Filtration grades
20 gsm meltblown: fine fibre at minimum weight
20 gsm meltblown is the light filtration layer: enough fibre density to catch particles, low enough pressure drop to breathe through.
At a glance
Specification at a glance
| Property | 20 gsm typical range | Note |
|---|---|---|
| Fibre diameter | 1.5 to 3 µm | Affects efficiency |
| Filtration efficiency | 60 to 80 % at 0.3 µm | Uncharged, NaCl method |
| Pressure drop | 20 to 35 Pa | At 32 l/min |
| Tensile MD | 8 to 14 N/5 cm | Low, needs support |
| Oil absorbency | 8 to 12 g/g | Grade dependent |
| Handling | Needs a carrier layer | Too weak to run alone |
Why meltblown is always a layer, never a fabric
The fibre is fine by design, which is what gives the filtration efficiency, and fine fibre means low tensile strength. A 20 gsm meltblown web has roughly a third of the tensile of a spunbond of the same weight, so it is always laminated or sandwiched between two stronger layers.
Efficiency versus pressure drop
The two numbers move together. Raising weight or reducing fibre diameter raises efficiency and raises pressure drop, which the end product feels as breathing resistance or as fan power. A specification that fixes only efficiency will be met with a web the machine cannot push air through.
Absorption uses
For oil and chemical spill absorption the same structure works because the fine fibre creates capillary volume. The requirement flips from pressure drop to absorbency and retention under load.
Other weights in this range
This grade sits in the Meltblown range. Buyers comparing across weights usually ask for two or three of these at sample stage, because the decision is made on the converting line rather than on the data sheet.
- 25 gsm meltblown - The middle layer of a three-ply medical mask is meltblown, usually 25 gsm, and.
- 30 gsm meltblown - 30 gsm meltblown trades airflow for capture. It is used as a pre-filter ahead .
Check the grade against your line
Send the application, the width and the monthly volume. We reply with the tolerance, the batch test values and a ship date.
Questions
Common questions
Is 20 gsm meltblown enough for a mask?
It is used in lighter masks, but a medical mask middle layer is usually 25 to 30 gsm and electret charged to reach the required bacterial filtration efficiency.
Can it be used alone?
No. It is too weak to convert alone and is always laminated to a spunbond or a support scrim.
Does it hold a charge?
Electret charging is a separate process applied to the web. Ask for the charged efficiency, not the uncharged number, if the product needs it.