAYTEC SPZ-WL84
The existing installation Raytec predominantly used 2x58W T8 fluorescent fittings, mounted 4.1m above the factory floor, combined with emergency twin spot style fittings to provide backup illumination in the event of mains power being lost.Â
With many of the old fluorescent tubes degrading and beginning to ‘yellow’, frequent maintenance and relamping had been required to keep the illumination to an acceptable level. Despite this ongoing maintenance, illumination uniformity was poor with several dark spots around the factory floor. As a result, there was a need for additional task lighting at bench level to assist the operators. Â
RAYTEC Linear Lighting
However with the supply of fluorescent tubes being banned from September 2023, the need to upgrade the lighting system to LED technology was more pressing than ever. Â
Additionally another issue was the layout of the luminaires. Having been first installed by a previous occupier of the building, the luminaires did not align with the racking located at one side of the factory floor which is used to store parts used by operators during production. So this meant illumination between the racking was below the desired levels and also caused an obstruction which limited the height of the racking.
These SPZ-WL84 Light fittings are globally certified to Zone 2 offering long life LED Technology.
This range is manufactured by Raytec and distributed by Thorne and Derrick and are designed for new hazardous area installations or to retrofit existing fluorescent installations which require high performance, high reliability and white light illumination in potentially explosive atmospheres.
Secondly, Raytec’s URBAN Linear luminaires are specifically designed for Industrial applications, were used to replace the existing fluorescent fittings on a 1-for-1 basis. While the new installation used the same number of fittings, the more powerful URBAN luminaires meant smaller, more efficient units could be installed in place of the larger 2x58W (5ft) fluorescents.
A mix of URBAN Linear WL84 (36W, 2ft) and WL168 (72W, 4ft) luminaires were deployed across the installation.Â
In conclusion, the URBAN LED luminaires significantly improved the quality of illumination, increasing average lux levels from 300lx to 400lx with improved uniformity. The extent of the upgrade means the reliance on task lighting is significantly reduced.  Â
Further Reading
More case studies
Thorne & Derrick provide a complete portfolio of Electric Process & Trace Heating Solutions for Industrial, Hazardous Area & Explosive Atmospheres,
Specialist Distributors of Electrical Heating, Lighting, Power & Process Instrumentation Equipment to deliver significant safety and reliability improvements in the Industrial, Explosive Atmosphere & Energy sectors.
Your proactive problem solvers experienced in succession planning for the replacement of obsolete, non-conformant and legacy equipment in hazardous areas with ATEX & IECEx Certification & DSEAR Regulatory Compliance.
Industries Supplied | Process, Oil & Gas, Petrochemical, Utility (Water, Gas & Electricity), Food & Beverage, Pharmaceutical, Renewable, Rail, Datacentre, Battery Storage
Product Categories | Electric Heating | Lighting | Control Panels | Confined Space Safety | Plugs & Sockets | Isolators | Enclosures & Junction Boxes | Control Stations | Motor Starters Gas Detection | Security Access Control | Duct Seals | Cable Accessories LV HV | Earthing & Lightning Protection | Feeder Pillars | High Voltage Electrical Equipment | Joints Terminations Connectors MV HV
Eltherm Heating Hoses
Firstly pressure hoses serve to heat media, maintain a constant temperature and transport media such as the following without heat loss: oil, grease, wax, resin, tar, paint, water, glue, plastic, casting compound, food and many more. Eltherm’s heated hose is mounted on movable system and machine parts in most cases and the temperature ranges up to 250 °C standard.
Moreover the medium is only free flowing at a specific temperature or it only reaches its specific processing properties in a certain temperature range. In addition, flexible means of transport are required in the processing of these media due to moving plant components, which is why its ideal.
Eltherm Heated Hoses
Heated hoses are the ideal solution for the reliable transfer and transportation of liquids or gases without any loss of heat in both safe and hazardous areas. The maintain temperature required, power, application and outer protection material will determine the choice of hose. Typical applications include gas analysis, hot melt machines, bitumen transfer lines, heavy oil transfer and wax processing equipment.
Gas substances are typically channelled between the measurement point and the analysis instrument in the analysis technique such as refineries, flue gas, mechanical engineering, chemical industry and the motor industry. For many applications the gas must have freeze protection, be protected against condensation or guarantee a constant temperature of up to 250°C.
A heated hose can be used to heat up, to prevent heat loss and to transport media such as grease, wax, oils, water, glue, foodstuffs etc – it is vital to keep these products in a liquid form.
Furthermore, Optimum heating cable output on the carrier hose is achieved by using Eltherm standard hoses which are configured to include bifilar heating cables and special spacers.These are also distributed by Thorne and Derrick.
Secondly by creating spatial density in the hose that carries the heating cable ensures perfectly homogeneous heat distribution throughout the hose whilst achieving optimum element loading. The additional glass-fibre spacer serves to prevent hot spots in moving applications with greater bending strain, as contact between the heating cables is avoided.
Eltherm Heated Hose DesignÂ
Eltherm’s controlled analytic heated hoses serve to transport gaseous media from the point of withdrawal to the analytic measuring device. In most cases they are fix mounted in plants or in the form of portable systems.
One of their primary functions is in officially mandated emission monitoring in power stations or waste incineration plants. Additionally the range of Eltherm analytic hoses are also increasingly used in process analytics by various industries including petrochemical, oil and gas.
Thorne & Derrick provide a complete portfolio of Electric Process & Trace Heating Solutions for Industrial, Hazardous Area & Explosive Atmospheres,
Specialist Distributors of Electrical Heating, Lighting, Power & Process Instrumentation Equipment to deliver significant safety and reliability improvements in the Industrial, Explosive Atmosphere & Energy sectors.
Your proactive problem solvers experienced in succession planning for the replacement of obsolete, non-conformant and legacy equipment in hazardous areas with ATEX & IECEx Certification & DSEAR Regulatory Compliance.
Industries Supplied | Process, Oil & Gas, Petrochemical, Utility (Water, Gas & Electricity), Food & Beverage, Pharmaceutical, Renewable, Rail, Datacentre, Battery Storage
Product Categories | Electric Heating | Lighting | Control Panels | Confined Space Safety | Plugs & Sockets | Isolators | Enclosures & Junction Boxes | Control Stations | Motor Starters Gas Detection | Security Access Control | Duct Seals | Cable Accessories LV HV | Earthing & Lightning Protection | Feeder Pillars | High Voltage Electrical Equipment | Joints Terminations Connectors MV HV
Published 13 Mar 2020
Press Release Date: 02.04.2020 uploaded by Chris Dodds (T&D Sales + Marketing Manager) World’s First Fully Certified ATEX Doors Thorne & Derrick International, the Experts in Equipment for Explosive Atmospheres, today announce the signing of a Commercial Distribution Agreement...
Published 04 Jul 2019
Press Release Date: 04.07.2019 uploaded by Chris Dodds (T&D Sales + Marketing Manager) Category: Stockist Distributor Agreement Announcement Thorne & Derrick International announce that they have signed a Preferred Distributor Agreement with Raytec, the world leading manufacturer of LED...
