KANBrief 3/25
Mobile machinery is often used in environments contaminated with hazardous substances and biological agents. To protect the operating personnel, a number of machinery standards set out requirements for the design and ventilation of enclosed operator’s cabins. The level of protection specified differs, however, from machine to machine. OSH stakeholders take the view that a harmonized reference should be created.
Operator’s cabins, and requirements concerning their ventilation for protection against biological agents and hazardous substances, are addressed in numerous standards for mobile machinery. Design requirements are often formulated in a section of a product standard (e.g. for industrial trucks, earth-moving machinery or forestry machinery). Some standards are also devoted exclusively to the ventilation of a specific type of mobile machine (e.g. mining machinery or tractors).
The corresponding standardization activity is conducted in a number of standards committees, and the groups of experts involved are often working in isolation. The OSH stakeholders therefore consider it appropriate to analyse what requirements for the ventilation of operator’s cabins can be formulated in a horizontal standard applicable to all types of machinery, so that the operating personnel enjoy the same level of protection against biological agents and hazardous substances. Each standards committee affected could then refer to the requirements of the horizontal standard, or where necessary adapt them to the respective mobile machine.
In 2023, KAN tasked DIN Software with conducting a survey analysis identifying all standards in which operator’s cabins are addressed and in which their ventilation, and thus their protection against hazardous substances and biological agents, are relevant. The scope of the analysis did not include requirements concerning the cabin climate or ergonomics. In a follow-up project, a team led by Dr Günther Weise from the German Center for Forest Work and Technology (KWF) evaluated the full texts of the relevant documents. The aim was to identify ventilation requirements that could be viewed as generic: for intended use on the one hand in environments contaminated with hazardous substances and biological agents, and on the other in uncontaminated areas. The results were to be incorporated into a document serving as a basis for the draft of a horizontal standard (type B standard).
Following identification of relevant documents, they were reviewed and relevant ventilation requirements categorized, enabling those that could be considered generic to be identified systematically. Of the standards examined, documents from the field of construction machinery were the most numerous, followed by those for agricultural machinery, industrial trucks, railway technology, mining machinery and forestry technology. Many of these standards also explicitly formulate requirements for cabin ventilation when the machinery is used in contaminated areas.
To enable the standards to be evaluated, a list of keywords was compiled that reflect the relevant aspects of ventilation technology (see Figure). With reference to the frequency and content of the corresponding references in standards, a more detailed analysis was performed of which requirements are relevant for a horizontal standard. According to the analysis, the main hazards associated with the operation of mobile machinery are dusts (usually of mineral origin, but possibly also of biological origin, such as wood dust). These are neither toxic nor infectious; their harmful effect arises from their physical properties.
The standards examined are unanimous in requiring a closed operator’s cabin for use cases involving hazards due to dust exposure. The cabin must feature a supply air inlet with a filter insert, possibly even with a prefilter, and a ventilation element including an exhaust outlet. Suitable filters, for example to EN 1822-1, High efficiency air filters (EPA, HEPA and ULPA) – Part 1: Classification, performance testing, marking, must be used. The system as a whole must ensure a positive pressure in the cabin. In addition to the requirements concerning filters, analysis of the standards also identified requirements for design of the air ducting and pressure tightness. This can be regarded as the basic level of protection for operators against dust.
Where the air is contaminated by hazardous substances with toxic effects or biological agents with infectious and sensitizing effects, the working environment is deemed to be contaminated. In such cases, the ventilation system of the operator’s cabin must satisfy requirements extending beyond those for the basic level of protection, in order to assure effective protection against contamination. Examples of these requirements are controlled positive pressure atmospheres, compressed air breathing systems and suitable filter components. A horizontal standard should also provide information on other aspects to be considered when hazards are presented by gases and vapours (e.g. special gas filters).
The project resulted in the preliminary text of a draft standard, entitled: Self-propelled machinery – Ventilation systems for enclosed cabins – General requirements for protection against hazardous substances and biological agents. This document proposes common basic requirements to be met by ventilation systems in the enclosed cabins of self-propelled and mobile machinery, tractors and industrial trucks.
The draft defines two categories of cabin for different working environments. The first category includes basic protection against general exposure to dust. The second category provides additional protection against hazardous substances and biological agents. By modifications to the ventilation system, cabins in this category can also be adapted to provide protection against hazardous gases. A very important aspect of this draft standard is that the requirements also apply to retrofit solutions, an approach taken by many manufacturers and users. KAN will now submit this document to the responsible committee at DIN with the aim of presenting it as a proposal for a standard at European or international level.
Dr.-Ing. Günther Weise
German Center for Forest Work and Technology, KWF
guenther.weise@kwf-online.de
Dr. Anja Vomberg
vomberg@kan.de
