Assessing the combustible properties of collected substances: An important consideration when choosing a vacuum cleaner
Tiger-Vac Inc.
Leading manufacturer of industrial vacuum cleaners for contamination of controlled environments & hazardous locations.
Using a vacuum cleaner to collect combustible substances in an explosive atmosphere is a hazardous operation.
Standard EN 17348[1] establishes that ignition hazards are not only associated with the vacuum cleaner but also with the type of substance collected.
Based on the best practices of safety standards relevant to explosive atmospheres, EN 17348 guides manufacturers in designing vacuum cleaners for the safe collection of combustible substances and helps users choose the right equipment for their specific work environment and application.
When considering a vacuum cleaner for collecting combustible substances, users must know the combustible properties of their substances or mix of substances:
For flammable liquids, users must know the flash point[2] of the liquid and auto ignition temperature (AIT)[3] to ensure that the vacuum’s maximum surface temperature doesn’t act as a source of ignition. Knowing the Gas Groups[4] of the substances present in the working area is very important, as the marking on the vacuum cleaner specifies the flammable substances that the equipment is designed to be used with.
For combustible dusts or mixtures of combustible dusts, the user must perform a dust hazard analysis to determine the Minimum Ignition Energy (MIE)[5] and the minimum ignition temperature (MIT)[6] of the dust or mixture of dusts.
By reviewing the dusts’ combustible characteristics, the maximum surface temperature of both the external and internal parts of the vacuum cleaner used with the dusts, and the maximum energy that can be produced while using the equipment, users can evaluate if the vacuum cleaner is designed to safely collect the combustible dust.
For self-heating dusts, users must use a Wet Type dust collector. This vacuum is designed to submerge the collected dust into a liquid bath to neutralise its combustible properties.
Standard EN 17348 helps users choose the appropriate vacuum cleaner based on the combustible properties of the substances to be collected.
Standard EN 17348 defines three types of collectors:
·??????? Dry Type dust collectors designed to collect combustible dusts
·??????? Wet Type dust collectors designed to collect self-heating dusts
·??????? Liquid collectors designed to collect flammable liquids
EN 17348 requires manufacturers to specify the type of collector on the vacuum’s nameplate for the operator’s reference.
EN 17348 is the only standard harmonised under ATEX Directive 2014/34/EU regulating the specific application of combustible substances collection. As such,?compliance of vacuum cleaners with EN 17348 is imperative to ensuring safety when collecting combustible substances in explosive atmospheres. This is why an ATEX certification not covering compliance with EN 17348 is not enough to ensure that a vacuum cleaner is safe for the collection of combustible substances.
?
[1] EN 17348: 2022,?Requirements for design and testing of vacuum cleaners for use in potentially explosive atmospheres, has been harmonised under?ATEX Directive 2014/34/EU?on March 17, 2023. EN 17348 applies to?both electrical and non-electrical Category 2 and Category 3 vacuum cleaners, for dust or liquid collection in both gas and dust explosive atmospheres.
[2] The flash point is the lowest liquid temperature at which, under specified test conditions, a liquid gives off vapours in quantity such as to be capable of forming an ignitable vapour-air mixture (IEV ref 426-02-14).
[3] The auto ignition temperature (AIT) is the lowest temperature (of a hot surface) at which, under specified conditions, an ignition of a flammable gas or vapour in mixture with air/inert gas occurs (IEV ref 426-02-01).
[4] Equipment certified for use in presence of flammable gases are divided in different Groups and subgroups depending on their safety properties and the flammability characteristics of the gases.
[5] The Minimum Ignition Energy (MIE) is the minimum energy that can ignite a mixture of a specified flammable material with air, measured by a standard procedure (IEV ref 426-02-38).
[6] The minimum ignition temperature (MIT) is the lowest temperature of the hot surface on which the most ignitable mixture of dust with air is ignited under specified test conditions or at which ignition occurs in a dust layer under specified test conditions (IEV ref 426-02-20/21).