Over the years, any industrial plant will face wear and tear on individual pieces of equipment. This includes distribution boards designed for use in potentially explosive atmospheres. Few businesses are aware that replacing distribution boards can be a good way to make savings in the short and long term.
The problem of becoming set in your ways
Most tasks in production plants are carried out based on procedures in order to ensure that the process is repeatable and yields products of the same quality. However, when an installation needs to be restored, e.g. after a failure or due to wear and tear of the equipment, businesses often act in a habitual manner that they became accustomed to over the years. As a result, rather than look for solutions that are optimal as of the date of their purchase, businesses prefer vendors that will provide them with the same solution that they have been using for years.
This behaviour stems from becoming accustomed to the devices used by the company, even if they pose certain problems. This is because the concept of ‘getting used to equipment’ also applies to expertise in dealing with problems related to the equipment, obtained with the passage of time. Over this period, users simply learn how to perform specific maintenance and repair jobs
How does ‘habituation’ lead to considerable costs when it comes to distribution boards?
Distribution boards in type Ex d flameproof enclosures are used today in many manufacturing plants. This type of enclosure will allow for an explosion to occur inside the enclosure, but will prevent it from reaching the outside environment. Due to this, regular electrical components, i.e. non-ATEX certified, can be installed inside these enclosures. These units are generally less expensive than certified units, which is often the main reason for choosing this type of enclosure.
However, in order for this type of enclosure to offer effective protection against the ignition of the explosive atmosphere around it, great care must be taken during its operation. Particular attention must be paid to the condition of the quenching gap. Even a tiny scratch, caused for example by a screwdriver, can be extremely dangerous, as shown on the video below.
However, this solution is expensive in everyday operation. Its costs result from factors such as the considerable price of type Ex d flameproof enclosures; the reduced cost of using non-certified, less expensive components is usually insufficient to make up for it. A second cost-increasing factor is the need for meticulous and frequent inspections of the quenching gap in order to detect any signs of wear early enough.
Searching for an optimal solution can lead to savings
The aforementioned difficulties in the operation and maintenance of distribution panels inside type Ex d flameproof enclosures are very often not taken into account when replacing the panel, because everyone has become accustomed to using them. When searching for an optimal solution, it’s therefore a good idea to make an argument based on costs.
Let us consider how different things would be if a manufacturing plant decided to install distribution panels inside type Ex e reinforced enclosures. All components of the panel would be more expensive in this case, as they need to be ATEX certified. However, a closer look at the issue shows that this is the only factor associated with increased costs when compared to using distribution panels inside type Ex d flameproof enclosures. On the other hand, the following costs can be reduced:
▶ cost of purchase, as type Ex e reinforced enclosures are several percent cheaper than type Ex d enclosures
▶ cost of installing the enclosure, as it is much simpler and, therefore, less expensive. Type Ex e enclosures are light, as they are usually made of plastic or thin metal sheet. Type Ex d enclosures, on the other hand, are much heavier and bulkier, as their structure must withstand internal explosions, meaning that advanced equipment and tools must often be used in their installation
▶ cost of labour of maintenance staff during maintenance works, as distribution panels inside type Ex e enclosures do not require thorough inspections of their quenching gaps
▶ costs are also reduced thanks to the fact that distribution panels inside this type of enclosure can be sooner brought back online after an overload thanks to special inspection openings, which cannot be used in flameproof enclosures.
Photo: Inside view of an explosion-proof switchgear (in type Ex e enclosure) during prefabrication at a WOLFF GROUP plant.
Summary
There is an old Polish saying that ‘the best is the enemy of the good’. Although true in many areas of life, in this case it falls wide of the mark. Habituation to the ‘good’ over the course of many years becomes detrimental to seeking a better and cheaper solution, even when the ‘good’ may in fact be poor, but is chosen simply because it’s a known quantity.
This article is based on an actual project implemented by WOLFF GROUP’s engineers for a leading Polish chemical manufacturer. It aims to showcase a recommended method of approaching the process of replacing devices and restoring installations inside EX zones.
Powyższy artykuł został oparty na rzeczywistym projekcie zrealizowanym przez inżynierów GRUPY WOLFF dla jednego z wiodących producentów chemii w Polsce. Jego celem jest pokazanie, w jaki sposób warto podejść do procesu wymiany urządzeń i odtworzenia instalacji w strefach EX.
