# Calculating diameter of a filter using only flow rate

1. Nov 22, 2008

### mathsTKK

i have got a problem with a calculation involving a filter, i hope you all with lend me a helping hand.

to calculate a diameter of a cylinder is rather easy, but how to determine the size of the water filter knowing only the flow rate of the pipe, diameter of the piping and the pressure of the inlet water

i hope there will be a formula to calculate it to make it easier.

2. Nov 22, 2008

### Topher925

To know the pressure difference across a filter with respect flow rate is not going to be a trivial equation. You would need to know the type and specifications of the filter and this relation would probably be based on experiment. You could model the filter as a porous plug perhaps which equations do exist for.

3. Nov 24, 2008

### mathsTKK

but the filter is made of iron and steel, so i dont think it will fixed the equation, since it is about the porous one. can i know is this a study of fluid dynamic or anything else?

4. Nov 24, 2008

### FredGarvin

Along the lines of what Topher mentioned, if you go through a filter supplier of any kind, they will supply the deta P across their product vs flowrate. You may be able, with some flow testing, to establish an effictive orifice area that would simulate your filter and make the calculations easier.

5. Nov 24, 2008

### Topher925

From my experience (not much), suppliers usually only give you a K value to determine your pressure across the filter. This is a similar value to what suppliers will give with valves, elbows, and other components that will create a drop in pressure. That is, the K is to be used in the equation;

gH = KV2/2

Where;
g = gravity