Without seeing the specification sheet for the device, it would be had to know how to best direct your calculations. But, in any membrane device, a certain portiion f the membrane area is not "active" because it is blocked by a bonding agent or other feature. So, that unused section of the device should not be included in the flux calculation. Best regards, Craigo

Thanks! So that means I can use the active area value for the calculation right?

To calculate the membrane flux you have to find out the area of membrane remains in contact with the feed during separation, this area is called active area and it is used for calculation. You have to subtract the inactive area (covered/blocked by resin to prevent leakage of membrane from sides during module preparation) from total area to find active area.

Dear Sanjay & Craig,

In cross flow filtration that is common to use for UF, NF & RO filtration in different transmembrane pressure, as you know, a metal mesh is put on the membrane surface to fix it. How can we calculate the metal mesh surface area to ignore this membrane surface in pure water flux calculation. Can you explain please?

If the membrane surface was fouled with particulate matter that blocked the cross flow openings, then the obstructed surface would certainly impact the flux. However, when just performing a water flux, the screen spacers in the flow channel will not have any impact on the water flux. This could be born out by comparing the water flux of a disc sample to the water flux of the finished device. There would be a need to allow for some variation as the disc support may have a solid support that would hinder the permeate flow in those areas. Best to use LMH/bar, take the temperature of the water and use relatively low flux conditions to avoid any parasitic pressure losses in the system or devices.