PRESS RELEASE Exclusive contribution for CITplus, issue 03/2004 Subject: ATEX in bulk material handling Author: Gerhard Nied Technical Manager Company: AZO GmbH + Co. KG Industriegebiet Ost D- 74706 Osterburken Tel. 06291/92-0 Fax 06291/929 500 e-mail: info@azo.de Internet: http://www.azo.de Osterburken, 08.12.2004 nd-ns (CIT03_04.doc)
Page 2 of 7 ATEX in bulk material handling On 1st July 2003, an essentially changed legal situation became effective for all operations in which an explosive atmosphere can be caused by gases or dusts. A new, Europe-wide legal foundation for explosion protection was provided by two directives: (RL) ATEX 100a and ATEX 137. The European Directive 94/9/EG - also known as "ATEX 100a Product Directive" - governs those who produce or market products (devices etc) to be used in hazardous surroundings. Like the EC Machine Directive, ATEX 100a is directed at those who produce or market devices, components, protective, safety or control systems used in hazardous locations. For the first time, non-electrical equipment and protective systems are also included in ATEX 100a. Diagram 1 Photo 1 The European Directive 1999/92/EG - also known as ATEX 137 Operator Directive - governs the working safety to be ensured by operators of technical facilities. ATEX 137 is directed at operators of technical facilities; transferred into German law by working safety regulation (BetrSichV), it has been effective since 3rd October 2002. Many types of industry are affected by ATEX, e.g. food production, feed production, pharmaceutical and plastics processing. All combustible (and therefore organic) substances finely distributed in the air as a dust cloud are capable of reacting explosively with an ignition source. This applies to flour, coffee and cocoa as well as for wood, plastic and feed. Metal dusts such as aluminium and magnesium are also flammable therefore the regulations of dust explosion protection also apply to sections of the metal-working industry. Consequently, in hazardous areas only equipment which possesses a certification of CE conformity according to ATEX 100a is acceptable and is identified belonging to one of the defined categories.
Page 3 of 7 The equipment categories may only be used in zones which are defined accordingly (see Table 1): TABLE 1: ZONES AND CATEGORIES Zone An explosive atmosphere 20/0 is to be expected constantly, frequently and over longer periods of time 21/1 is to be expected occasionally 22/2 is not to be expected or only over short periods of time Category according to ATEX 100a Safe operation of equipment must be ensured 1 even with infrequent occurrences of equipment trouble 2 with equipment trouble to be expected 3 during normal operation Products subject to the ATEX 100a directive 1. Equipment Machines, equipment, devices, control and equipment parts, warning and preventive systems (e.g. mixers, mills, centrifuges, agitators, elevators, hoists, conveying screws, lamps etc) 2. Protective systems Devices that immediately stop incipient explosions and/or limit affected areas; are put separately on the market, generally with design inspection certificate (e.g. explosion-suppression systems, pressure relief devices, quick-lock valves etc) 3. Components Components required for safe operation; without autonomous function (e.g. pressure-proof housings, sensors, bearings, etc.) 4. Safety, monitoring and control systems Used outside explosion-protection areas, but important for safe operation of equipment and protective systems in explosion-protection areas (e.g. control centre for explosion-suppression system) How does the ATEX directive affect the machine directive? The machine directive loses its validity as a basic regulation for the subject matter covered by the 94/9/EG.
Page 4 of 7 For machines not subject to RL 94/9/EG (ATEX 100a), however, point 1.57 of the machinery directive does apply, which stipulates: The machine must be designed and constructed in order to avoid any risk of explosion posed by itself or by gases, liquids, dusts, vapours and other substances released or used by the machine. Therefore, the manufacturer must take appropriate measures to avoid hazardous concentration of the substances in question; avoid ignition of hazardous atmosphere; limit, if an explosion does occur in spite of this, the effects on the locality to a harmless degree. The same measures have to be taken if the machine is intended by the manufacturer to be used in an explosive atmosphere. Electric equipment belonging to such machines must be conform to specific directives concerning the danger of explosion. In production plants with bulk material handling, two areas constitute a typical connection between the applications of RL 94/9/EG and RL 1999/92/EG (in Germany BetrSichV). Pickup of product in bags In this area, feed hoppers are frequently used for manual product intake from bags. Case 1: A feeding hopper without ventilation (advisable only for bulk material with a slight tendency to develop dust). In this case, Zone 20 must be defined in the interior of the feed hopper. All around the intake opening, Zone 21 must be defined (usually 1 m radius around the opening, see EN 50281-3). Case 2: Photo 2 Much more frequently, feeding hoppers with dedusting filters and dust collectors are used. In this case, too, Zone 20 must be defined in the hopper interior and in the filter. Round about the feed opening, no dust will escape in normal operation, meaning that here Zone 22 is to be defined (usually 1 m radius around the opening, EN 50281-3). These definitions necessitate the use of equipment in the zones of corresponding categories according to RL 94/9/EG. In case 1, category 1D inside, category 2D within a 1-m radius outside around the opening. In above case 2, category 1D inside, but only category 3D within a 1-m radius around the opening outside.
Page 5 of 7 Safety screening is often done in the product intake area, using cyclone screeners. Due to the high circumferential speed, a potential ignition source exists in the screener interior and in Zone 20. Therefore a design inspection must be carried out by a "specified authority" before the machine will receive an identification in accordance with the directive. Photo 3 Identification according to ATEX 100a Identification is an important part telling whether ATEX 100a was applied. The directive outlines that the identification must consist of the CE sign and - in cases additionally requiring an EC design inspection - the ID number from the specified authority that has checked the QA system. In addition, the ID contains the characteristic hexagonal explosion-protection sign required by equipment for use in explosive atmospheres, in conjunction with information as to Group (e.g. II = above ground) and Category plus specification gas (G) and/or dusts (D).This identification is also required for components, with the exception that the CE sign must not be affixed. Example: An AZO screener for use in the vicinity of zone 22, i.e. category 3 (D = dust), which may have a maximum surface temperature of 135 C, is identified as follows (as described before, the interior of the screener is zone 20.).
Page 6 of 7 Discharge systems for BIG BAGs With the continuing trend to supply products in medium-sized packing units, systems for BIG BAG discharge are becoming increasingly popular. In this area, systems which operate with the BIG BAG connecting system have established themselves. With a double-ring locking element, this involves fitting the outlet spigot of the BIG BAG over a pipe, producing a dust-tight connection with a clamping lid. Only then will the BIG BAG be opened by untying the cord at the outlet. Normally by emptying BIG BAGs this way, dust will not usually escape, belongs in Zone 22. Dust leaks can occur particularly when the BIG BAG is emptied of product residue and compressed. There are measures to prevent this, such as evacuating the BIG BAG, ensuring it is totally empty and the air is completely removed. When BIG BAGs are used in bulk material handling, an occasional, brief escape of dust cannot be avoided. Therefore this is one of the critical points of operation within an automatic material handling system. Photo 4 Effects on manufacturer and system operator The two EU directives 94/9/EG and 1999/92/EG (ATEX 95 and 137) have been implemented nationally. The conversion process has caused manufacturers a great deal of cost and effort, especially in approved documentation and in certification of components and machines. Now the onus is on the system operators to establish zones for their existing and new machinery and to produce the required explosion protection documents in relation to safety regulations. Especially in dust areas, zones (Zone 21, Zone 22) organisational procedures should be dispensed by the system operator. Suitable measures are as follows: - Instruction of personnel - written instructions, work authorization and naming of persons responsible - Avoidance of ignition sources (smoking) - Cleaning measures to avoid hazardous dust deposits - Immediate removal of dust deposits caused by operational trouble In pharmaceutical production, for example, even Zone 22 can be avoided totally by the systematic cleaning after every batch or every shift (required anyway). Photo 5 In addition, it is necessary to identify a zone area at its entrances with the triangular W21 sign "Warning of explosive atmosphere".
Page 7 of 7 Correct zone definition can save costs and work in connection with CE conformity. Operators of automated material handling systems are challenged with many new requirements but competent manufacturers will be able to operate comfortably within the guidelines. Osterburken, 30 January 2004 nd-ns-bn (CIT03_04.doc)
Photos for CITplus, issue 03/2004 Photo 1 (AZ029712.tif) Product intake area for bags and BIG BAGs Photo 2 (AZ032010.tif) Feeding hopper without aspiration for lowdusting bulk materials Photo 3 (W440010.tif) Cyclone screener for safety screening below feeding hopper Photo 4(AZ031411.tif) BIG BAG discharge system Page 1 of 2
Photos for CITplus, issue 03/2004 Foto 5 (AZ036607.tif) Reconfiguration of external BIG BAGs into internal containers (pharmaceutical) Grafik 1(B003-03.bmp) Typical example of product process with bags and BIG BAGs Page 2 of 2