Single perforated screen with round holes for straining large particles
Fine and Medium Strainers
Backup tube and wire mesh over-screen for finer particles.
Wire mesh over-screen straining elements are reinforced with a heavier
gauge, perforated backup tube to provide additional support.
Difference between a filter and a strainer:
The basic difference between a strainer and filter is the degree of filtration.
Both are devices designed to remove particles from a liquid or gas. Strainers are intended to remove larger particles, and filters remove much smaller particles, which you normally can’t see.
Strainers are generally installed to protect your products or process equipment like control valves, pumps, flow meters, homogenizers, etc.
Strainer selection criteria:
• Particle retention (Mesh size to be used in the strainer)
• Amount of free open area
• Fluid properties (Viscosity, flow rate, etc.)
• Location of the strainer
• Pressure drop allowance
See below the Screen reference chart
What is the mesh size?
It is the number of wires per inch in both a vertical and horizontal direction.
What does 'free open area' mean?
Strainers can’t be selected according to the pipeline size!
The term "Open Area Ratio" or "Open Area to Pipe Area" is a measure of relative particle-holding capacity and is usually between 2 to 4 times the inlet pipe area (cross sectional area of the pipe). Anything less may cause excessive pressure drop and short filtration cycle time.
What’s effective filtration area?
It is the total area of the filter element that is exposed to the fluid flow.
The larger the filter area, the longer filtration cycle time.
What is the effect of adding the mesh over the screen to the strainer element?
The mesh over screen reduces the effective opening of the strainer backup tube.