As a Strainer manufacturing company for over 12 years, we are used to people referring to our products as Strainers or Filters interchangeably. As we manufacture Strainers only, this has never been an issue for us. We know what we can manufacture and what we cannot. Those that we can, we do and the rest, we don’t. What can be simpler than that?
However, our marketing folks decided that this debate should be laid to rest once and for all, and we should be the ones to do it. So, they googled around the net and as usual, got thoroughly confused. We quickly realized that unless that we do something about this, we will soon have our marketing folks selling stuff that we cannot make! We had to do something and fast.
Time to get in touch with StrainerMan – the oldest member in our team, who claims to know all there is to know about Strainers, as a result of over 30 years of industrial experience. We are not sure about his claims, however. He is old enough, for sure, but any question about his credentials results in a 2 hour acrimonious harangue. But we figured this one should be well up his alley. Surprise, surprise, he did actually come up with stuff, which completely puts the question to rest. Our marketing guys can now stop being clueless (about this at least!)
This is what our StrainerMan Says –
First, some Filtration 101
“FILTRATION is the process of removal of suspended solid particles from a fluid – Liquid or Gas”
There are many types of filtration techniques – Centrifugal Filtration, Electrolytic Filtration, Mechanical Filtration etc. There are two types of mechanical filtration techniques – Surface Filtration and Depth filtration. Surface filtration is the technique where a sieve or a mesh or a perforated sheet is inserted into the fluid flow and the debris, which is larger than the hole-size, is collected on the surface presented to the fluid flow. Depth filtration is a technique where the debris is collected throughout the body of the filter element and not just the surface. Strainer is a surface filtration device. A Cartridge Filter or a Charcoal filter is a depth filtration device.
A Strainer is one type of a Filter. All Strainers are filters, but all filters are NOT Strainers.
With this clear in our minds, we can draw out some inferences…
- Strainers can be cleaned and reused, whereas ‘most’ depth filtration devices are ‘use and throw’ types (the filter elements are thrown away). Of course, there are some exceptions, where you have a backwash arrangement.
- Strainers are typically used for filtration of debris above 10 micron sizes. Anything finer, needs other filtration techniques. This is because, at sub 10 micron sizes, the meshes are too fine for the operating pressure – typically.
- Pressure drop across Strainers are lesser than the depth filtration devices.
Now that StrainerMan has delivered for us (for the first time, I think), we have decided to post a series on Strainer selection parameters in the coming weeks. Keep your eye open!