Idler Roller Aluminium Idler Roller offer Light Weight, Safety, and Protection
Extensive testing at the RWE Tilbury Power Station and three years of operationat E-ON’s Kingsnorth Power Station proved that aluminium rollers are a lightweight alternative to steel that are safer to use in hazardous Atex environments.
Four years ago Horizon Conveyor Equipment launched an innovative range of aluminium rollers that have gone on to be tested in demanding conveyor installations all over the world. But while site operators have been quick to embrace the major health and safety advantages of using these lightweight rollers, their unique design is also providing an altogether new solution to a potentially explosive problem.
In hostile locations where conveyor reliability and the risk of fire are critical concerns, Horizon’s tightly sealed aluminium rollers are proving to be a superior option. Specially designed to operate at stable temperatures and cut the risk of electrostatic charges, the rollers are not only lighter but also safer than conventional steel rollers in Atex environments where any excess heat, sparks or fire could have catastrophic consequences.
Horizon originally developed aluminium rollers in response to industry concerns about the health and safety risks of using standard heavy steel trough and return rollers. Often weighing up to 90 kg, steel rollers can require extra manpower and prolonged downtime to fit and replace safely, particularly in high or enclosed spaces. Increasingly stringent health and safety rules mean that operators also have to carefully consider the risks posed to personnel from steel rollers during regular conveyor running.
Alan Bowler, the Managing Director of Horizon Conveyor Equipment, says the aluminium rollers retain the durability of their steel counterparts but boast the weight advantages, noise reduction and energy saving features that have made plastic rollers popular. Importantly, their high strength also makes them an ideal option for use on wide belts and in high impact locations.
He said: “Our aluminium roller has all the weight and handling advantages of our HDPE plastic rollers but with the added advantage of extra strength especially for long return rollers. This is absolutely critical for operators who face real health and safety issues when attempting to replace failed steel rollers.”
Light and Strong
Designed using 6 mm thick aluminium tube, the rollers contain a steel shaft and sealed bearings, with the bearing housings manufactured from electrically-conductive glass-reinforced nylon. A large stationary integral stone guard forms the outer primary labyrinth seal, which prevents any spillage building up between the roller and the frame which can jam the roller. Dust, debris and smaller contaminants are kept out by a greased inner cupped lip seal together with a sealed bearing.
For the past three years the rollers have been in use at E-ON’s Kingsnorth Power Station, mainly on 1350 mm and 1800 mm belts. Clive Burfoot, Materials Handling Engineer for E-ON at Kingsnorth Power Station, says the weight of the rollers has been a major benefit on site.
“We have tested Horizon Conveyors’ aluminium rollers for more than three years and have been very pleased with their performance,” he said. “We decided to install them into a position of high tension, close to the pulley tail, to accelerate the tests and they have performed very well.”
While the aluminium rollers offer immediate weight gains to site operators, their unique construction delivers superior performance and longevity in high risk environments. With heavy duty seals and sealed bearings, the rollers offer greater resilience in areas where fine dust from the likes of biomass pellets, wheat, sugar, flour and cement can be hugely damaging to standard rollers.
Following its conversion from coal-power to biomass, RWE Tilbury Power Station began trialling the aluminium rollers after finding that its existing steel rollers were failing at an alarming rate.
Ron Pannell, Lead Maintenance Engineer at RWE Tilbury Power Station, said that after careful monitoring the existing equipment and investigation it was found that extremely fine biomass dust was getting through the seals of the steel rollers and into their open cage bearings. “Once any dust ingresses the seals and bearings, the rollers were generating excessive heat and that is a real problem with biomass dust,” he said.
RWE set out to find a solution that would reduce the risk of fire created through excess heat and roller failure but would also be light weight for easy installation. Horizon’s aluminium roller was chosen for its robust labyrinth and bearing lip seals and because of its electrically conductive bearing housing, which cuts the risk of sparks and prevents metal to metal bearing contact in case the roller should ever fail.
RWE’s team at Tilbury put Horizon’s aluminium rollers through an extensive trial, which involved running them for a period and then opening the seals. It found that there hadn’t been any ingress of biomass dust through the seals or into the sealed bearings.
For Alan Bowler at Horizon, the introduction of the aluminium roller range marks the latest development in nearly 30 years of research and design innovation. He was originally involved in the invention and patenting of the first non-metallic plastic-polyurethane rollers which were introduced into the South African market in 1980. He brought the designs to the UK and European market in 1995 and since then has established a range of steel, plastic and now aluminium rollers.
He said: “We originally conceived the design for the aluminium roller with health and safety in mind. With tighter regulations and more consideration to the manpower and downtime needed to change failed steel rollers, there is certainly a need for a lightweight alternative. But the way we have constructed these rollers means they are also capable of solving a wide variety of problems and reducing risks in some very hostile Atex environments.”