Re: [OT] material for hose and seals on desolder gun

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On Monday, February 3rd, 2025 at 5:07 AM, Spehro Pefhany <[email protected]> wrote:

> Hi, mad:-
> 
> I replaced the vacuum hose on my Pace station with pinkish polyurethane lawnmower fuel line from a big box hardware store. No problems- typical PVC is too soft. Silicone is better for heat resistance in case an iron touches it but also probably too soft.
> 
> Depending on the diameter you might find suitable PU pneumatic hose from AliExpress. Their fuel line seem to be yellowish.
> 
> Best regards,
> Spehro Pefhany
> 
> > On Feb 2, 2025, at 8:42 PM, madscientistatlarge [email protected] wrote:
> > 
> > I ask here because I suspect several people know this. What's the best tubing/O-ring material for handling desoldering fumes for all the "common" fluxes used in electronics? Natural butyl rubber, silicone rubber, FKM, etc? All ready worn out trying to find fittings on aliexpress. They really need to improve the search function.
> > 
> > Still deciding whether to use NPT,BSP or metric plumbing. Looks like BSP is the easiest to find. To clarify, the desolder station provides the vacuum suction. The compressed air part is easy. Planning to use a venturi and a compressor for durability and because I could use an air compressor for lots and lots of other things! Diaphragm pumps have a short life, especially with brushed motors but even with brushless motors. I Really, Really wish the U.S. would go metric, the imperial system stinks in many, many ways.
> > 
> > Yes, I"m working on my nearly universal solder/desolder station design. It'll even handle 400-500Khz irons, up to 300 W. It will make it easy to use for inductive heating for the more complicated jobs.

Thank you.  Actually I probably will use silicone rubber.  It's available for "vacuum lines" in cars.  6mm id, 12mm od for vacuum line, much thiner for other apps.  

Good to know polyurethane worked for you, I'll use it for the internal plumbing.  It's very popular for pneumatic use with a lot of nice fittings on aliexpress.  Stiffer, but the lines are all short and I'll try to arrange the plumbing to avoid unnecessary bends in any case especially on the vacuum part.  I've worked on ultra-high vacuum systems before (this is "course" vacuum, not really close to what ultra high vacuum systems need, conduction (fluid/gas) is very important at reduced pressures).  The energy demand for pumping is proportional to the difference in pressure so wasting vacuum has a real cost (i.e. larger pumps etc.)  There's always back diffusion so a very small amount of the old flux fumes will get everywhere in the system.  It's nice if the system doesn't require constant maintenance.  I prefer working with tech to working on getting tech working again.  I couldn't find anything on the web so I figured it wasn't too difficult.  The gun comes with 3mm id vacuum hose so 1/4" (6-7mm) should work very nicely, especially with a 2M hose.

Also, I live at about 5000' feet, so instead of the 15PSI at see level the air pressure is only about 12PSI to start with.  I.E. the vacuum for the gun is higher.  Water boils at a lower temp, and it's best to modify backing recipes for say brownies.  For those I use a couple of teaspoon fulls of water, and very slightly cooler and longer baking.  It's a small effect, baking recipes are very hard to play with, they go bad rather easily when tampered with. 

So, silicone rubber it is.  I was also going to put an antistatic cotton sleeve over it (availahle on aliexpress etc.).  It's mildy static dissipative (and won't be hurt that much from brief contact with the hot stuff).

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