Empirical research confirms in over a decade of results conducted by several researchers on a variety of conditions, that the most critical factor that determines the creation of surge and waterhammer on closure of the Large Orifice of an Air Valve, or the prevention thereof, is the size of the Orifice at that critical point before closure. This is regardless of whether the system on which the Air Valves are employed is a gravity fed main or pumping system as the Surge and Waterhammer phenomena occur during initial filling as well as during column separation and the subsequent rejoining of water columns.
However, research and extensive computer modeling also indicates that the size of the orifice has to be balanced with the conditions within the pipeline system as too small an orifice may dampen waterhammer but increase mass oscillation (surge) as well as increase filling times for a pipeline whilst too large an orifice will induce waterhammer.
The demand for an air valve design with a multi adjustable orifice to address the above has been understood as far back as the early 1980’s but no successful, practical commercially produced air valve was designed until the advent of AIRFLO Variable Orifice Air Valve Technology.
AIRFLO Variable Orifice Air Valves incorporate a Variable floating shuttle that automatically adjusts the discharge outlet of the valve to the conditions within the pipeline and provides the optimum Orifice diameter at any given point during the performance of the pipeline to ensure effective air release whilst preventing Waterhammer and substantially reducing Mass Oscillation.
AIRFLO Variable Orifice Air Valve Technology is a patented technology that represents a revolutionary way of = addressing Surge and Waterhammer during the release of air. This technology effectively breaks away from the drawbacks and constraints of the Surge damping function of other air valve technologies.
The most significant advancement is the fact that this design does not have a stationary and standardised Orifice and is sensitive to the air outflows of the pipeline. This smooth transition from one differential pressure to the next and the constant adjustment of the Orifice size and therefore the backpressure and the slowing down to the advancing water column as the outflow velocities increases is of major benefit to the pipeline designer as it takes away the guess work of whether the orifice is either too small or too large under varying pipeline operating conditions
The action of the AIRFLO Variable Orifice is such that it will readjust itself under pump trip and column separation conditions thereby allowing for effective air release whilst reducing the magnitude of the surge as well as reducing the amplitude and time period of the pressure wave. This brings the pipeline to a steady state much more rapidly and smoothly without damage to system.
AIRFLO Variable Orifice Air Valve Technology is a substantial advancement into air valve technology and has moved the performance criteria and the technology for air valves ahead in a significant way in essence setting the bench mark for measuring future advancements in air valve technologies.