Need to buy panel diffusers to get high efficiency? Think again.

By: Tom Frankel
Post Date: February 10th 2010

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There is a common misconception in the marketplace about what type of diffuser is the most efficient. Many very intelligent people are led to believe that rectangular panel diffusers are more efficient than discs or tubes. This may have been true at one time…

SSI has some recent examples of independent SOTE tests conducted by ATC, SA, who are a well respected firm in this field.

DISCS – Munster, Louisiana
AFD270 9″ disc diffuser, 0.65 SCFM (1.1 Sm3/hr)/diffuser, 19 ft (5.8m) diffuser submergence, SOTE = 2.48%/ft. (8.12%/m) at 8″ WG (20 mbar), SAE = 6.02 KgO2/kWh headloss

TUBES – Owasso, Oklahoma
AFTS3100 3″ tube diffuser, 1.5 SCFM (2.5 Sm3/hr)/diffuser, 13 ft (4m) diffuser submergence, SOTE = 2.44%/ft. (8.02%/m) at 8″ WG (20 mbar), SAE = 5.97 KgO2/kWh headloss

In summary, low flux rates produce high SOTE. The difference between panels and discs or tubes as we see it, is that panels may have very high headloss. This headloss significantly reduces their SAE. SAE is the wire to water efficiency of the system. In fact, SAE is the only number that counts!

In side by side tests conducted by an independent testing firm in the UK, SSI AFD270 consistently beat a well known panel diffuser in SAE. After reading this, that should come as no surprise.