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Bernoulli's with Resistances - model flow between oil filters

by CorneliusRox
Tags: bernoulli, filters, flow, model, resistances
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Apr17-14, 07:18 PM
P: 1
Hey guys,

It's been a while since I was in school and practicing this stuff daily, so bear with me please!

I'm a BSME and I want to model up flow between oil filters.
Currently we use a single oil filter with the same pump we have used forever.
What I am proposing is a higher pressure oil pump (more LPH really) but it will blow holes in the oil filters, so I want to use a two filter setup in parallel.

My question is, how can I model up the resistance of one filter, and then model up the same properties (constant pressure, constant density, constant height) to see how much the flow would change with the second filter.
I am assuming that I can use R=1/((1/r1)+(1/r2)) to model resistance and show that the second filter will drop. The filters are rated at a certain psi and kind of work like a regulator, but regardless, I think this still holds true.

In the end, I'll validate this through dyno and field testing, but I'd like to understand it more first.

Thanks everyone!
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Apr19-14, 08:09 AM
Sci Advisor
P: 1,923
Welcome to PF.
Lubrication oil or hydraulic oil?

A positive displacement hydraulic pump produces a fixed volume flow. The filter will drop some pressure at that fixed flow. The filter should not be used to regulate the flow. Are you using a centrifugal pump ?

It is normal to filter the pump input from the tank, not the output of a pump. You need to protect the pump from dirt in the oil. Why are you filtering the high pressure output of the pump ?

As the filter becomes progressively blocked the differential pressure will rise. You should have a differential pressure gauge across your filters to detect blockage, well before a filter fails and dumps it's load of dirt and fragments of filter element into your system.

You can double the flow for the same differential pressure across the filter by using two filters in parallel. You can often buy replaceable filter elements with a higher capacity, they have the same screw fitting, but have longer canisters.

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