South African firm Dynamic Fluid Control has received Canadian Registration Number (CRN) certification for its RF pinch valve range.

The certification, Canada’s equivalent of the European pressure equipment directive (PED), is expected to boost sales.

Dynamic Fluid Control bought US-based RF Technologies in March 2010 to allow accelerated penetration of the international market for minerals processing valves.

Key component manufacture was transferred to DFC’s Benoni works soon afterwards. Valve bodies across the range were redesigned to reduce weight, and valve tube manufacture implemented up to diameters of 400 mm. Larger tubes are imported.

Manufacture is to DIN (German institute for standardisation) specifications for the European market, to ASME (American Society Mechanical Engineers Standards)/ANSI (American National Standards Institute) standards for the US, and to AS 2129 Tables D and E for Australia, the aim being to achieve 100% local manufacture of RF pinch valves for the South African market while supplying selected components to subsidiary factories abroad.

RF valves and their sister product, aiRFlex valves, are widely recognised as the best available in applications involving corrosive, scaling and plugging slurries and powders, the result of a patented corrugated tube design that delivers between two and four times the life of the standard sleeves of competitive pinch valves.

In mining, the valves are designed to manage high flow rates at higher than normal pressures, making them well suited to local trends toward producing larger volumes of ore and processing them at higher pressures and velocities.

The valves are also extensively used in sewage and effluent applications because of a design that makes them ideally suited to flow control as well as flow closure. General opinion is that they control flow more efficiently than ball, butterfly or diaphragm valves.

Valves across the range can be automated and modulated via a SCADA system.

The full RF range comprises pinch valves sized from 25 mm to 1 500 mm in both manual and automated configurations.

An industry standard face-to-face valve length allows ready interchangeability with other valve designs, while the non-stretch elastomer tube delivers higher wear resistance and longer life.

Whereas a standard elastomer sleeve experiences 95% of wear during the last 10% of valve closure when stress velocity and abrasion are at their highest, the RF tube incorporates expansion arches to minimise stretching of the tube body and extend useful life by up to four times.

The self-cleaning, flexing elastomer action loosens deposits and eliminates most problems associated with stiction, overshoot, and conventional control valve irregularities.

A wear monitoring sensor assists with preventative maintenance, and tubes can be changed in-line to save manpower and equipment costs.

AiRFlex valves handle line pressures up to 4 bar, while RF valves are designed to control slurries in the pH range 1 to 13 at pressures of up to 40 bar and temperatures up to 120°C.

Actuation can be manual, pneumatic, hydraulic or electric.

Picture: Float valve