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What is the different Y strainer and Basket Strainer?

Basket strainers are a device typically connected to a pumps suction, which is used to filter out solids or debris larger than the mesh contained within the strainer, which would otherwise damage the pump, internal parts or system. They are used to capture particles which are usually visible to the naked eye, and if smaller, filters are typically used.

 

Strainer Vs Filter
Used to capture larger   solids visible to naked eye Used to capture   particles invisible to naked eye <40 microns which may include salts, or carbon   particles
Designed for a single   type of fluid Can capture   different fluids such as water within oil
Lower pressure drop   enabling use of low pressure designs of pumps Require high   pressure pumping involving high powered positive displacement or multistage pumps   which if selected incorrectly will experience rapid wear by the handling of   such particles
Filter mesh is designed   to be reused over many years Can be single use or   reused through the use of backwashing

 

Working Principle of Strainers

What is a Basket Strainer

Basket strainers are a device typically connected to a pumps suction, which is used to filter out solids or debris larger than the mesh contained within the strainer, which would otherwise damage the pump, internal parts or system. They are used to capture particles which are usually visible to the naked eye, and if smaller, filters are typically used.

Designs consist of a suction inlet, discharge outlet, bolted top cover and casing. The casing holds a filter typically manufactured from wire mesh designed to filter solids which become trapped by the mesh, and sink within the casing. Top covers can be clear or solid. Housings may have a drain at the bottom of the casing where solids will sink to enable them to be drained away.

Basket Strainer Designs

There are various designs known as Y Type, Simplex, Duplex or Backwash.

what is a Y STRAINER

What is a Y Type Strainer?

This type of design is the most economical type which can be mounted horizontally or vertically and is compact in design. Other designs can typically only work horizontally.

They are cast in one piece, meaning they usually have a higher pressure rating tolerance. However due to their design, they produce a larger pressure drop than other variants. 

What is a Simplex Strainer? 

Simplex models are designed for larger pipework, are longer and wider in design containing a significantly larger basket with removable lid for ease of maintenance.

Due to the larger surface area they are designed for capturing larger amounts of solids, and produce lower pressure drops. They can only be installed horizontally, but are easy to inspect and maintain without drainage of pipework. 

What is a Duplex Strainer? 

Duplex models are very similar to simplex strainers in design, however contain two filter baskets which can operate simultaneously or separately. Having twin filters ensures processes can run interrupted whilst they are maintained, as one can continue to function, while the other is maintained. 

 

Self Cleaning Strainer/Backwash / Automatic Strainer Design 

Self cleaning strainers, also known as backwash filters or automatic strainers consist of a strainer, drain, scraper and motor.

Within the strainer there is a hollow shaft with a blade which when the cleaning process is initiated, scrapes along the inside of the mesh removing debris. Simultaneously a bottom outlet valve opens creating an area of low pressure causing the recently freed debris to flow via the bottom outlet valve and be drained away.

The cleaning process is initiated either by a timer, which starts the motor located at the top of the unit to begin the screening process or via a differential pressure switch which senses when the screen is blocked.

Pressure switches are located on the inlet and outlet of the unit and when the inlet pressure is higher than the outlet pressure, the filter is known to be blocked.

These are low maintenance designs enabling the mesh to remain clean and free from solids with long maintenance intervals, without manual

Duplex Strainer Exploded View

Strainer Design Comparison Table – Basket Simplex strainer vs Duplex vs Y Type

Y Type

  Advantages

Simplex Strainer

  Advantages

Duplex Strainer

  Advantages

Backwash / Auto cleaning

  Advantages

Mounted Horizontally   or Vertically Maintain without   draining pipework Mesh can be cleaned   without Process Stoppage Autonomous self-cleaning
Compact in design Lower Pressure Drop Redundancy / Spare   Capacity in Design Zero process   stoppage
Economical Higher Solids   Capture
Disadvantages
During Cleaning as   the strainer is at the lowest point, there is a larger loss of fluid and   system may need to be drained Process must be   stopped during cleaning Bulkier in Design Large units   requiring piping to drain, which may require secondary filtration or dewatering

 

Higher Pressure Loss Only Work   Horizontally Only Work   Horizontally Higher Initial   Outlay

Pressure Loss

Below is a graph indicating single and double Basket strainer Pressure drop compared with Y type designs:

 

At a flow of 10M³H, (166L/min) the pressure drop on the basket type is only 0.3 bar, compared with 0.4bar (40KPA) for a 1″ (DN25) Type