A strainer is a pipe fitting that liquid flows through to clean, filter, or separate it from solids. It can also strain the liquid or any device that acts as a sieve or filter to keep solids from mixing with a liquid stream or flowline. Strainers catch scales, rust, dovetail joints compound, and weld metal in pipes. It protects machinery and processes from their bad effects and reduces downtime and maintenance.
To protect expensive and important equipment like pumps, flow meters, steam traps, control valves, etc., you must use the right strainers in the right places (usually upstream).
Types of Plumbing Strainers
- Y-Type Strainer
- Basket Type Strainer
- Duplex/Twin Strainer
- Back Nut Strainer
- Flange Strainer
- Double Cup Strainer
- Level Strainer
- Drain Strainer
- Stopper Strainer
- Temporary Strainers
- Special Type Strainers
Y Type Strainers
The filter leg of a Y-type strainer connects to the main pipe at an angle, giving the strainer its “y” shape and name. This type is often used in lines with pressure, such as steam, liquid, gas, vacuum, or suction.
Y-shaped strainers usually can’t hold as much dirt as basket-shaped strainers, so they need to be cleaned more often. It is usually not a problem on steam systems, except when rust or debris can get in right after the system is turned on.
Specification of Y Type Strainers
| End Connection | Flanged or Threaded |
| Size | 0.5-inch to 24-inch |
| Filtration Rating | 1 micron to 1000 microns |
| Pressure Rating | Up to 100 PSI |
Configuration of Y-Type Strainer
A Y-strainer can be set up either parallel or perpendicular to the flow of water (Downward flow). It makes it the strainer screen possible to catch particles at the lowest level of the screen.
Advantages of Y-Type Strainer
Cleaning is easy and doesn’t stop the machine from working.
You can choose from various perforations, mesh, and perforation mesh combos to meet the needs of your procedure.
It can be mounted either sideways or up and down.
Application of Y-Type Strainer
A Y-type strainer is useful for gaseous things like vapor, air, and natural gas.
Basket Type Strainers (T-Type)
This strainer works best with large particles and pipes that need to be cleaned often. Most of the time, basket strainers are used at pressures above 1,500 PSI. This strainer has been given different names, such as the tee-type, T-type, or pot type. Also, the basket-type strainers lower the pressure less than the Y-type strainers.
This strainer has a bigger area for straining, which means it can hold more particles. The other benefit of this strainer is that it can hold more debris, so it won’t need to be cleaned as often. One problem with the basket-type strainer is that it can only be put in pipes that run parallel to each other.
Also, the base of the strainers needs to be strengthened for the bigger basket strainers. The basket strainers have a cover at the end that can be taken off so that the filtering element is easy. This makes it easy for them to change the strainer or clean it when it gets full of debris.
When this strainer is put into the steam system, a lot of condensation is collected. A drain stopper and a steam trap on the steam strainers catch the droplets.
Specification of T-Type Strainers (Basket Type)
| Pressure Rating | 125 PSI, 150 PSI |
| Size Range | 40mm (1½”) To 300mm (12”) |
| Body | Brass |
Application of T-Type Strainers (Basket Type)
Basket strainers can only be put on parallel pipes, and the base of a larger, bulkier basket strainer must be made stronger.
The cover of a basket strainer can be taken off so that the filtering part is easy to get to if it needs to be changed (due to stocked-up debris). When basket-style strainers are used on steam systems, they can collect a lot of condensates. So, steam strainers usually have a stopper for the drain and a steam trap to catch the droplets.
Duplex/Twin Strainer
As the name suggests, the duplex or twin strainers use two strainers to do the job. This is also a basket strainer, but it is called something else. When many things are going on at once, and it’s hard to clean between processes, the duplex strainers are a good choice. When you have two strainers, the straining process can be moved to the other basket when the first one is full.
So, the strainer ensures the filtering process will continue until the first basket is cleaned or replaced. This strainer has either plug-type valves or ball-type valves. This makes it possible to change the water flow from one basket to another. These strainers can only be put in pipes that are parallel to each other.
Also, they are great for pipes that are big or bulky. These strainers are also great for pipelines or programs that need to run all the time. When one basket gets full, the other is ready to take over.
Specification of Duplex/Twin Strainer
| Pressure | Up to 2500 psi |
| Temperature | Up to 560 0C |
| Mesh size | 37 – 6730 microns or Mesh 3 – 400 (US) |
| Material body | Iron, Bronze, Carbon Steel, and Stainless Steel |
| Material mesh | Stainless Steel |
| Connection | Flange Flate Face (FF) & Raised Face (RF), Ring Type Joint (RTJ), Threaded, Buttweld, Socketweld |
Application of Duplex/Twin Strainer
Basket strainers can only be put on parallel pipes, and the base of a larger, bulkier basket strainer must be made stronger.
The cover of a basket strainer can be taken off so that the filtering part is easy to get to if it needs to be changed (due to stocked-up debris). When basket-style strainers are used on steam systems, they can collect a lot of condensates. So, steam strainers usually have a stopper for the drain and a steam trap to catch the droplets.
Back Nut Strainers
A back nut strainer looks like a back nut on its top half and is attached to the plumbing system at the bottom of the sink. Its nut is good for the draining system of a house sink because you can turn it.
Standard Size of Back Nut Strainers
| Bigger Size (inches) | 4.3×1.2×3.1 |
| Smaller (inches) | 3.4x1x2.3 |
For example, if strange things got stuck in the filter and stopped the water from going where it was supposed to go.
In this case, the stuck particles will fall out when the rear nut of the strainer is turned.
Flange Strainers
The flange filter is one of the sink strainers that are the most expensive. It is one of the sink strainers with a lot of great features. It works as a filter, back nut, removal, and water stop. This makes it a sink strainer that does everything. Most flange strainers are black with a matte finish.
It has a rubber ring under the cover to keep water out. To stop the water from flowing, push the nut into the drainage system so that it sticks. It has dimensions of 3x3x3, 4x4x4, or 5x5x5 inches.
Advantages of Flange Strainers
- Easy to put up and take down
- It can fit some sinks that have garbage disposal hooked up to them.
Double Cup Strainers
A strainer with two cups is something special. There are a lot of rubber and steel rings in it. It can be changed because it has two strong strainer cups and a rear nut filter. Most of the time, one cup is attached to the hole for the drain. The second one goes on top of the one that is linked. It can be taken off to clean.
The top cup is a wall, and the bottom holds things. It is usually built and made to keep the sink’s drainage system clean and free of debris. A two-cup strainer will not let anything big through.
Stainless steel & brass is used to make most of this strainer. It keeps rust from building up. It is 4x3x1 inches. Installing it is easy, and you won’t need a plumber’s help.
Advantages of Double Cup Strainers
- Very durable
- Stops debris from entering your pipe
- Calm to clean
- Can stop sewerage water flow
Level Strainers
If you want a standard sink strainer, you should get a level strainer. The level strainer doesn’t use a specific machine system or any other type of rubber technology. It is 6x4x1 inches. It only has a big net to keep big and small things from falling into the sink.
The level strainer works with a circular plastic stopper that stops the water flow when needed… It seems to have a simple structure and no nut system. Some level strainers have an extra rim that stops water. A level strainer is the best way to keep drains from getting clogged.
Advantages of Level Strainers
- Very Reasonable
- Easy to put up and take down
- It can stop any trash, no matter how big it is
Drain Strainer
Drain strainers work very well and can stop food waste and other solids from going down the drain. Drain strainers have a strong metal screen or mesh that keeps things from going down the drain.
This strainer is the most popular type because it is the easiest to use. Just put it on the drain, and it will easily filter food. But you should know that a drain strainer can’t stop water from going through. Like level strainers, there is no way to permanently attach them to your drain, so they might float when your sink is full of water.
Stopper Strainer
The stopper strainer sounds exactly like a flash strainer with a built-in stop. Most stoppers have a screw in the middle that separates or connects them. It is 6.1x5x6.1 inches.
When the plug is in place, water can freely flow through the drain, and the strainer catches debris. When the sink is plugged in, the water stays there until the plug is pulled out.
Advantages of Stopper Strainer
- Very Reasonable
- Easy to put up and take down
Temporary Strainers
Temporary strainers are the best choice when money is tight because they cost less. Between the pipe and flanges are these strainers.
There are three types of temporary strainers, each with a simple shape.
- Flat
- Conical
- Truncated
Most of the time, these strainers are lower to the ground than basket strainers. The strainer tends to get messed up because so many things are going through at once.
Special Type Strainers
Several other special types of strainers on the market are also used for different things. The strainers are grouped based on their obvious features and the pipe systems. In some situations, you need to use a certain kind of strainer.
- Magnetic Strainer
Magnetic strainers work well to stop pump seals from wearing out too quickly. Magnets make a magnetic field, which draws iron molecules to it. Iron molecules cause pumps to rust, which causes them to break.
- Offset Strainers
Offset strainers work better on pumps close to the ground and require strainers. The output of this strainer is low, but the intake is high. Even though the pump is close to the ground, there is less chance of contamination.
- Micronic Strainers
Micronic strainers get rid of particles as small as 5 microns by using a very small mesh. People use this kind of strainer to do things like separate water from fuel.
- Reducing Strainers
With reducing strainers, you don’t need reducers. Using these strainers, you can reduce the pressure drop that happens when you cut the size of a pipeline.
Material of Construction
Cast iron is the most common material for strainer bodies because it is cheap to buy. It is used in systems where the water pressure and temperature aren’t too high and where there aren’t a lot of thermal or mechanical shocks. Cast iron is mostly used for bigger potable water lines and many systems that don’t use potable water.
Bronze: For use in brackish, salty, and seawater, bronze is the best choice. It is often used to get water that can be drunk.
Carbon steel is used in places with high temperatures and pressures and where the material needs to be resistant to thermal and mechanical shocks.
Chrome-moly steel: It is used when temperatures and pressures are high.
Stainless Steel: Often, stainless steel is used where erosion is a big problem.
Strainer Screens
Strainers are of two types:
- Perforated Screen
- Mesh Screen
Perforated Screen
The sheet is rolled into a tube and welded together in a few places. These screens usually have holes between 0.8 mm and 3.2 mm in size. So, screens with holes can only be used to clean out general pipe debris.
Mesh Screen
A grid or mesh is made from small pieces of wire. It is usually put on top of a screen with holes, which acts as a cage for the mesh. You can make much smaller holes using a mesh screen instead of a perforated screen. It is possible to make holes as small as 0.07 mm. After that, they are used to get rid of small particles that would otherwise get through a screen with holes.
Key points for choosing proper Strainers
Flow Velocity
Flow speed and a pressure drop directly affect each other. The flow rate is likely to be slower if the material is thick.
Open Area Proportion
How long the strainer can work well before it needs to be cleaned is based on the ratio of open area to capacity. This factor also affects how much pressure loss there is inside the strainer.
Knowing how much the strainer is open is important because it shows when the mesh needs to be cleaned or replaced. When a strainer gets clogged, the pressure drops by a lot. When the Open area proportion is high, the media has a lot of particles or is very sticky.
Mesh Size
The size of the mesh determines how much the strainer can filter. The smaller the mesh, the more force it can hold. To find the mesh size of a screen, count how many holes there are in one inch. On the other hand, a 10-mesh screen has ten holes over that one-inch line.
The plus sign shows that molecules with a diameter bigger than that number can’t get through the mesh. A number with a minus sign means only particles smaller than that number can get through. For example, a +400 mesh means molecules 37 microns wide can’t get through. Molecules with a diameter of fewer than 250 microns can get through a -60 mesh.
Link Between Strainer Kinds and Pipe Alignment
Pipes are only sometimes set up so that they are horizontal. Only when the flow is going downhill can the pipes be in a straight line.
On the other hand, the best strainers for vertical pipes are the Y-type or tee-type basket strainers. This makes it easy to catch the particles and ensures the trash doesn’t flow back upstream.
On the other hand, the strainer is placed as low as possible so debris can be flushed out easily.