Plasma table recommendations for air drier system

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03 Aug 2017 01:16 #96953 by kb8wmc
kb8wmc created the topic: Plasma table recommendations for air drier system
Looking for suggestions for either DIY or OEM air drying systems for plasma machine using Hypertherm 45 ?

Second question: What is the preferred method for grounding the material to be cut? Is it advisable to use the bed grate to attach a grounding clamp or directly to material to be cut?
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03 Aug 2017 04:04 #96959 by islander261
islander261 replied the topic: Plasma table recommendations for air drier system
Hello

The method(s) you use for air drying depend on the temperature and relative humidity of the air supply to your compressor. My compressor and table are 100m from the sea in a cool wet climate. I have an automatic drain valve on the compressor receiver, cooling loop with drain legs out of copper tubing, usual air filter separator, refrigerated air dryer and desiccant air dryer. I get no moisture or oil in the filter on the plasma power supply. This is massive over kill if you don't live in hot humid place.

You should have a star ground point on your table chassis that the work lead from your plasma power supply is connected to. This point should have a lead that connects to your slats and a lead that has a clamp to attach to your work piece. Optionally if you have a table earth grounding rod it should also connect to the star point.

John
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03 Aug 2017 08:30 #96965 by rodw
rodw replied the topic: Plasma table recommendations for air drier system
Here's what I've done (still to mount up) with a similar sized Everlast 50 amp plasma


I purchased the silver 3 stage filter from eBay: Filter/Regulator, Coalescing filter, dessicant module. Finally, a Motorguard "toilet roll" filter which I see on just about every plasma cutter in service. I got it here www.machineryhouse.com.au/C492 where it is sold as a plasma filter. I am currently testing my machine and am using a cheap direct drive compressor because the table is too far away from my workshop to use my belt driven compressor. I will say the air is very wet and I'm pleased I have the dessicant as it changed colour slightly on the first test run. I would not use one of these compressors.
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03 Aug 2017 08:42 #96968 by tecno
tecno replied the topic: Plasma table recommendations for air drier system
Very interesting "toilet roll" filter, never seen this type of filter before.

Now added to my wish list for future plasma table build. Have been collecting parts for a while, problem I have is lack of space so I will have to build this modular so it can be setup when needed.
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31 Aug 2017 12:54 #98281 by robertspark
robertspark replied the topic: Plasma table recommendations for air drier system
Hello, (first post over here)

I started off with a 25L, 2.5HP (reportedly 9cfm) reciprocating direct drive compressor.

I've tried a few setups over the past few years, first being simple "cheap" oil filter with a secondary paper filter 5micron I think it was at the plasma cutter intake.

I then upgraded to adding a length of copper pipe between the compressor and the receiver to provide a little extra cooling to remove some of the moisture. [note I did sandblasting too]

Because of the sand blasting, I added a second 50L, 3HP (reportedly 15CFM) [twin Vee design] reciprocating direct drive compressor, which I run in parallel.

My length of copper tube then became a lot longer and ended up being dumped in a bucket of cold tap water (about 4-10ÂșC in the UK summer- winter]) to provide a bit of extra moisture removal (you can add ice to the bucket as others have tried).

When I got the Hypertherm 45 (upgrade from an older PMX 350), I decided time to improve things and looked at better filtration, lower pressure loss (given multi stage filtration can add a lot of pressure loss to a system [just try to blow through a multistage filter arrangement]) and given I still do some sand blasting (another forum + story) I looked at options to improve my pipeline arrangement, installing a refrigerated compressed air cooler, replacing my 2 compressors with a hydrovane (or similar alternative), desiccant dryer, or fabricating one, until I came across a membrane dryer, which I'd never considered before.

I'll post some pictures up later, but my current setup is:
2 belt driven compressors in parallel, each with a VFD, with a 1:1 belt drive, running at 900-1500rpm. Admittedly I've not finished the PID control of the VFD yet (another forum + discussion) as I was aiming for a lower noise solution.

3 stage filtration (Hiross type) Q, P & S (see page 8/12 of the below PDF for filtration details)
www.airsupply.co.uk/wp-content/themes/l3...inginlinefilters.pdf
www.aliexpress.com/item/High-quality-oil...s.9042311.0.0.5BPLFq
The theory is, larger surface area, lower pressure loss relative to my flow demands, plus longer time between filter changes required with new cartridges only.

Manifold arrangement, with primary low pressure loss (3/4") regulator & secondary regulator (compressed air fed blast mask), with breathing air filter.
With a few PCL XF low pressure loss quick connectors [eq. rectus 25/26; legris 25/26; cejn 320; norgen 234/238 or shrader intercheck 35)

membrane dryer (Sharpe 1-6770-3) [just the membrane dryer, not the regulator / other filters]
www.graco.com/content/dam/graco/tech_doc...0/310596/310596J.pdf

Membrane dryer offers the advantage of being maintenance free (providing filters are doing their job), and offering good moisture removal, lower the demand, lower the moisture content of the air delivered. Disadvantage.... they require a purge air supply hence when running always bleed air.

I probably went a "bit" overboard but I can finally say I have clean dry air I'm happy to breathe in and also use for plasma + sandblasting is sufficient quantities for a pressure pot blaster to get good duty cycle and lower noise.

I have still to make a better air intake silencer, but have an idea about making one similar to a suppressor using various cavities and some sound deadening material + copper pipe.


In the end I was not keen on a desiccant dryer (which I was looking to fab up from tube and desiccant) because most of the desiccant is silica beads. especially with the potential for silicosis if using it for breathing air I believe may be a potential issue. Also the blue beads are suppose to be toxic (cancer causing) I believe because they use cobalt-chloride and are supposed to be band is some countries now:
en.wikipedia.org/wiki/Silica_gel
brownell.co.uk/blue-indicating-silica-gel.html
www.isconline.com/assets/Image/Product/specs/GL_GDD_CutSpec.jpg
4.bp.blogspot.com/-hloY0EWUPpE/U6PJ-2Nf6...+dessicant+dryer.jpg

There is a bit on drying and filtering air here + options if you are interested:
www.powdercoatguide.com/2014/06/how-to-d...ed.html#.WagG4D6GPRZ
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31 Aug 2017 13:07 #98282 by rodw
rodw replied the topic: Plasma table recommendations for air drier system
Robert, thanks for this, very interesting. Glad to see you here :)
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