This spark doesn’t jump over

The flexible electrical heating systems from Winkler AG must work safely and reliably even in potentially explosive environments. The company therefore uses explosion-proof polyester housings from ROSE Systemtechnik as connection boxes. They are delivered ready-made.
For 40 years, Winkler AG has been developing and manufacturing a broad portfolio of trace heating solutions for customers from a wide variety of industries. The heating systems not only enable the transport of liquid or viscous media over long distances without loss of temperature. They also ensure that reactors, columns or barrels are always kept at an optimal temperature. Many of the Heidelberg company’s customers come from the chemical and pharmaceutical industries, which have special safety requirements: Systems that are used here often have to be protected against dust and gas explosions.

This not only applies to the heating systems themselves, but also to the junction boxes through which they are connected to the customer’s supply network. These housings must be constructed in such a way that sparks and hot surfaces do not arise in the first place. In addition, electrostatic discharges must not occur on the surface of the housing (TRGS 727 [15]), because they also lead to explosions in environments with high dust or gas concentrations.

Polyester enclosures from ROSE meet all standards

In order to meet these requirements, Winkler has been using explosion-proof polyester housings from ROSE Systemtechnik as junction boxes for its heating systems for over 20 years. Frank Merkel, head of product management for EX heating solutions and explosion protection officer at Winkler, not only appreciates their robustness: “We can always rely on the housings to comply with current standards. That is not a matter of course in the industry.”

The standard conformity of the housing plays a major role in the certification of the explosion-proof heating systems. Since 2007, Winkler has not only had its individual parts certified by the TÜV, but also the respective overall system, e.g. heating conductors, connection technology, connection boxes and sensors. The customer thus receives a single type examination certificate and can use the heating system immediately. Winkler introduced this service in 2007 as the first provider of flexible explosion-proof heating solutions in the industry. If the ROSE enclosures did not meet the current standards, Winkler would not be able to offer its “system certification” in this form.

Module certification reduces certification effort

The customers really appreciate this extensive service from Winkler. Before they were introduced, the company had to hand them over a mountain of documentation – a separate certification for each individual component. “Hardly anyone looked through it,” recalls Frank Merkel. The reason lies in the complexity of the topic and the lack of human resources in many companies. Smaller companies in particular often only deal with the topic of explosion protection when it becomes acute and therefore do not know exactly how such certification processes work. Winkler would like to relieve them: “We create clarity with our assembly certification and help customers to reduce their time and costs.”

Enclosure dissipate charges safely and quickly

The company mostly uses explosion-proof polyester housings from ROSE for the junction boxes of its heating systems, but in “normal” applications there are also stainless steel or aluminium die-cast housings. Winkler installs the explosion-proof polyester enclosures in two versions: as Ex i and Ex e enclosures. Both are made of a glass fiber reinforced thermosetting polyester and contain a graphite additive. It ensures that electrostatic charges are quickly and safely discharged before they could ignite any potentially explosive atmosphere.

Winkler installs the controller sensor and the limiter sensor for its heating systems in the Ex i polyester housings from ROSE. These enclosures are intrinsically safe, i.e. the requirements are not quite as strict as those for enclosures with other types of protection. Ex i devices must be designed in such a way that they limit the energy that is conducted from them into the potentially explosive area. This means that the electrical energy of a spark that occurs inside the housing must always be less than the minimum ignition energy of the surrounding explosive atmosphere. “Minimum ignition energy” means the energy that is sufficient to ignite the “most ignitable” mixture in an explosive atmosphere and thus cause it to explode.

Special solutions are not a problem

ROSE equips the Ex i polyester housing for Winkler with terminal blocks, screw connections and cable screw connections. All explosion-proof polyester enclosures are available in sizes 75 x 80 x 55 mm to 405 x 400 x 120 mm and can be used in temperature ranges from -55 to +135 ° C. “But there are also junction boxes that we modify to customer specifications,” reports Frank Merkel. “I usually send ROSE a little sketch of how we want it to be, and then we get a special solution.”

The connection boxes for the power supply of the heating systems have to meet somewhat higher requirements for explosion protection. For this reason, Winkler uses polyester enclosures with type of protection Ex e. These housings do not accept temperatures that are above the temperature class of gases that can occur at the place of use. This should prevent any potentially explosive atmospheres from igniting. In addition, there are no sparks or arcs on or in these housings, which could ignite an explosive atmosphere.

Pre-assembled and ready to use

In addition to explosion-proof enclosures made of polyester, ROSE also produces versions made of stainless steel and aluminium, which are particularly suitable for use in harsh environments (e.g. offshore). In addition, explosion-proof control stations are available with which systems can be controlled directly on site. All housings are approved for use in ATEX zones 1 and 2 (gas explosion protection) and in zones 21 and 22 (dust explosion protection). Most of the housings are delivered fully assembled, i.e. in other words, they are already equipped with all the necessary electronic components and connections. In the ex-protected models, ROSE installs special ex-tested terminals and cable glands in order to avoid any spark. Since the paint used for painting the housing contains plastic that cannot dissipate an electrical charge, the thickness of the paint layer is also limited (max. 0.2 mm).

Top quality, fast service

Frank Merkel is very satisfied with the housings and the service from ROSE: “The products are absolutely top-notch, we only had one complaint in 20 years. And if we need a special solution, we are always given quick and competent help,” says the happy product manager who looks after the area of flexible, explosion-proof heating solutions.