Mechanical Technology October 2015

⎪ Hydraulic and pneumatic systems ⎪

Founded only 10 years ago, Highpoint Vacuum is a Sasolburg-based original equipment manufacturer of industrial and municipal vacuum trucks for mineral recovery, waste disposal and cleaning. MechTech visits the manufacturing facilities and talks to engineering manager, Jean Visser, about the company’s designs, its vacuum pumps and the sophisticated hydraulic systems used. South Africa’s mobile vacuum OEM

Shown here under test at the company’s Wonderfontein facilities near Sasolburg is the ‘backbone’ vehicle for industrial cleaning in South Africa, Highpoint Vacuum’s HPVR-1000 Liquid Ring.

H ighpoint Vacuum was found- ed by its current CEO, David Gade in 2004, initially to support the mining industry. Visser explains: “We started out provid- ing capital equipment rentals of vacuum machines on skids and trailers to recover fines on the mines. Once drilling opera- tions are completed at a gold mine, for example, the area is covered with gold- bearing dust. The traditional method of recovering these fines was to wash it into a central area and pump it from there. But gold is heavy, so it does not always move with the surrounding dust and this was a very inefficient process. Using vacuum is far more efficient and, since the product is valuable, more cost effective,” he explains. To overcome replacement component supply shortages and long lead times, Highpoint began to manufacture com- ponents and units for its rental fleet, including its own vacuum pumps. This healthy business has now been split off into Highpoint Rentals. “Then we started to supply vacuum trucks to industrial cleaning companies such as Enviroserv and Bidvest. These companies go into plants and refineries to recover hazardous materials that need

to be collected, transported and disposed of in the safest and most environmentally responsible way. At Holfontein on the road to Delmas, Enviroserv manages the only toxic waste dump in the country,” Visser continues. “Our vehicles are clean- ing ash plants at the older power stations, which contains sulphur that can cause acid rain if it enters the atmosphere, so it has to be collected and disposed of. We are also active in the cement industry with a truck designed for dry bulk such as cement powder and lime. “More recently, we have started to look at the municipal waste and sewage markets, with vehicles for unblocking and cleaning sewage and stormwater drains,” he adds. The vehicle and equipment arm of Highpoint Vacuum is now capable of manufacturing four vehicles at a time on a to-order basis, within a four-month lead time from order to delivery – and production capacity is now more than 20 vehicles per year. “We make vehicles in three basic categories: HPVR Liquid Ring vehicles for hazardous industrial waste; HPVR PDP trucks for dry bulk materials; and HPVR Combi trucks, which combine jetting and vacuum for line cleaning,” Visser tells

MechTech , adding that several variants and customisations of each of these are available. Liquid ring vacuum HPVRs The ‘backbone’ vehicle for industrial cleaning in South Africa is Highpoint Vacuum’s HPVR-1000 Liquid Ring, which has a 12,5 m 3 stainless steel (316L) tank that is kept under vacuum by a 1 200 cfm (2 038 m 3 /h) liquid ring vacuum pump designed and manufac- tured by Highpoint. Explaining how a liquid ring pump works, Visser says that an impeller is rotated inside an eccentric barrel that contains a quantity of liquid ‘sealant’. When the pump starts, the impeller slings the liquid sealant by centrifugal force to the outside walls of the barrel, forming a concentric ring of liquid around the outside walls. The liquid seals off the space between each impeller blade, trapping air in each of the void spaces, called impeller cells. “Because the impeller is off-set from the barrel walls, when the blades are close to the walls, the cells are nearly fully immersed in liquid and the pockets of air are small. But when the impeller tips are further away, the impeller cells

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Mechanical Technology — October 2015