Just pressurize with nitrogen before opening the system, and continue to purge N until its closed back up. No way moisture can get in there if you do it that way.
The process of heating dessicant as a means of driving moisture out of it is called reactivation.
Having worked at the valve company in question.....reactivating cores is possible....but not practical.
Sporlan's recommendation is 500F for 4 hours for the standard or high water cores (450F for the HH core). So, a heat gun isn't going to offer any significant reactivation.
It would be completely impractical to reactivate a sealed model filter-drier, as the paint would be destroyed.
Core driers are easier to navigate in an oven, but after reactivation the filter-drier would still contain any dirt/debris it had filtered out of the system plus any acid that had been removed would still remain.
In addition, any oil contained in the filter-drier would decompose at those temperatures.
Open the system....replace the filter-drier.
That's another cause for discussion sporlan literature speaks of HH driers basically for removal of parafin wax as in lowtemp 404 retrofits but I hear guys talk about using them after a burnout regardless of application. I always acid test when Im unsure of the service history or a system has sat flat for awhile on a positive acid test is there any benefit to using HH style liquid line drier even on AC ( non- low temp) applications? also who is bob and why will he be my uncle?
The standard core has a higher acid capacity then the HH core...but not by much.
The HH core was developed to remove wax like contaminants (not parifin) in LT R-22 and R-502 systems. It's not an issue with R-404a.
It turns out that the activated carbon does a much better job at removing decomposed oil from motor burns than the standard core does, so that's why it's recommended for burnout situations. Also R-22 systems that have operated with high discharge temperatures, resulting in oil decomposition.
The suction filter-driers are mostly used after a burnout, which is why they are made with the HH core.
Good to hear it!
Originally Posted by bunny
When I was younger and had more energy, I would cut out all sweat driers for fear of releasing moisture by using a torch. Then a point in time came when I realized it was unlikely there would be enough moisture in there to make a difference anyway. That was before POE oil. But I've still been using a torch to unsweat the driers. I just take care to keep the flame off of the body of the drier.
You've just confirmed how hard it is to release that moisture once it is caught in the desiccant.
I know it's hard to imagine - but we are trending Way off the original subject. <g>
The situation is:
1. There is a freshly worked on system. It had a precautionary LL drier installed by a meticulous and well-trained refrigeration mechanic. Justin Case there was a particle of dirt or grain of moisture which had escaped the mechanic's scrupulous working and dehydrating protocol.
2. There was then subsequent cause to re-open the already re-started and operating system.
Question: Do you all think it would be OK to just leave the just-replaced existing LL drier in place, re-prep the system, and re-start it?
My opinion is: yes. <g>
And my logic is: the original drier very likely contained little to nothing. The replacement drier almost certainly contained nothing. Let's not act as though most driers are somehow saturated with moisture and nearly clogged - they aren't. The vast majority of LL driers go in clean and dry and remain clean and dry until the system fails and/or is replaced. <g>
The conventional view serves to protect us from the painful job of thinking.
Originally Posted by duckman373
^^My thoughts align EXACTLY with PHM up there.
I totally agree that to open again for minor repair and replace new dryer is pointless and waste of time. As far as the HH driers and 404 I was referring to retrofit scenerios and the fact that the wax from low temp min oil would normally lay dormant but the POE has a detergent effect and that's where the HH style come in. It's the acid / contaminant clean up in a liquid line HH dryer I'm questioning