Filter lifetime

Hi!
I want to know, how can I find out the lifetime of a filter for fluids. Is there a general formula for that, or can it be found out just by practical experiences.
I need to calculate the lifetime of a filter from a conveyor. The filter has an 80-micron mesh openings and the fluid is a water-soluble coolant that flows at 55gpm. The particles are aluminum very small particles that are filtered. From the inside of the filter there are some nozzles that spray water to clean the filter. My duty is to calculate how much this filter will survive. I found on the Internet at

http://www.dpsystms.com/filterlife.htm

a ‘formula’ that looks like calculating the lifetime of a filter but I guess it’s just for a specified type of filter and I don’t think it can be used on any filters... But, that's just guessing...
So, can anybody help me with some suggestions, opinions or information?
Thank you in advance,
Serban

 

[TD2K]

The vendor should be able to give you an idea of the 'dirt' loading capacity of the filter. The difficult part is estimating the particulate loading in the fluid, that's really site specific, it can't be estimated with any degree of accuracy. With those 2 numbers, you can estimate the lifespan. Your lab should be able to quantify the amount of aluminum particles in the fluid.

I suppose you could find out what similar installations experience but it's still going to be driven by how clean 'your' system is.

It sounds like you hav a back wash system, are you talking about how long you can operate between back wash cycles or until the filter has to be replaced?

 

HI.
I was talking about how what's the period the filter has to be replaced. The back-wash system is working continous.
Well, the vendor of the filter is... me I mean, the filter is designed here, and it's the first time I'm doing it. So I don't know the dirt loading of the filter; I know the openigns of the filter and that's pretty much all I know. Indeed, the difficult part is esimating the aluminuium particles from the fluid. I don't have any ideea how to do this...
Thanks for your reply,
Serban

 

[butelja]

You will need, at a minimum, the particle size distribution and the fluid contamination level (particle count in # of particles per volume of fluid). Then you will require testing of your media at conditions similar to the application conditions. There is a standard for hydraulic system filtration (ISO 4572) that outlines the testing procedure.

 

[TD2K]

Perhaps I'm oversimplying it but I'd first look at the dP across the filter. If that isn't being brought back to 'normal' levels by the backwash, you'll need to look at replacing it or doing a more extensive cleaning of the filter.

Then, you'd need to look at the efficiency the filter is removing particles from the fluid since that is its primary purpose. Butelja suggested starting with ISO 4572 (I'm not familar with it but he's a well known name here), take a look at it as a start and see what it says. Particle size distribution is really key to selecting the proper filter but it's much more difficult to measure than a simple estimate of the contaminate loading.