Valves improve filter reliability

Rotorflush Filters' new valve senses when solids are beginning to build up on the filter screen faster than the self-cleaning jets can clear it.

Rotorflush Filters has developed a two-inch balanced stainless steel valve which will throttle and shut off pressures up to 10bar with only a 50mbar pressure differential across the sensing diaphragm.

The valve is configured to be normally open but can be also be configured to be normally closed.

The valve is an addition to Rotorflush's range of self-cleaning filters and is being supplied as an optional extra to its range of filterpumps to give absolute reliability to the self-cleaning filter in the most difficult of conditions.

The valve, which has a 50mm orifice, is constructed entirely of stainless steel with the exception of the diaphragms.

It consists of a stainless steel body with two balancing rolling diaphragms, which almost eliminate friction losses.

There is a larger sensing diaphragm, one side of which is open to the environment.

The other side connects to the Rotorflush filter.

In operation the valve normally remains fully open allow the Rotorflush Filterpump to give full output.

However on sewage works during storms, for example, the sewers can be flushed out, causing high levels of solids to enter the sewage works.

Occasionally this can overcome the Rotorflush Filterpump, causing it to block.

The valve senses when solids are beginning to build up on the filter screen faster than the self-cleaning jets can clear it.

This build up causes the pressure inside the filter to drop and this causes the valve to start throttling the output of the Filterpump, allowing it to continue to work without interruption.

When the solids levels in the water start reducing the valve opens again, restoring full flow from the Filterpump.

The valve is also applicable to Rotorflush's range of self-cleaning inlet filters for surface mounted pumps.

Operating in the normally closed configuration, the valve only opens when it senses the screen is beginning to blind.

Just enough water is sent to the backwashing jets to keep the screen clean, drastically reducing the proportion of the pump's output that is sent to the filter for cleaning purposes.

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