Since 1973, filtration and safety equipment supplier John Ratcliffe has focused on providing clients with a range of quality filtration, exhaust and safety equipment. Some of these products will be exhibited at this year’s Electra Mining Africa trade show and include the HJS sintered-metal diesel- particulate filtration units and catalytic converters, as well as flameproof thermal camera systems.

John Ratcliffe GM Andre Robberts says the German-manufactured HJS systems are custom made and installed to client specifications and requirements. “The sintered metal filter (SMF) is a system that sets new standards in the global marketplace. This closed, 100-micron filter reduces the emissions of soot particles, including fine-particulate matter, down to the lowest limits of detection with a filter efficiency of more than 99%,” he says.

The SMF and other systems based on it are reliable, low maintenance and offer a long service life. The pocket-type construction of the SMF prevents clogging more effectively than conventional ceramic filters, which are traditionally designed with a honeycomb structure.

The construction significantly increases the hours of use, depending on the engine type and operating profile of the vehicle, before stubborn residues require cleaning.

Besides combustible soot particles, the filter systems also remove all other particulate matter from exhaust gases that cannot be regenerated, such as ash from burnt engine oil. These residues must be removed from the filter by cleaning.

Easy maintenance enables operators to service and maintain the filters in-house without difficulty, which reduces running costs and downtime, says Robberts.

Since 2013, the company has installed various units throughout South Africa, with several machines also having been delivered to clients in Zambia, Zimbabwe, Namibia and Malawi. John Ratcliffe has therefore gained valuable experience in the installation and configuration of these systems over the years.

John Ratcliffe is a major importer of monoliths for catalytic converters. The company then encapsulates them with cones and flanges or ID/OD stubs, or installs them into client-supplied silencers at its installation centre in Krugersdorp, Gauteng.

Robberts explains that a diesel purifier starts to work at an exhaust temperature of about 120 ºC, after which its efficiency rises very quickly. “At 230 ºC, a purifier removes more than 80% of carbons; and at 300 ºC, more than 90% of carbon monoxide (CO) and more than 80% of hydrocarbons are removed. At 350 ºC, efficiency levels out, with the purifier eliminating more than 90% of both pollutants.”

The heavier a truck’s load, the more pollution it produces, but if a purifier is fitted, greater loads reduce pollution. For example, at 1 400 rpm and a full load, a typical diesel-powered forklift truck produces nearly 3 000 parts per million (ppm) of CO. If a purifier is fitted, pollution is reduced to about 270 ppm – a reduction of more than 90%.

“Significantly reducing the CO levels means increased safety for the forklift operator, since dizziness and headaches are reduced and concentration increases.

The effective conversion of hydrocarbons and aldehydes into harmless gas leads to less eye irritation, and diesel odours are virtually eliminated,” he explains.

Purifiers are available in more than 400 different configurations to suit virtually every forklift truck and bus on the market. In the unlikely event that a standard purifier will not fit, the company can provide a quotation for a custom-made, one-off model.

Whatever shape the purifier takes, the design principles are essentially the same. Each purifier consists of a high-quality grade stainless steel case containing a ceramic honeycomb structure.

This honeycomb design supports a platinum-based catalyst that reacts with pollutants to form carbon dioxide and water, turning these pollutants into harmless elements since it creates a turbulent gas flow to force the maximum amount of gas into contact with the catalyst.

It is at this point that high-technology research and development goes into each purifier model. For the optimum conversion of gases to occur, the maximum surface area of the catalyst has to come into contact with the maximum volume of exhaust gas. “Yet, the gas must not be blocked by the catalyst support in any significant way, otherwise engine efficiency will be impaired,” Robberts says.

The cross section of each cell in the honeycomb is made to particularly fine tolerances – a delicate balance between optimum cell size (to allow the gas to flow freely) and catalyst surface area (to allow the gas to react easily).

Each model is made to particularly heavy-duty specifications and is vibration resistant. Each model is also compact enough to fit into small engine compartments and should not interfere with normal engine maintenance.

Thermal Camera Systems

John Ratcliffe’s South African-manufactured thermal camera systems will also be on display at the show. These systems typically consist of a thermal- imaging camera and a digital video recorder (DVR) encased in a flameproof enclosure, and a liquid-crystal display (LCD) unit, as well as flameproof cables to connect all the components. The flameproof enclosures and cables are entirely designed, developed and manufactured by John Ratcliffe.

The enclosures for the thermal cameras have been certified by an approved certification authority. The systems are modular so that clients can order any combination of cameras and enclosures. The LCD unit and DVR can support up to four cameras per unit.

The systems are particularly useful in the coal mining industry, says Robberts. The FLIR-designed camera units can enhance video feeds in very dark environments to provide clear and detailed video, which will be displayed on the LCD units.

“Our systems can also be easily adapted to suit other low-light and dark environments,” he says.

The company has installed and supplied numerous units to various mining groups and original-equipment manufacturers over the years across a range of industries, from mining and logistics, to food and beverage manufacturers.

John Ratcliffe also offers additional services, including underground and surface vehicle and machine surveys for safety equipment, filtration requirements, exhaust failure and pipework, emissions solutions and puri-mufflers, as well as PTX purifiers and diluters.

Hall M1 Stand 54