Filter media comprising a pre-filter layer
Filter media comprising a pre-filter layer and related components, systems, and methods associated therewith are provided. In some embodiments, the pre-filter layer may be designed to impart desirable properties to the filter media, such as a high gamma and/or long service life, while having relatively minimal or no adverse effects on another property of the filter media that is important for a given application. For instance, a pre-filter layer may be used to improve the upstream removal of fine particulate matter, which may clog a downstream efficiency layer comprising submicron fibers and reduce filtration performance. The pre-filter layer may be configured to increase service life and/or increase the gamma of the filter media. Filter media, as described herein, may be particularly well-suited for applications that involve filtering air, though the media may also be used in other applications.
1. A filter media, comprising:
a pre-filter layer comprising first fibers having a median diameter of less than or equal to about 2 microns, the pre-filter layer having a thickness greater than or equal to about 20 microns, wherein the pre-filter layer has a basis weight of less than about 30 g/m 2 and an initial DOP efficiency of less than or equal to about 90%; and
a second layer comprising second fibers having a median diameter of less than or equal to about 1 micron, wherein the second layer has an initial DOP efficiency of greater than or equal to about 60% and wherein the initial DOP efficiency of the second layer is greater than the pre-filter layer.
2. The filter media of claim 1 , wherein the first fibers comprise synthetic fibers having a median fiber diameter of greater than or equal to 0.5 microns and less than or equal to 2 microns.
3. The filter media as in claim 1 , wherein a surface area of the pre-filter layer is less than or equal to 3 m 2 /g.
4. The filter media as in claim 1 , wherein the initial DOP efficiency of the pre-filter layer is greater than or equal to 30% and less than or equal to 80% when in an uncharged state.
5. The filter media as in claim 1 , wherein the first fibers comprise meltblown fibers.
6. The filter media as in claim 1 , wherein the median fiber diameter of the second fibers is less than or equal to 0.2 microns.
7. The filter media as in claim 1 , wherein the pre-filter layer has a gamma of greater than or equal to 7 and less than or equal to 15 when in an uncharged state.
8. The filter media as in claim 1 , wherein the pre-filter layer has a basis weight of greater than or equal to 5 g/m 2 and less than or equal to 30 g/m 2 .
9. A method comprising filtering a fluid using the filter media of claim 1 .
10. The filter media as in claim 1 , wherein the second fibers comprise electrospun fibers.
11. The filter media as in claim 1 , wherein the second layer has a basis weight of greater than or equal to 0.5 g/m 2 and less than or equal to 10 g/m 2 .
12. The filter media as in claim 1 , wherein the second layer has a thickness of greater than or equal to 0.001 mm and less than or equal to 0.5 mm.
13. The filter media as in claim 1 , wherein the second layer has a gamma of greater than or equal to 40 and less than or equal to 75.
14. The filter media as in claim 1 , wherein the initial DOP efficiency of the second layer is greater than or equal to 95% and less than or equal to 99.99999%.
15. The filter media as in claim 1 , wherein the filter media has a basis weight of greater than or equal to 60 g/m 2 and less than or equal to 150 g/m 2 .
16. The filter media as in claim 1 , wherein the filter media has a thickness of greater than or equal to 0.1 mm and less than or equal to 2 mm.
17. The filter media as in claim 1 , wherein:
the first fibers comprise meltblown fibers;
the second fibers comprise electrospun fibers;
the pre-filter layer has a basis weight of greater than or equal to 5 g/m 2 and less than or equal to 25 g/m 2 ; and
the second layer has a thickness of greater than or equal to 0.001 mm and less than or equal to 0.5 mm.
18. The filter media as in claim 1 , wherein:
the first fibers comprise synthetic fibers having a median fiber diameter of greater than or equal to 1 micron and less than or equal to 2 microns;
the thickness of the pre-filter layer is greater than or equal to 0.1 mm;
the second layer has a basis weight of greater than or equal to 0.5 g/m 2 and less than or equal to 10 g/m 2 ; and
the filter media further comprises a third layer and a fourth layer.
19. The filter media as in claim 1 , wherein:
the filter media further comprises a third layer and a fourth layer;
the filter media has a basis weight of greater than or equal to 60 g/m 2 and less than or equal to 150 g/m 2 ; and
the filter media has a thickness of greater than or equal to 0.1 mm and less than or equal to 2 mm.
20. The filter media as in claim 1 , wherein:
the first fibers and second fibers comprise continuous fibers;
the first fibers comprise synthetic fibers having a median fiber diameter of greater than or equal to 1 micron and less than or equal to 2 microns;
wherein the median fiber diameter of the second fibers is less than or equal to about 0.5 microns; and
wherein the median fiber diameter of the first fibers is greater than the median fiber diameter of the second fibers.