In the world of control valves, there are numerous designs that will successfully modulate the flow of clean fluids. However, if the fluid contains solids, the scenario becomes more challenging. These ‘clean fluid’ valves are not a viable option for slurry duty, as their complex flow paths can erode or become plugged very quickly.
End users needing to modulate the flow of abrasive slurry must select alternative valves with simple ‘line of sight’ trim geometry, such as ball valves, butterfly valves and pinch valves. These designs provide relatively little flow re-direction and minimal interference with the abrasive slurry.
The downside to typical ‘line of sight’ valves is that fluid velocity through their restricted opening is much greater. This increases the rate of erosion and the valve’s susceptibility to cavitation, resulting in frequent valve replacements, pipe erosion, damage to ancillary equipment, down time and labour costs.
control valve comparison
Knife Gate Valve
SlurryFlo Control Valve
Our patented trim design centralizes flow within the pipe to protect the valve body and downstream piping from wear and erosion. These control valves are custom engineered for application requirements and last 3-10 times longer than other slurry control valves.
Ball valves are a popular choice due to having various orifice geometries available upon order (e.g. Reduced ports, V-ports, Narrow slots, etc), which will provide different control characteristics. However, when throttling, all trim designs will direct abrasive flow into valve body and piping, eroding both.
Butterfly valves are typically selected for applications that have space constraints, as their body designs are among the narrowest in the industry. Despite their dimensional advantage, erosive slurry will be accelerated around both sides of the butterfly disc, significantly reducing the valve’s service life.
Knife gate valves are the least desirable valve for controlling abrasive slurry. When the gate modulates, acute angles are formed between the gate and valve body. These angles produce high fluid velocities, increasing the wear rate significantly. These valves are typically found in large diameter pipe, as they are economical by comparison.
Pinch valves are a mining industry favorite; they work well in most applications and are relatively inexpensive. However, they do have their limitations. As the elastomer sleeve is ‘pinched’, abrasive flow is accelerated within the valve, with the highest velocities (and sleeve wear) occurring in the corners.