Plastic support net for filter media

1. A filter assembly for removing particulate matter from a fluid stream, the filter assembly comprising:

a filter medium having a number of longitudinally extending spaced pleats, wherein opposing faces of adjacent pleats form a valley therebetween and include a pair of peak portions and a valley portion; and

a plastic support net being pleated for supporting the filter medium in a pleated shape,

the plastic support net including spaced strands extending in a first direction and spaced strands extending in a second direction generally transverse to the first direction, the spaced strands extending in the first direction continuously extending over the valley and peak portions of opposing faces of adjacent filter medium pleats and being aligned in a direction generally perpendicular to the longitudinal direction of the filter medium pleats, and the plastic support net being formed of a plastic material capable of being pleated into a pleated shape at an ambient temperature and substantially holding the pleated shape after the ambient pleating operation.

2. The filter assembly of claim 1 , wherein the plastic support net forms a continuous space for flowing a fluid stream and bounded by the pair of peak portions and the valley portion.

3. The filter assembly of claim 2 , wherein the plastic material is substantially comprised of a high-density polyethylene (HDPE) plastic material.

4. The filter assembly of claim 1 , wherein the plastic support net is comprised of an extruded plastic net oriented in the second direction.

5. The filter assembly of claim 4 , wherein the ratio of the weight of the strands extending in the first direction to the total weight of the plastic support net is in the range of 0.51 to 0.85.

6. The filter assembly of claim 1 , wherein the filter medium is susceptible to heat damage upon heating the filter medium to a temperature of 120° F. or greater.

7. The filter assembly of claim 1 , wherein the pleated shape of the plastic support net is adapted to mechanically hold the pleated shape of the filter medium without chemically bonding between the plastic support net and the filter medium or between the spaced strands in the second direction of adjacent plastic support net pleats.

8. The filter assembly of claim 1 , wherein the plastic net is coupled to the pleated filter medium with an adhesive.

9. The filter assembly of claim 1 , wherein the plastic support net is comprised of a woven plastic net, the strands extending in the first direction and the strands extending in the second direction are comprised of plastic monofilaments.

10. The filter assembly of claim 1 , wherein the thickness of the strands extending in the second direction is in the range of 1 to 50 mils and the thickness of the strands extending in the first direction is in the range of 3 to 125 mils.

11. The filter assembly of claim 1 , wherein the plastic support net is comprised of an extruded plastic net oriented in the first and second directions.

12. A plastic support net for supporting a filter medium having a number of longitudinally extending pleats, opposing faces of adjacent pleats forming a valley therebetween, and including a pair of peak portions and a valley portion, the plastic support net comprising:

spaced strands extending in a first direction and spaced strands extending in a second direction generally transverse to the first direction bonded to the spaced strands extending in the first direction, the strands extending in the first direction continuously extending over the valley and peak portions of opposing faces of adjacent filter medium pleats and being aligned in a direction generally perpendicular to the longitudinal direction of the filter medium pleats, the plastic support net being pleated for supporting the pleated filter medium in a pleated shape, and the plastic support net being formed of a plastic material capable of being pleated into a pleated shape at an ambient temperature and substantially holding the pleated shape after the ambient pleating operation.

13. The plastic support net of claim 12 , wherein the plastic support net forms a continuous space for flowing a fluid stream and bounded by the pair of peak portions and the valley portion.

14. The plastic support net of claim 13 , wherein the plastic material is substantially comprised of a high-density polyethylene (HDPE) plastic material.

15. The plastic support net of claim 14 , wherein the plastic support net is comprised of an extruded plastic net oriented in the second direction.

16. The plastic support net of claim 15 , wherein the plastic support net has a strength to weight ratio of 0.5 to 2.0 lbf/(in*PMSF).

17. The plastic support net of claim 16 , wherein the ratio of the weight of the strands extending in the first direction to the total weight of the plastic support net is in the range of 0.51 to 0.85.

18. The plastic support net of claim 12 , wherein the plastic support net is comprised of a woven plastic net, the strands extending in the first direction and the strands extending in the second direction are each comprised of plastic monofilaments, wherein the unit weight of the strands extending in the first direction is heavier than the unit weight of the strands extending in the second direction.

19. The plastic support net of claim 12 , the plastic support net is comprised of an extruded plastic net oriented in the first and second directions.

20. A method for forming a pleated filter assembly, the method comprising of:

providing a generally planar plastic net adjacent to a generally planar filter medium to obtain a generally planar filter assembly; and

pleating the generally planar filter assembly at an ambient temperature to obtain a pleated filter assembly including a pleated filter medium for removing particulate matter from a fluid stream and having pleats extending in a longitudinal direction and a direction generally perpendicular to the longitudinal direction and a pleated plastic support net for holding the pleated filter medium in a pleated shape after the ambient temperature pleating operation.

21. The method of claim 20 , wherein the ambient temperature is in the range of 50 to 100° F.

22. The method of claim 20 , wherein the pleated plastic support net is made of a HDPE material.

23. The method of claim 20 , further comprising:

providing an extruded plastic net having an interconnecting network of machine direction (MD) strands and cross direction (CD) strands that extend transversely to the MD strands; and

orienting the extruded plastic net in the CD to obtain an oriented, extruded plastic net for use as the generally planar plastic net and having relatively thick MD strands and relatively thin CD strands, and

wherein the providing step comprises:

aligning the oriented, extruded plastic net with the generally planar filter medium such that the relatively thick MD strands run along the generally perpendicular direction of the pleated filter medium after the pleating step.