HF Filter pressure drop

[Odyknuck]

I recently purchased a Harbor Frieght Descicant filter for my SC50P. Now I get a 25 PSI pressure drop. I am getting old so I do not recall what the pressure drop was before I added the HF Filter. Has any one experienced this? My Compressor is 5 HP 80gal tank so it is definatly not a supply pressure issue. On the SC50P I have an Inline water seperator then the Regulator (comes with the unit) set to 60 PSI currentlyand then the HF filter.

[redbeard]

It is normal to have some drop when you start drawing air through the regulator, but 25psi sounds a bit excessive. Are you setting the regulator while the air is flowing? That way you get the proper dynamic pressure.

You might also pull the dryer out just for the process of elimination.

[Odyknuck]

Granted you will have a dynamic pressure drop however I believe is was less than 10 before the filter. Removing the filter is the mext step. I posted to see if anyone else has used this particular filter with better sucess than mine.

[Rambozo]

Granted you will have a dynamic pressure drop however I believe is was less than 10 before the filter. Removing the filter is the mext step. I posted to see if anyone else has used this particular filter with better sucess than mine.

You can always parallel a couple of them to get more flow, and less pressure drop.

[redbeard]

Granted you will have a dynamic pressure drop however I believe is was less than 10 before the filter. Removing the filter is the mext step. I posted to see if anyone else has used this particular filter with better sucess than mine.

I installed mine this evening and can confirm your results, HUGE loss of pressure once it was in line. Looking in from the outside, it looks like there is a stone type filter at the inlet, and packed cotton or felt disks at each end of the dessicant, maybe replacing those with something that breathes easier will help.

You can always parallel a couple of them to get more flow, and less pressure drop.

Good idea, but even with tubing and compression fittings that sounds like a wee bit of a PITA. I'd almost rather splurge on a Motorguard before doing that.

[Odyknuck]

Thanks for the confirmation Redbeard, now we know for sure it's not just the one I have. Curious if the other small inline filters have a similar pressure drop. I may go with the motorguard too. I really wanted to keep the package small and local to the Plasma cutter.

Rambozo, even with two in parallel you would still get about 12 PSI drop.

[redbeard]

Solved! It is the filter that is pressed into the inlet side that is the problem. Just take it apart and tap it out using something thin and stiff for a punch.

It is kind of surprising how little dessicant there is in there, we will probably wind up recharging/refilling these things fairly frequently.

[Rambozo]

Solved! It is the filter that is pressed into the inlet side that is the problem. Just take it apart and tap it out using something thin and stiff for a punch.

It is kind of surprising how little dessicant there is in there, we will probably wind up recharging/refilling these things fairly frequently.

I bet that "filter" is made to slow the flow of air for the amount of desiccant that is there. I wonder what the formula is for airflow vs surface area of desiccant and moisture removed? Whatever it is, you can bet that good old HF performs like only they can. I like the idea, others have mentioned, of building a dryer from a large filter housing or pressure vessel. Better drying, with less pressure drop, and longer media life.

[Odyknuck]

Cool, good call. I suspect these were originally designed for paint spray guns that do not need a high CFM rate so the pressure drop is not a big factor.

Solved! It is the filter that is pressed into the inlet side that is the problem. Just take it apart and tap it out using something thin and stiff for a punch.

It is kind of surprising how little dessicant there is in there, we will probably wind up recharging/refilling these things fairly frequently.

[Odyknuck]

I bet that "filter" is made to slow the flow of air for the amount of desiccant that is there. I wonder what the formula is for airflow vs surface area of desiccant and moisture removed? Whatever it is, you can bet that good old HF performs like only they can. I like the idea, others have mentioned, of building a dryer from a large filter housing or pressure vessel. Better drying, with less pressure drop, and longer media life.

Good possibility. I am curious what the pressure drop from the other manufactures are.

[redbeard]

I bet that "filter" is made to slow the flow of air for the amount of desiccant that is there. I wonder what the formula is for airflow vs surface area of desiccant and moisture removed? Whatever it is, you can bet that good old HF performs like only they can. I like the idea, others have mentioned, of building a dryer from a large filter housing or pressure vessel. Better drying, with less pressure drop, and longer media life.

HF used to sell a big wall mounted unit that looked like it was just 1-1/4 or 1-1/2 pipe with side ports welded on and plugs or caps at each end to change the pellets. Building one like that should be simple enough, I'm just trying to figure a way to have a couple window slots in it; I guess a person could just use the small one at the machine as an indicator for changing the big one, but where is the over-engineering challenge in that?

[Rambozo]

Building one like that should be simple enough, I'm just trying to figure a way to have a couple window slots in it; I guess a person could just use the small one at the machine as an indicator for changing the big one, but where is the over-engineering challenge in that?

You can get pipe plugs with a sight glass in them.

[GWD]

I recently purchased a Harbor Frieght Descicant filter for my SC50P. Now I get a 25 PSI pressure drop. I am getting old so I do not recall what the pressure drop was before I added the HF Filter. Has any one experienced this? My Compressor is 5 HP 80gal tank so it is definatly not a supply pressure issue. On the SC50P I have an Inline water seperator then the Regulator (comes with the unit) set to 60 PSI currentlyand then the HF filter.

Definitely not the correct application for those small filters. They are made for paint spray guns as has already been mentioned. With the volume of air necessary for a plasma cutter it doesn't seem likely that they will stop much of the moisture.

I tried the small HF ones and some other manufacturers but they all had the same result - way low pressure when the torch is lit.

HF used to sell a big wall mounted unit that looked like it was just 1-1/4 or 1-1/2 pipe with side ports welded on and plugs or caps at each end to change the pellets. Building one like that should be simple enough, I'm just trying to figure a way to have a couple window slots in it; I guess a person could just use the small one at the machine as an indicator for changing the big one, but where is the over-engineering challenge in that?

Too bad they discontinued that model. I was able to buy one and also bought some extra desiccant pellets to switch them out while the other set dries. You could make your own filter with some metal screening with a circular and drilled supports to keep the pellets out of the air line. Bulk pellets are available from several places online.

An impact wrench and the correct socket makes it easy to check the condition of the desiccant. A sight glass would be easier however.

Pressure drop is negligible with the large pipe-style tank.

[acourtjester]

May I suggest using a home water filter like attached and fill it with desiccant. You will be able to see the color change and the volume of air should be just fine for plasma. I comes apart easy for desiccant refurb, just remember to use the standard filter for these units to stop and desiccant dust from passing through to the torch. As the attached shows it is rated a 125PSI. Can be found at Lowes & Home Depot and other places.

[redbeard]

This is my primary dryer at the moment:



This is the HF unit in pieces:



Not enough in there to dry much air at all. It will go back on as a secondary though.

[Odyknuck]

I removed the filter and it does make a difference. I have a typical glass oil/water seperator ahead of the regulator that I am going to fill with desicant. It will probably hold 10 time the amount in the HF filter. I ordered a pound of dessicant for 17 bucks shipped.