Putting a Filter after the cascade?

[rjack321]

BTW a small LF chamber is rated for 13,000cf. That's about 72 hrs of runtime on a W31 (3 cfm).

 

[oxyhacker]

Yes but that's at 5000 psi (!) and 80 degree inlet temperature. Going from 5000 psi to 3000 psi just about cuts in in half, as does going increasing the inlet temperature from 89 to 100, so in real life one would easily see only a 1/4 of that, or even less.

Re the subject of this thread, though, putting a filter after the cascade seems sort of like putting your dirty dishes away in the cupboard after eating, and not washing them until you get them down to set the table for the next meal.

BTW a small LF chamber is rated for 13,000cf. That's about 72 hrs of runtime on a W31 (3 cfm).

 

[JBRES1]

Vance,
Sounds like you were in the same frat house as I was. We solved the dirty dish problem by making everybody take their plates back to their room. Either you clean your plate or you eat off of a dirty plate. God do I miss those days , not a care in the world except when the next ball game was or the next party , or both.

As for this thread, I was looking to see if a final filter was a good thing or not.
It looks as if I will be going with the original plan of a second filter after the Airetex
standard filter.

Thanks , Jim breslin

 

[rjack321]

Yes but that's at 5000 psi (!) and 80 degree inlet temperature. Going from 5000 psi to 3000 psi just about cuts in in half, as does going increasing the inlet temperature from 89 to 100, so in real life one would easily see only a 1/4 of that, or even less.

Its impossible to know since the stock P0 filter on the Alkins is supplying the small LF tower with <24ppm water vapor already. So the second filter is not working very hard; the little moisture sensing strip has never even started turning pink. The 13x in my final filter is definately not saturated. Since there's no way to measure the vapors trapped by the AC, I change it at approximately the rated capacity. Seems to be working fine. The couple times I've sent gas in for analysis its always been with OCA limits.

Max temp I've ever pumped is maybe 85F (ambient). Most (80%) of my hours are 70F or way less. Like tonight, it was 42F.

 

[pescador775]

Yes but that's at 5000 psi (!) and 80 degree inlet temperature. Going from 5000 psi to 3000 psi just about cuts in in half, as does going increasing the inlet temperature from 89 to 100, so in real life one would easily see only a 1/4 of that, or even less.

Is the LF unit a filter or hybrid filter/separator? I believe I heard that it is the latter. Regardless, I am curious as to under what theory the water separation/adsorbtion rises at higher pressure and drops at lower pressure. Based on physics, a good argument can be made for separator efficiency increasing at higher pressure. Is this the gist of the matter? I ask because it is not clear if it is being implied that dessicant is more efficient at high pressure. It may be that this is the case but the increase in so called dwell time would have only a small effect when employing a chemical which filters by counting (intercepting) molecules which pass through it. Moreover, it is not clear how this would impact the overall water capacity of the dessicant. I doubt that pressure would have any effect. Molecular seive is preferred for high pressure systems because it is not adversely affected by pressure as is the case for some other dessicants. However, its total capacity is also not reduced by low pressures. What exactly are you referring to in that quote?
Pesky

 

[pescador775]

I have a follow up question (anybody). Where is the documentation, the experiments, which say that dwell increases the efficiency or capacity of seive? I have heard these claims from various people but they can be traced only as far as Global or somebody else who is selling equipment. You know, I did the experiments and calcs which indicated that "dwell" would increase the uptake of water by seive. However, considering that the average filter cartridge has only about a cubic inch of air space I opined that the uptake of water at high pressure would increase the adsorption solely due to dwell from "virtually nothing" to "next to nothing". However, I also said when looking at very large cartridge or canister volume that dwell would make some difference, possibly enough to say "significant" in the case of a wall hanger sized can being served by a small compressor.

 

[rjack321]

I have not heard that dwell time increases filtration. Doesn't really make sense to me. More media sure, but unless the rate of flow is very large I doubt it makes much difference. Having a small filter after some big banks and letting the gas rip through at the max rate 1/4" or 3/8" tube can handle it might have the affect of so shortening dwell time that the gas is incompletely filtered (or channeled its way through the media)