How do CAV filters work?

[Just_sayin']

I've read a lot on here about the diesel bug and it's got me wondering.

Has the fuel in the bowl already been filtered or is it neat from the tank, then drawn up through the filter?

I like the second option as drawing off some fuel from the bowl would show you the true condition of the fuel whereas if it was filtered first, clean fuel could just suggest that the filter is working properly, only for it to be actively clogging.

 

[KellysEye]

>Has the fuel in the bowl already been filtered or is it neat from the tank, then drawn up through the filter?


Neat from the tank.

 

[pvb]

Has the fuel in the bowl already been filtered or is it neat from the tank, then drawn up through the filter?

The filter head has arrows on the ports, indicating fuel flow. If properly plumbed, the fuel in the bowl has been filtered. A lot of people don't understand this. The reason is that the filter medium acts as an agglomerator of minute water particles, helping them to form into droplets which will fall to the bottom of the bowl. This old CAV publication explains it...

 

[PCUK]

There are two systems. The agglomerator as described above which filters the fuel through the element and then into the bowl. Then there is the filter that passes fuel into the bowl down the centre where it is filtered as it goes up through the element. The agglomerator is the first filter in the line followed by the filter usually fitted on the engine block.

 

[Just_sayin']

Thanks guys.