Surface Area and Pore Size of a Filter Media

Flow is directly proportional to velocity and area (Q=VA). More area results in more flow at a given velocity.

A fine filter will have less flow capacity as there will be less area available as the pore area is increased. More filtering, but higher velocities and head loss across the filter.

The answer depends upon the style of filter in use.

• For a gravity filter, the only option is to increase the footprint of the installation by adding more cells.
• For a cartridge filter, there may be scope to fit a larger bell housing so that longer cartridges can be fitted.
• For a cartridge filter, there may be scope for fitting different filter elements that have a greater surface area per element, no alteration to the housing being needed.

There is no relation between filter area and pore size.

The filter material is a woven material. The pore size is determine by how loosely or tightly its woven. the tighter the weave the smaller particles it will filter out. The surface area is the amount of the material in the filter the fluid will past through. Can be accomplished by increasing the amount of filter media in the same case. Usually though it is done by using a bigger filter.

pore size = the maximum size of particle that will pass through.

eg for a pore of 10μ any thing more than 10μ will be theoritically stopped (it does not really happen that way - for that you must study the beta ratio/multipass test etc) but this is simply put.

Smaller pore means the mesh are nearer - hence the metal vs gap ratio is higher - so the % area for passage of fluid is less. To compensate one has to increase surface area so that same effective fluid passage area is maintained.

This is done usually by

increasing size of element - diameter, length etc

inreasing effective area - by using elements with folds.

1)More flow rate needs more quantity of fluid so it requires more surface area of filter or in other word more fluid rate crossing through more area of filter.

2)If you increase the pore size of filter it gets more flow rate

suggestion:-as per my view to increase the filter surface area not increase the pore size of filter otherwise filtering capacity reduces and tiny particle will cross through filter.

thanks

rcmandal

C.E.(INDIA)

you are pushing a viscous material through small holes to get out the lumps. If you make the holes smaller, the rate of flow is lessened. For example, a one inch pipe with a nylon stocking across it is a filter. If you use a finer stocking, you get a slower flow of oil.

If you want a faster rate of filtration you need to go to a larger pipe, say two inch, same stocking, you now have 4 times the area = 4 times the flow rate. In time lumps fill the holes and the filter must be changed.

They construct the filter to have a larger internal area of filtering meterial. You need to read the filter catalog to choose the filter and filter housing to use if you have a gummy oil and ned more area. Possible an experienced machine man/woman can advise you? If you have a lot of lumps in your oil, you can try two filters in series, One for larger lumps and a fine one for smaller particles.

In general, surface area increase means increase filter element size. There is no relation between pore size and surface area. We can get differet micron filters with same surface area.

The filter can allow more flow if the pressure drop is less. The pressure drop will be slightly higher if less micron filter is used with the same surface area. The flow depends on pressure drop not on pore size.

In hydraulics increase filtration means increase filter size or add parallel filters not to increase the pore size (micron rating)