# I have aquestion

1. Aug 8, 2008

### Bashir2008

I have a filter for removal the impurities from the water.. this filter has a cross sectional area about 0.07065m2... and volume is 0.1766m3..

some materials ( beads ) were put inside the filter in order to filter the water.. the packed bed was around 0.60m length..and its volume was 0.046m3 of the filter..

The length of the filter is 2.5m and diameter is 0.30m

the beads ( materilas ) inside the filter need to be washed from time to time.. for this reason we use water or air for backwashing

My question: how could we know how much water or air that we have to pump it to the filter to clean these materials ?

You can make any assumptions if u need

I really need your help to solve this question.

Best regards

2. Aug 10, 2008

### stewartcs

Use a flowmeter.

CS

3. Aug 12, 2008

### FredGarvin

...or a bucket and a stopwatch.

4. Aug 12, 2008

### stewartcs

Ah...the poor man's flowmeter! :rofl:

I've actually done that before!

CS

5. Aug 12, 2008

### FredGarvin

I do it quite often. It's hokey, but it works.

6. Aug 12, 2008

### Topher925

I don't use a bucket, but a container that is graduated. That way I actually know how much water has been collected. :yuck:

7. Aug 12, 2008

### FredGarvin

A 5 gallon bucket does surprising well.

8. Aug 13, 2008

### Q_Goest

lmao. since we're all talking about buckets and stop watches... the most extreme bucket/stopwatch flow measurement I did was at a dock in Rotterdam. Found a rusty old 55 gallon drum that was dumped in a field. Took 20 seconds to fill it with sea water... That ruled out a pump problem for me!

9. Aug 13, 2008

### Bashir2008

Sorry but you misunderstood me.. i did not mean how we measure the flow..

my question was : how could we know how much water we need exactly for this filter... and not how to measure it..

10. Aug 13, 2008

### stewartcs

Probably trial and error. You can obviously calculated the volume of water needed to flush the system, but the amount of time to flow through it in order to clean the beads would be a function of how dirty they are, what type of deposits are in the system, etc..

CS