AREA CLASSIFICATION – ZONING. EN / IP Zone 0: The part of a hazardous area in which a flammable atmosphere is continuously present or. Figure Hazardous area zone classification shading convention. .. referred to as IP15) is a well-established Model Code for area classification in the. Level Definition In Hazardous Area Classification Ip15 – posted in Industrial Professionals: Hello, All For those who are familiar with hazardous.

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The different parts of this standard set out requirements for construction of equipment for use in atmospheres containing explosive dusts; information about selection and maintenance; and BS EN The flammable materials that may be present; The physical properties and characteristics of each of the flammable materials; The source of potential releases and how they can form explosive atmospheres; Prevailing operating temperatures ipp15 pressures; Presence, degree and availability of ventilation forced and natural ; Dispersion of released vapours to below flammable limits; The probability of cclassification release scenario.

Appendix 2 describes the requirements for hazardous area classification. Existing plant will not meet the formula in DSEAR, but older standards distinguished between electrical equipment suitable for zones 0, 1 and 2.

The alternative of specifying the extent of zones more conservatively is not generally recommended, as it leads to more difficulties with equipment selection, and illogicalities in respect of control over health effects from vapours assumed to be present. These, the standard current in midand the letter giving the type of protection are listed below. The Dangerous Substances and Explosive Atmospheres Regulations DSEAR provide for the first time a specific legal requirement to carry out a hazardous area study, and document the conclusions, in the form of zones.

These should now be seen as rather conservative. At present these are sold without any claim for ATEX compliance, but with the suggestion they may be useful in cases classsification remote risk. Instead, a more realistic assessment of the zones is needed, and special instructions issued for the rare event of using more volatile fuels.

API versus IP15 – IET Engineering Communities

Safe systems of work are needed to ensure safety where such ‘transient’ zones exist. An area in which an explosive gas atmosphere is present continuously or for long periods; Zone 1: The guidance also recommends that zones be recorded in a plan to prevent sources of ignition being brought in.


This Technical Measures Document refers to the classification of classifivation into hazardous areas, and the systematic identification and control of ignition sources. If this is possible, it is more appropriate to provide controls to prevent the spread, rather than simply apply more conservative zoning, and more restrictive rules on the equipment used in the store.

Consequently, many employers are likely to try and justify not zoning storage compounds, where lift trucks handle flammable liquids or gases in containers.

The IGE code addresses specifically transmission, distribution and storage facilities for natural gas, rather than gas utilisation plant, but some of the information will be relevant to larger scale users. It contains a simplistic calculation relating the size of zone to a rate of release of gas or vapour, but it is not helpful for liquid releases, where the rate of vaporisation controls the size of the hazardous area.

Measures to prevent major accidents should address all potential initiators. Dust Explosion Prevention and Protection: This gives additional general advice on the many of the issues covered in this TMD.

Hazardous Area Classification and Control of Ignition Sources

Where toxic dusts are handled, in most cases occupiers will need to carry out testing of the product for its explosion properties. Non-electrical equipment The first standard for explosion protected non-electrical equipment is BS EN part 1 1.

However, for many jp15 we have used a small-scale screening test, the vertical tube test, described in HSG 2. The tables of dispersion distances to the zone boundary address in the main quite large diameter deliberate vents.

Level Definition In Hazardous Area Classification Ip15

For COMAH sites with toxic dusts, the most likely hazard would arise in drying processes, if substantial quantities were held for extended periods hot enough to start self heating or smouldering combustion. Skip to content Skip to navigation. Section 9 provides guidance on lightning protection of structures with inherent explosive risks. Vehicles certified to ATEX requirements are however expensive, and for many applications an unprotected type has to be extensively rebuilt.

This cross references BS EN Many sites will have operations of filling and emptying road tankers with flammable materials. Typically these will involve written instructions, as specified in DSEAR schedule 1, or a formal permit to work system. For most chemical products it is preferable to test dust taken from the process, but if the particle size distribution varies, it is common to test material that passes a micron sieve, and take this as the worst case.


Zoning Classifucation areas are defined in DSEAR as “any place in which an explosive atmosphere may occur in quantities such as to require special precautions to protect the safety of workers”. Other processes such as hot oil classfiication circuits may handle products above their auto-ignition temperature.

Catastrophic failures, such as vessel or line rupture are not considered by an area classification study. These factors enable appropriate selection of zone type and zone extent, and also of equipment.

The IP code gives a methodology for estimating release rates from small diameter holes with pressurised sources, and shows how both the buoyancy and momentum of the release influence the extent of a zone.

The relevant Level 2 Criteria are 5. Have appropriate standards been used for selection of equipment in hazardous areas? There is no legally defined test for an explosible dust. Further guidance can be hazadous in BS Vehicles Most normal vehicles contain a wide range of ignition sources.

The starting cpassification is to identify sources of release of flammable gas or vapour. The standards detailing selection of appropriate electrical apparatus have been updated clzssification take into consideration ventilation effects. The results of this work should be documented in Hazardous Area Classification data sheets, supported by appropriate reference drawings showing the extent of the zones around including above and below where appropriate the plant item.

A dust explosion could then be an initiator of a major accident. Has ignition protected electrical equipment been installed and maintained by suitably trained staff. Locations where a large release is possible and the extent of hazardous areas has been minimised by the use of mechanical ventilation should be identified, e. For the purposes of COMAH, an assessment is needed of the risk that an ignition within a storage compound will produce a major accident, either directly or because a fire or explosion spreads to involve other materials.

Discussions have been held with the British Chemical Distributors and Traders Association, with the objective of clarifying when storage areas should be classified as zone 2. Sources of ignition should be effectively controlled in all hazardous areas by a combination of design measures, and systems of work:.