mechanical engineers

My simple way it to classes I taught is, "A filter is a Low Micron Strainer and a Strainer is a High Micron Fiter."

A Strainer is a "Rock Stopper" that is normally placed on a Pump Inlet to protect it from debris that will wipe it out instantaneously. Anything that is left in a Tank that was not inspected thourioughy before it was closed up and filled with oil. Hunks of Weld Slag, Shop Towells, Small Tools or miscellaneous small Bolts, Nuts and Fittngs.

I have witnessed failures from all the above over the years, either checking why a pump didn't pass the warranty period or where Cavitation was Loud and irritating the Machines operator.

Hi psroy,

If you are really serious on your post, the proper definition can be found from wekipedia, in fact let me give you some what i picked up, from search sensagent;

Strainer-(n)

1. An apparatus for removing impurities.

2. A filter to retain larger pieces while smaller pieces and liquid pass through.

Filter -(n)

1. Device that removes something from what ever passes through it.

2. An electrical device that alters the frequency spectrum of signals passing through it.

To differentiate is now depending on your understanding on the above, for my personal opinion seems like you can use depending on application. generally speaking I never heard yet that strainer fitted in electrical related like "filter capacitor" you can't say "Strainer capacitor" in a Printed Circuit Board (PCB). or "rain gutter strainer" instead of "rain gutter filter". if you don't agree on my example then as I said, depending on your understanding. HAPPY NEW YEAR!!!!!

Kind regards

Roman

STRAINERS

Strainers are devices made of a single piece of wire mesh, or sheet metal with holes in it. They are designed to removed all the large solid particles from fluids. Most strainers are made of stainless steel or brass.

Strainers cannot remove the small particles like a filter, but they do offer less resistance to flow. They can be installed ahead of valves, pumps, regulators and traps. They are used in pipe lines carrying water, air, gas, steam, and most other fluids.

Many problems in hydraulic systems are caused by impurities (particles, of dirt and sand etc.) in the fluid. Impurities can cause the system to break down. It is less expensive to install a device to remove them, than have to repair some fault.

Strainers are installed on suction lines where the pressure is low. If there is a restriction in a pump suction line, it can stop the fluid getting into the pump.

Low pressure in the suction line can also cause cavitation. Cavitation is a condition where there is not enough fluid at the pump inlet to keep the pump body full. This causes vacuum cavities to form in the fluid stream. Cavitation can cause a mechanical breakdown.

Strainers are also used as screens to keep dirt out of reservoirs. This is common in hydraulic systems

To help prevent dirt getting into the reservoir, always make sure the reservoir cap is replaced after filling.

There are three common types of strainer, they are as follows:

· Cone type. This is the most efficient type of strainer because of its large surface area.

· Disc type.

· Magnetic type. This type is very useful because 50% of all particles in fluids are ferrous.

Before any maintenance work is carried out on a strainer, always make sure that the line has been isolated, and that a work permit has been issued.

FILTERS

Filters are made in various shapes and types. They are used to remove the smaller particles from the fluids. Filters are like strainers but can have several layers. They are made from cloth, metal, and glass fibres, metal powder, paper or glass.

The filter removes the particles by passing the fluid through the porous barriers. All filters change the direction of the fluid as it passes through it. This slows down the particles

There are three common types of filter, they are:

· Edge, or full flow type. These consist of a series of discs with holes in their centres. The discs are separated by a small space.

· Cartridge type. These are similar to car filters.

· Filter bed. These consist of sand and gravel.