Valve specialist company Dynamic Fluid Control (DFC) will start local manufacture of valve components designed by pinch-valve manufacturer RF Technologies, in the US, at its Benoni works, in Gauteng province, says DFC mining director Tony Roberts. RF Technologies was bought by DFC in March 2010.
"We aim to achieve 100% South African manufacture of these RF and aiRFlex pinch valves for the local market, while supplying components to subsidiary factories abroad," he says.
The valves are designed to manage higher flow rates at higher-than-normal pressures in mining applications, making the valves well suited to meet local trends toward producing larger volumes of ore and processing them at higher pressures and velocities, he explains.
"The first steps of the project comprise a redesign of valve bodies to reduce weight and the production of initial sleeve samples from locally made moulds. These samples are currently undergoing testing and the finite-element analysis of the redesigned bodies, in the range up to 16 bar, has been completed. The valves are designed to provide flow control, as well as complete flow closure," he says.
Standard face-to-face valve lengths enable rapid interchange with other valve designs and the nonstretch elastomer sleeves deliver higher wear resistance and longer life.
"A standard elastomer sleeve experiences 95% of its wear during the last 10% of valve closing, when stress, flow velocity and abrasion are at their highest, whereas the RF Technologies sleeve incorporates expansion arches to minimise stretching of the sleeve body and extend the valve's life cycle by up to four times," says Roberts.
The self-cleaning, flexing elastomer loosens deposits and eliminates most problems associated with static friction, overshoot and conventional control valve irregularities, he adds.
A wear-monitoring sensor enables preventative maintenance and sleeves can be changed in line to save on labour and equipment costs.
"We will manufacture sleeves locally in sizes from 50 mm to 400 mm to German standardisation institute DIN specifications for the European market and American Society Of Mechanical Engineers specifications for the American market. Larger sleeve sizes will initially be imported. The full RF valve range comprises pinch valves from 25 mm to 1 500 mm in size, in manual and automated configurations, and the RF valve range can be automated and modulated using a supervisory control and data acquisition system," he explains.
Manufacture of the sister aiRFlex valve range will be the second phase of the programme. The aiRFlex valves are capable of withstanding line pressures of up to 4 bar. RF valves are designed to control slurries at pH levels from pH 1 to pH 13, at pressures of up to 40 bar and at temperatures of up to 120 °C. Actuation of the RF valves can be manual, pneumatic, hydraulic or electric, he adds.
Roberts believes that DFC will capture a significant share of the local pinch-valves market in both mining and water treatment applications, and says that the aiRFlex and RF valves are well suited to applications involving corrosive, scaling and plugging slurries and powders.
DFC acquired RF Technologies to allow accelerated penetration of the international market for minerals processing valves, he concludes.