The risks of ignition from workplace transport and plant equipment
24 February 2017
A lift truck, crane or other workplace transport will have multiple sources of ignition, whether from heat, static or arcing and sparking components. Rob Vesty of Pyroban looks at the latest standard EN1755:2015 and explains how the most complex mobile equipment can be converted to achieve ATEX compliance in Zone 2 areas.
For forklift trucks and warehouse equipment such as cleaning machines, counterbalance trucks, pallet trucks, VNA and reach trucks, the market typically chooses to convert existing models to gain maximum efficiency from the very latest technology. Similarly, for cranes, access platforms and other mobile equipment, there isn’t the volume for an EX manufacturer to build a complete ATEX unit.
Users will therefore tend to request a conversion from their local equipment supplier. With the lift height, dimensions and all associated specifics defined to get the job done (i.e. moving pallets or maintaining lighting in a distillery). There are then three key areas that suppliers and users should be aware of.
Compliance with ATEX 2014/34/EU is the most obvious, alongside European Standard EN1755 , which governs companies involved in the manufacture or conversion of industrial trucks to enable safe and compliant use in hazardous areas. A recent update took place to clarify and standardise the required safety measures.
The new EN1755:2015 standard for explosion protected forklifts is mandatory from November 2017. The update to “Safety of industrial trucks. Operation in potentially explosive atmospheres. Use in flammable gas, vapour, mist and dust”, brings together the latest market knowledge and solutions, and references the latest standards which were not available when first issued in May 2000.
EN1755:2015 clarifies and standardises the level of safety required for products on the market. Requirements concerning static electricity will have a significant impact on trucks built or converted for Zone 2 operation (3G) from both an end user and maintenance perspective.
A spark from unprotected electrical equipment on a forklift, excess heat from the engine, motors, brakes and other components, or even a spark from static build up, can create enough energy to cause ignition.
In EN1755:2015, static electricity will be considered an ignition risk during “normal” operation. Therefore, seats, arm rests, roll up cabin sides and other externally accessible plastics need to be antistatic as a minimum. All tyres (where travel speeds are >6km/h) on 3G trucks should also be antistatic and there must be conductivity to earth either with two straps from the chassis to ground or by using conductive tyres. The location and quantity of conductive tyres or earthing straps should also be marked on the chassis.
For Zone 2 applications, the new EN1755:2015 requirements have maintained the core principles of the current standard and brought them into line with relevant latest legislation. Gas detection is core to 3G protection, but performance requirements are strengthened to achieve Performance Level PLc (EN13849) or SIL 1. Testing has also been redefined for Ex nR restricted breathing enclosures which require stronger leak performance. Truck labelling has also been redefined and handbook requirements are more detailed.
Changes that affect all categories of equipment (2G, 3G, 2D and 3D) include more detailed assessment of non-electrical components such as pumps and transmissions in line with EN13463. Safety control systems should also meet EN13849 or SIL 1.
For load handling devices, such as forks or clamps, the areas requiring cladding are redefined and brass, not stainless steel, should be used where the flammable material is in the IIC gas group.
Another standard affecting truck conversions is ISO 3691-1:2011, the international standard for safety requirements and verification of industrial trucks, such as forklifts. It guides best practice for modifying forklifts with safety in mind, including explosion protection conversions.
Under this standard, truck modification is not permitted without prior written approval of the original equipment manufacturer to ensure that all potential implications which may affect the overall truck safety have been considered. So, in the case of explosion protection, even if a modified truck meets the requirements of the ATEX Directive, it may not comply with ISO 3691-1:2011 unless written manufacturer consent has been obtained.
Selecting the Best System for Zone 2 Mobile Equipment
Faced with operating a forklift truck, or other mobile equipment, within a potentially explosive environment, a company must select the right explosion proof solution for their needs. If the wrong gas detection technology is used, it impacts the effectiveness of the complete safety system and a truck user could be rendered ‘blind’ to the presence of a flammable atmosphere, jeopardising the safety of the site and putting themselves and their colleagues at risk.
Assuming a company has correctly established a ‘Zone 2' area, Pyroban’s most popular system for mobile equipment is system6000™ which incorporates g
Gas detection systems are use Pellistor or infra-red technology.
Pellistor based systems: Those with a working area at risk due to handling a wide range of different potentially flammable products, such as companies handling chemicals or those in the paints/coatings industry, should usually select a pellistor based detection system, although they may not be suitable if silicones are present in the atmosphere.
Systems with infrared sensors: Operations with single or far fewer hazard types often find infrared technology is most suitable. Many distilleries, cosmetics producers and warehouses handling aerosols successfully use this option. LPG cylinder filling operations or LPG distribution centres would also be better suited to an infrared detection system.
Alongside gas detection systems, vehicles should use explosion protection methods such as restricted breathing enclosures, stainless steel cladding of forks and surface temperature cooling to ensure the engine, motors, brakes, electrics and other components remain below the auto-ignition temperatures of flammable materials.
To ensure that the operator is instantly informed when gas is detected, the control module for the system should be located within easy reach and view of the operator. Auto-calibration functions which remove the need for periodic and costly site visits by engineers having to recalibrate the gas detection are also useful.
Case study: Explosion proof forklifts for ADPO chemical warehouses
Chemical logistics business ADPO acquired a new generation of explosion proof forklift trucks for its Antwerp operations. Toyota forklift trucks were converted by Pyroban for use in Zone 2 hazardous areas.
“Safety is the number one priority across our three sites in Antwerp,” says Karel Stoop, responsible for Antwerp Distribution and Products Operations’ (ADPO) mobile equipment. “With such significant volumes of flammable material being stored and handled, we operate with the highest environmental, safety and health regulations without compromise, which is why we use Pyroban explosion protected forklifts.”
ADPO’s main facility, on the left bank of the river Scheldt, is a 35ha integrated liquid bulk terminal where the company provides container logistics, tank storage, warehousing and drumming services.
At the terminal, ADPO operates 24,500m² of chemical warehousing in combination with five filling stations for drums and IBCs with a capacity of 400 tonnes per day.
“For more than ten years we have worked with Pyroban to ensure that the forklift trucks used in our Zone 2 areas cannot be the source of an ignition,” explains Karel. The trucks are used to transport and store IBCs and palletised drums both inside and outside, load and unload containers, and load conveyor belts in Zone 2 areas.
The trucks are handling many different flammable chemicals in sealed containers, so a flammable atmosphere is not expected unless by accident. However, each solvent or chemical liquid has a different characteristic so Pyroban made sure the protection covers all potential flashpoints and temperature classes.
The two new Toyota FDF30 forklift trucks were converted by Pyroban with full CE approval in accordance with the ATEX Directive and EN 1755 standard. There is also written consent from Toyota in line with ISO 3691-1:2011.
The new trucks feature Pyroban’s system6000D, which prevents explosions by combining gas detection with various explosion protection methods. The pellistor based gas detection system detects the wide range of potential hazards found in the chemical warehouse at ADPO. It auto-calibrates and self-tests at start up to ensure it is working correctly and the whole solution is certified with gas groups IIA and IIB.
ADPO operates a total forklift fleet of more than 60 machines across the three sites, many of which feature explosion protection from Pyroban. Shifts run from 6am to 5pm and each driver is assigned their own truck.
The trucks are regularly maintained by ADPO engineers at the well-equipped garage onsite with parts support from Toyota and Pyroban. The team of ADPO engineers is fully trained by Toyota and Pyroban and every three months the trucks are checked independently.
Furthermore, every year specialist Pyroban engineers conduct a thorough safety audit known as the EX-ASA.
“The EX-ASA ensures that the integrity and safety of the trucks is not compromised and gives us confidence that we are maintaining the equipment to the highest order,” says Karel.
All safety critical components of Pyroban’s explosion protection system are inspected and recorded, including Exd enclosures, cables and glands, shutdown devices, conductivity and fork cladding. Irregularities are repaired immediately and a certificate issued.
About the author
Rob Vesty is UK Sales Manager for Pyroban and has worked for the company for 16 years. Working with various materials handling solution providers, his role includes end user support to ensure that the correct explosion protection specification is provided for equipment working in formally classified areas under the ATEX 2014/34/EU Directive.
Past roles have included key account management with a responsibility for both service and service engineers, as well as sales and technical support to materials handling customers and end users in a wide range of different industries.
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