Originally Posted By: ZeeOSix
Prove otherwise.
Prove you're not.
Prove otherwise.
Prove you're not.
Purolator Classic p14610 NEW - Ripped opened
- Thread starter garlicbreadman
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The OP reported that a Classic tore very easily. That's interesting.
Also note how virtually all of the pleats are double strength based on how flat they are folded when glued. You can see that if pressure was applied to any part of those flat pleats, it would flex very little. But it would flex.
The pleats next to the metal crimp are single walled and stiff. They can't flex like the double walled pleats. Continual pressure is far more likely to stress the pleat at the point it flexes the LEAST ie near the strong glue at the end caps. And being single walled, it can't resist as much as the folded pleats.
When the V is more pronounced and when the gap either side of it is larger, it will flow more oil than other pleats. One because there is a larger volume of oil but more importantly, remember what I said about flat pleats being doubled walled vs the V pleat being singled wall? That means that the oils least path of resistance is through the V pleats. So the weakest structure gets the most oil pushing against it.
In fact, in cases where the V and gaps with adjacent pleats is most pronounced, the other pleats are even more flat, double walled and stronger with the V even more brittle.
Variations of the same filter would explain why we see some issues and some ok in the same filter.
I think this mechanism has not been mentioned before ie greater flow through the V compared to other pleats.
Some pretty good observations. Yes, that "V" pleat itself indeed will have to handle a larger portion of flow, and, a greater overall pressure load (pressure load net effect is radially inward, toward the center tube).
As to double vs single wall. What you are missing is that, the walls support each other against the pressure, when they are "flat" folded against each other. They basically cant deflect from pressure, in a tangential direction (perpendicular to radial direction). The "V" configuration allows the individual plies of paper to experience substantial tension from fluid pressure (kinda like lifting a dumbbell with a piece of tape). Also note, the net pressure load (unbalanced by opposing pleat pressure load) is inward, as mentioned above.
Now keep that in mind, and realize there is far less "line length" of media per unit area projected onto the center tube. That is, normally there are say 3 pleats, 6 sheets, of media when densely packed, now there is 1 pleat, 2 sheets. You just cut your strength by a factor of 3. In shear, primarily. You also take away the "beam-like" character of the pleat arrangement - the media will experience more tension from bending forces.
Another way to think of this is, what happens when the "V" spreads out to be almost flat. Now, the media is purely in tension, against potentially many pounds of pressure force. If youve ever tried to pull on a taught strung wire/rope/string, perpendicular to its direction, you might have realized that a small load in that direction can generate a huge tension in the rope direction. In this analogy, the plies of media, are like the rope.
You are right to point out the stress concentration near the glue. That will be a point of maximum bending stress, and also represents a relative material and stress discontinuity, which largely explains why it is the typical point of failure.
Not the cleanest explanation, but hopefully you get the basics of why this defective construction is leading to media tearing (FAILURE).
As to double vs single wall. What you are missing is that, the walls support each other against the pressure, when they are "flat" folded against each other. They basically cant deflect from pressure, in a tangential direction (perpendicular to radial direction). The "V" configuration allows the individual plies of paper to experience substantial tension from fluid pressure (kinda like lifting a dumbbell with a piece of tape). Also note, the net pressure load (unbalanced by opposing pleat pressure load) is inward, as mentioned above.
Now keep that in mind, and realize there is far less "line length" of media per unit area projected onto the center tube. That is, normally there are say 3 pleats, 6 sheets, of media when densely packed, now there is 1 pleat, 2 sheets. You just cut your strength by a factor of 3. In shear, primarily. You also take away the "beam-like" character of the pleat arrangement - the media will experience more tension from bending forces.
Another way to think of this is, what happens when the "V" spreads out to be almost flat. Now, the media is purely in tension, against potentially many pounds of pressure force. If youve ever tried to pull on a taught strung wire/rope/string, perpendicular to its direction, you might have realized that a small load in that direction can generate a huge tension in the rope direction. In this analogy, the plies of media, are like the rope.
You are right to point out the stress concentration near the glue. That will be a point of maximum bending stress, and also represents a relative material and stress discontinuity, which largely explains why it is the typical point of failure.
Not the cleanest explanation, but hopefully you get the basics of why this defective construction is leading to media tearing (FAILURE).
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