Sewage pipelines get protection

July 2012 Valves, Actuators & Pump Control

Dynamic Fluid Control has launched the Vent-O-Mat series RGX II, a second generation air-release and vacuum-break valve designed specifically for sewage pipelines. The valve controls air release, protects the pipeline against vacuum and alleviates the effects of potentially damaging surges. An entirely new product, the design of RGX II incorporates market feedback into proven Vent-O-Mat valve technology, itself the result of decades of comprehensive research.

RGX II originated in response to a requirement to overcome the clogging of sewers in the USA, caused by a build-up of grease and fat. To counter this, internal components comprise solid polyethylene floats and dynamic O-ring seals that do not jam or distort ensuring reliable operation over the life of the valve. Rugged design eliminates valve failure, breakage, premature closing, and incomplete venting and the associated pressure shocks common to other sewage air valves. On the outside, a short, compact valve body has been achieved without compromising the pressure rating.

Product development took place over a three-year period, the goal being to design a compact valve that would overcome clogging while maintaining a full bore inlet and outlet, and at the same time incorporate the integral anti-shock device for which Vent-O-Mat is famous. The result is a sewage air release valve with an anti-shock and anti-surge mechanism fitted as standard to protect against damage from the high pressure transients associated with high velocity air discharge. The mechanism automatically reduces the surge caused by liquid column separation and liquid oscillation.

RGX II features full port opening, with large orifice diameters equal to the nominal size of the valve (i.e. 150 mm valve has a 150 mm orifice). This ensures the highest possible intake of air into a draining pipeline, protecting it against premature mechanical fatigue and pipeline collapse.

In operation, the valve protects a pipeline under all conditions, irrespective of the state of the water column within it. The valve is biased towards an anti-surge action, allowing controlled air release through an orifice aerodynamically engineered to throttle air discharge when the velocity of the approaching liquid would otherwise become too great and induce unacceptable pressure rises. This throttling action increases resistance to the flow of the approaching liquid, which subsequently decelerates.

The opposite extreme is when a pipeline experiences liquid column separation due to pump stoppage. Under these conditions, RGX II allows air into the pipeline, but throttles its discharge as the separated column begins to rejoin, reducing the impact velocity and alleviating high surge pressures.

RGX II is offered standard in either 304 or 316 stainless steel with other materials available on request. as well as in any exotic material required by the customer. Model sizes range from 50 to 200 mm.

For more information contact Henry Smith, Dynamic Fluid Control, +27 (0)11 748 0200, [email protected], www.dfc.co.za

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Sewage pipelines get protection

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