Media Filter Nozzle Density

[DAT17]

Does anyone have a rule of thumb for the density of filtration nozzles per m2 for a pressurized dual media filter with a nozzle floor design? The filter will be operating on seawater feed.

 

[sbush]

Rule of thumb (for estimating purposes only): one nozzle per square foot of plan area.

With dual media filters, the backwash rate usually determines how many nozzles will be required to handle the maximum flow rate.

Another tip: always specify heavy-duty stainless steel nozzles or other non-ferrous metal construction. Avoid plastic nozzles, as these have a propensity for failure.

S. Bush

http://www.water-eg.com

 

[DAT17]

Thanks,

my experience has been a bit ropey with stainless corroding in seawater systems, so prefer plastic nozzles although they do suffer from wear and tear (Super duplex or hasteloy simply isn't an option). If I convert the 1 nozzle per square foot to metric this is about 10 per m2,

Any experience with higher densities? say 50 to 100 per m2 (4-10 per ft2)? I'm okay to operate at a filtration rate of 25 m/h with the water quality I have available.

 

[sbush]

DAT17,

Fortunately, I have not had to design a dense nozzle system like the one you are considering. However, if I were in your shoes, I'd be concerned about the support mechanism for all of these tightly spaced nozzles. As you add more and more plastic nozzles, you take away solid material from the support structure. The nozzles should be designed to collect or distribute a certain amount of water volume at a given pressure loss. So, the number of nozzles required will be what it will be. You just have to figure out how to support all of these nozzles in a structure designed to withstand all of the forces that might be encountered during operation.

S. Bush

http://www.water-eg.com

 

[DAT17]

Thanks,

will dig out the old material properties handbook!