The first thing to determine is the flow rate. Any flow rate over 150 gpm will most likely require a basket strainer because of pressure drop considerations.  Strainers are usually sized so that their start up pressure drop is no greater than 2 psi, with a line velocity not to exceed 8 fps. On a per size basis, basket strainer will have less of a pressure loss than Y strainers. On the product pages for strainers there is a button for an automatic sizing calculator based on pressure loss.

The next application parameter is difficult to determine but is important. You need to know just how "dirty" is the process media. Y strainer screens are smaller than the strainer baskets used in basket strainers. So, in a given application, a basket strainer will go longer between cleaning than a Y strainer will.

This is also important because cleaning the screen of a Y strainer can be a messy affair compared to a basket strainer. Remember the Y end of the Y strainer must be below the pipeline, pointing down, to trap the debris. This means that when the cap is removed to clean the screen any fluid trapped in the strainer drains out and must be dealt with. Depending on the process media, and the location of the strainer, this can get nasty.

This problem doesn't exist with a basket strainer. The hand removable cover of a basket strainer is on top. Just screw off the cover and lift out the gasket to clean or replace it.

Metal Y strainer often have a "blow down" connection on the cap to clean the screen without removing the cap. This is not recommended with a plastic Y strainer because the hole in the cap would weaken the strainer and effect its pressure rating.

So, if the application requires infrequent cleaning and the process media is environmentally safe, a Y strainer should work. If the opposite is true and the sterner will be cleaned often and the fluid is less than "friendly", a basket strainer is the answer. If in doubt, select the basket strainer every time. It may cost a bit more but will stay in service longer between clean outs and it will be easier to clean.

Another thing to consider is if the system has to run continuously and cannot be shut down. If the application requires continuous flow, then the only real choice is a duplex basket strainer.

Size of the perforations in the screen or basket is another consideration. Our plastic Y strainer screens are only available in 1/32" perforation. Basket strainers, depending on size, come with 1/32", 1/16", 1/8" or 3/16" plastic baskets.  Stainless steel baskets and screens are available from 40 microns up to 1/2" for both basket and Y strainers.

Installation orientation of the strainer must be considered. If a vertical installation is planned, a Y strainer is the one that will work. They can be installed either vertically or horizontally. A basket strainer must be installed horizontally.

Whether you choose a Y or Basket strainer a spare basket or screen should always be purchased at the same time. There are several good reasons for this. A spare screen or basket makes clean out easier. Just remove the dirty one and install the clean spare one. The line is back in service quicker and the dirty screen can be cleaned later on. And remember, nothing is quite as useless as a strainer without a basket or screen. It breaks or get lost or damaged, the line is out of service until a new one is located, purchased and installed. Having a spare on hand avoids this down time problem.

Y Strainer or Basket Strainer? A quick look at your application parameters and you'll be able to select the right one.