INSTRUMENTATION • ELECTRONICS
O
pening, closing, dosing, mixing and distribution are all procedures essential to the process engineering sector. Integral to all these processes is proper pressure regulation. And
the powerhouse behind all these applications is the trusty valve. The right valve can improve efficiency, safety and
profitability. The wrong valve does quite the opposite. There are a great many different pressure control
valves on the market for the process engineering sector but they are not without their faults. Central to many of the issues is the diaphragm, which is essential to the
function of a traditional valve. In a typical regulator, the diaphragm will constantly modulate with the changing pressure, and therefore needs to be flexible to provide accurate control. However, it is this very flexibility, normally provided by a limited range of elastomers, which leads to the fatigue, erosion or embrittlement that most frequently signals the end of the life of the typical regulator model.
A NEW SOLUTION It is the limitations of the diaphragm-controlled regulator that led to the creation of the Oxford Flow model of pressure regulation. The device was invented when Tom Povey, a professor at Oxford University and now the technical director of Oxford Flow, was conducting R&D into various applications such as gas turbines, jet engines and scramjets in partnership with a leading manufacturer. To carry out his research he required pressure
reducing valves (PRVs) that were able to withstand the very high pressures seen in the aviation industry. Unfortunately, finding such a device proved difficult. Not even the best pressure regulators on the market were capable of handling the very high pressures and flows that the tests he was carrying out required. Not prepared to let his research be limited by the
issue, Professor Povey did what any engineer worth their salt would do and set about solving the problem himself. The result was the highly innovative Oxford Flow regulator, which makes the complex and failure-prone diaphragm arrangements found in other regulator designs redundant. In Povey’s model, the diaphragm is replaced by a
direct sensing piston actuator, which not only greatly simplifies the design of the regulator but also removes the main reason cause of failure. In contrast, Oxford Flow’s portfolio of regulator
designs uses a patented balanced sensing piston. One side of the piston is exposed to downstream pipeline pressure while the other side is balanced against a pressure cavity controlled by a pilot regulator. The sleeved piston actuator operates over an optimised feed- hole configuration to provide precise, stable control across the entire operating range. During operation, the piston moves inward, reducing the size of the cavity when the downstream pipeline pressure exceeds that within the pressure cavity set by the pilot regulator. The movement of the piston actuator progressively
covers the feed holes; reducing the flow rate to maintain a stable downstream pressure. When demand increases, the downstream pressure falls below that set by the pilot and the reverse operation occurs; the cavity expands as the pilot feeds it, uncovering the feed holes, which increases flow and maintains a stable downstream pressure. Extensive testing against current market-leading regulators at Oxford University’s Osney Thermo-fluids
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