To meet mines’ and processing plants’ continuous need for robust and chemi- cal-resistant products, thermoplastic pipeline products supplier Astore Keymak will start supplying Italian thermoplastic valves manufacturer Formatura Iniezone Polimeri’s (FIP’s) flanged DIALOCK (DK) diaphragm valves to the local mining industry from June.

These valves have monolithic flanged, one-piece bodies and are suitable for shutting off and regulating aggressive chemical mediums. Astore Keymak product manager Francois van Vuuren tells Mining Weekly that the valves are also internally self-draining, which reduces chemical corrosion that is often a challenge at mines’ processing plants.

He adds that the valves are suitable for use in aggressive chemical environments where acids are used, such as processing plants, which requires thermoplastic material products to withstand the damage.

“Previously, customers could get a flanged-valve option from FIP, but it was not as integral as the new DK flanged valve. The company kept the dimensions similar, allowing for easy replacement of existing FIP valves. The valves’ dimensions are also compatible with competitors’ valves, ensuring seamless replacement.”

Easy replacement is also a crucial factor, since mines often need to replace cheaper, low-quality products imported from the Far East. Van Vuuren says clients are not always aware of the risks of using such valves, ultimately resulting in higher costs, as the products have to be replaced after only a few months in operation.

The DK valves also have the advantage of optimised linearity and by having an improved characteristic curve, the hand wheel allows for highly sensitive and precise adjustment during operation.

Moreover, to make customers more aware of considering relevant factors when choosing a valve or valve brand, Astore Keymak holds roadshows nationally across its ten branches. “We share our product knowledge and introduce clients to new products,” he notes, adding that the company’s first roadshow for the year will be in the next month or two.

Van Vuuren avers that it is essential for Astore Keymak to become specified suppliers to mines, amid a competitive local valves market. “Six years ago there used to be seven or eight major valves suppliers, now there are between 15 to 20. The added advantage is that Astore Keymak is the sole distributor of FIP’s industrial valves in South Africa.”

DK Advantages
The DK system on the diaphragm valves entails a hand wheel that is equipped with a patented, immediate and ergonomic locking device, allowing for it to be adjusted and locked into more than 300 positions.

“The design and components of the hand wheel make the operating mechanism waterproof, isolating all the internal metal parts from contact with external agents, such as chemicals or acids,” emphasises Van Vuuren.

The automated operating mechanism – in this case the piston actuator – consists of fibreglass-reinforced polypropylene and is available in a single- or double-acting version.
Further, the DK diaphragm valves range includes a DKL “limited edition” valve that is equipped with a hand wheel stroke control system, allowing for the maximum and minimum flow rates of the valve to be changed. This system also prevents excessive pressure on the diaphragm during closing.

“The system enables the valve stroke to be modified using the two independent adjusting screws, which determine the mechanical limits of the valve during opening and closing.”

The DK valve body has an optimised internal fluid design that increases performance by up to 90%, compared with that of previous valve models, and is available in unplasticised polyvinyl chloride, chlorinated polyvinyl chloride, polypropylene homopolymer and poly- vinylidene fluoride.

“The new internal geometry of the valve allows for greater efficiency, which results in substantial increases in the flow coefficient values (Kv100) and a resulting reduction in pressure loss,” explains Van Vuuren.

He adds that the design of the internal profiles of the valves, which are free of “dead areas”, reduces the risk of deposit build-ups and diaphragm contamination or damage through crystallisation, leaving the inside of the valve clean.

Actuator Facts
Van Vuuren highlights that key features of the DK valve actuator include six independent cartridge springs, arranged radially to uniformly distribute the load on the piston.

The actuator consists of a dual-function main gasket and a piston seal that ensures the gasket does not move but sits securely on the actuator cylinder instead of the piston. An external seal ensures that the gasket is positioned above the threaded joint between the bonnet and cylinder, which, in turn, ensures that the coupling is not stressed by the pressure inside the actuator.

Moreover, the actuator also has a high-strength stainless steel stem with a double- seal O-ring. A floating pin connection between the actuator stem and diaphragm prevents concentrated loads.

“The piston in the actuator has an FIP IXEF high-strength design. The high-quality finish of the external surface guarantees perfect stability over the seal and ensures a long working life without any actuator maintenance,” Van Vuuren concludes.