Mark,
I am very interested in your use of the pancake compressor. Would you please give us more info on where and how you have it hooked up? Especially your plumbing of it.
Thanks,
Trent
Mark,
X2.
Thanks
I carry a Porter Cable 150psi pancake compressor, but I only use it for inflating tires, winterization, and filling inflatables for the lake.
I did have an air dryer failure once, where it was stuck purging. I made it off the road and into a U Haul facility, where they helped me with a few spare air fittings to make a male-male adapter and backfeed air from my porter cable compressor into the RV hose built into my stair bay. This made enough air to get me back home and leisurely purchase a reman dryer from napa and install it. Everything worked well and I always carry the compressor, adapter, large air dryer, Milton tire filler with 8ft whip and Haltec tire valve clip on the end so you can safely fill tires from far away.
Add me to Tulsa Trent's comment. Sounds like a project to me.
Compare the SCFM rating before you buy, the cheapies from China will make a lot of noise and take a long time to air up your coach.
A lot of these give a SCFM rating at 0 psi, this is irrelevant. The SCFM rating at 100 psi is the one that matters.
As a point of reference, the 12V compressor I used would air up to 120 psi from 60 psi in about 6 minutes (my typical pressure after camping overnight).
Using a pancake air compressor unless fitted with a dryer will induce water into the air system
I looked up the 120V compressor I'm using. I bought it on sale at Home Depot for $109. It's rated at 2.6 SCFM @ 90 PSI and has a max pressure of 150 PSI.
Porter-Cable 6 Gal. 150 PSI Portable Air Compressor-C2002 - The Home Depot (http://www.homedepot.com/p/Porter-Cable-6-Gal-150-PSI-Portable-Air-Compressor-C2002/203162815)
I clicked on Mark's link, which took me to Home Depot's site for $129. My price catcher pulled up a link from Amazon, for $89, with free shipping!
htpp:://www.amazon.com/dp/B000O5RO1Y (http://www.amazon.com/dp/B000O5RO1Y)
Thanks, Mark; now, about that air plumbing information . . .
Trent
Here's as basic flow chart. In our coach the magic is in the aux drying system that's now installed. The OEM drying system was completely trashed when we bought this coach. We replaced most of it with a multi stage drying system from ATD Tools:
ATD-7763 - 5-Stage Desiccant Air Drying System - ATD Tools, Inc. (http://atdtools.com/7763)
The output of both compressors feed the input of the ADT dryer. The output of the ATD dryer feeds the input of the OEM desiccant filter (which really isn't needed since the ATD has a desiccant filter, but it was a hassle to take it out. Maybe someday).
I have the regulated output of the Porter Cable 120V compressor set to ~125 PSI. The pressure switch high cut-off for the Thomas 12V compressor set to about 80 PSI and the low cut-in set to about 60 PSI. Thus if the Porter Cable 120V compressor is supplying air there's no call for air from the Thomas 12V compressor. If the Porter Cable 120V is off, the Thomas 12V compressor will kick in when the aux air drops below about 60 PSI.
The following applies only to the 2003 U320 air system and I do not know how other model's air systems are plumbed.
Regarding the main air system, the front and rear OEM air tanks are each equipped with an OEM protection valve. These protection valves will supply air to the leveling system as long as the front and rear tanks are above the value at which the protection valve opens. I believe the OEM protection valves open at a nominal value of 75 PSI and close when the respective front or rear tank drops to 70 PSI. This protects the main air supply for the air brake system from complete depletion through contribution to the leveling system. Because of this contribution of air from the main tanks to the leveling system, there's no need for additional air from the aux air system when the main engine is running and the main air system is at normal pressure. There is one exception and that's slide-out operation. Air to deflate and inflate the slide-out bladders is only supplied by the aux air system. If all the system check valves are operating correctly there is no air contributed from the main tanks for the slide-out bladder processes.
Newbie Question, I thought it wasn't cool to use a compressor to add air to our coaches. Aren't you going to add moisture to the system. How are you adding the air into the system without water contamination.
John M.
Look closely at the posts-- routing the "auxiliary compressor" output through an air dryer makes it perfectly OK.
Mark,
Just got around to looking closely at your ATD dryer setup. Very clean and pro-looking installation! A few questions:
1. What did the ATD setup cost, and where did you buy it? Don't see any pricing in your link.
2. Is the desiccant material reusable (dry it out in the oven), or 1-time use and replace it?
3. What is the price/availability of the replaceable filters?
Chuck,
1. Bought it on eBay for ~$400 ATD Tools 7763D Lg Cap Air Desiccant Air Drying System (http://www.ebay.com/itm/ATD-Tools-7763D-Lg-Cap-Air-Desiccant-Air-Drying-System/191302027767?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649)
2. Reusable
3. Amazon ~$46 Amazon.com: ATD Tools 77631 Filter Change Repair Kit for 5-Stage Desiccant... (http://www.amazon.com/gp/product/B00J6C1WEG/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1)
Please let me know if you have any additional questions.
With that quality (and cost) of the ATD dryer, is there any benefit to retaining the OEM desiccant filter? Conceivably, it could already be compromised just based on its age.
I can see a redundancy benefit of the Thomas compressor, if adding a new pancake compressor. I wonder if that redundancy is really necessary? As some of our systems get older, I see a benefit to replacing with new or better systems. I do see some benefits of keeping the 12 volt compressor, but wonder if it is really necessary?
Thanks for any thoughts y'all are willing to share with my virtual design thoughts,
Trent
I think not. At the time I removed the OEM drying system and installed the ATD, I didn't have the needed items to fabricate a bracket to hold the pressure gauge, check valve, unloader solenoid, etc. That's the only reason I left it in place. Because the air coming into it is theoretically dry and dust free, it's serving no purpose other than structural.
Since we plan to boondock, I like the flexibility of having aux air provided by either a 12V or 120V compressor.
That is a nice set up Mark... Not as upscale as the unit you installed, but I bought a single housing Devilbiss 3 stage Dessicant, Filter, Dryer for our aux compressor (no slides on our 99' U270) quite a while ago, but have yet to install (on the project list!). The reason I haven't done it yet (time being the other obstacle) is because the instructions specify having 30' feet of line between the compressor output and the unit. I am sure that is to give more time for the air to cool to condense moisture. I haven't decided how (or if...) I am going to accommodate that requirement yet. What did your installation instructions say about where to place the unit in relation to the compressor output? The water separator on our coach was mounted next to the compressor (no desiccant stage on the U270), and I will keep that in the loop when I do this project.
Don
Edit: I should add that at this point, I don't have any plans to carry or add a 110AC pancake compressor to the coach system, though I will likely plumb in a place to hook one up before the dryer system. The ARB twin compressor that I replaced our Aux compressor with has enough oomph to raise the coach high enough to place the frame blocks without involving the engine compressor, as well as to inflate the tires. I won't use it for that until I install the new drying system though.
Here we go again...you guys have me thinking about another project (that will cost me money). I read about Don's super-duper 12V air compressor back when he first installed it, but didn't take the bait. One reason was because he complained a bit about the noise level. So then later I started carrying a cheap 110V compressor around in the coach, but haven't been entirely happy with that setup because it is also very noisy and does not have a air dryer, plus being a bit of effort to unload/load and carry around outside the coach.
Then Mark comes up with this idea of mounting a 110V compressor permanently and running the output through a filter/dryer before teeing it into the coach air system. This probably isn't a original idea - surely someone else on the Forum has done this - but I like his implementation. This is a idea I can get behind, except my existing portable compressor would be too noisy. It would drive me crazy. So I go Googling for a quiet 110V air compressor, and guess what; I found it!
A company called California Air Tools sells a whole line of quiet compressors. Watch the video linked below for a demonstration. It's amazing! I am thinking the 2010A model would be easy to fit into the storage bay (in the spot under the steps where the OEM inverter used to sit). I might run it through a filter setup like Mark's, then tee it into the tire filler hose line, so when it runs it would replenish the wet tank. That would keep the wet tank pressure (and the rest of the air system) between 90 and 120psi, which is pretty close to the normal coach air system operating range. Like Mark says, "Always ready to go.." It only draws 8-9 amps, so shouldn't be a problem running it on inverter when dry camping.
Gotta study some more on this, but it sounds like a fun project! 8)
https://www.youtube.com/watch?v=UDUXPyjz6UI
California Air Tools - The Largest Manufacture of Ultra Quiet, Oil-Free &... (http://www.californiaairtools.com/ultra-quiet-oil-free-air-compressors/1-0-hp-air-compressors/cat-2010a/)
California Air Tools CAT-2010A 1 HP 2 Gallon Ultra Quiet Aluminum Tank Air... (https://www.walmart.com/ip/California-Air-Tools-CAT-2010A-1-HP-2-Gallon-Ultra-Quiet-Aluminum-Tank-Air-Compressor/120856620?wmlspartner=wlpa&selectedSellerId=0&adid=22222222227043233667&wl0=&wl1=g&wl2=c&wl3=107559836597&wl4=pla-299761203677&wl5=9028611&wl6=&wl7=&wl8=&wl9=pla_with_promotion&wl10=8175035&wl11=online&wl12=120856620&wl13=&veh=sem)
I just reviewed the instructions and do not see any mention of line length between the compressor and the water trap (first stage in the dryer system). Fun idea though. Perhaps the easiest is to install a horizontally oriented coil of copper tubing line. It's readily available, easy to work with and conducts heat very well. It could be fastened to the ceiling of a basement compartment. And it could always double as part of a whiskey still if you don't need dry air at the moment!
Now
you're the one who's gonna cost me money. I didn't mention it before but the 120V compressor I have downstairs will wake the dead. It is LOUD. But, I only use it when working on the coach or getting ready to break camp.
Edit: Perhaps install just the California Air Tools motor and compressor since we have plenty of tanks:
California Air Tools SP-9413 1.0HP Ultra Quiet and Oil-Free Air Compressor... (https://www.amazon.com/California-Air-Tools-SP-9413-Compressor/dp/B00NGK4B0Q?th=1)
That is one of the options I thought of... but another forum member (can't remember who at the moment :o ) told me they did something similar and were disappointed that the cooling of the air was not that significant. But still, it would seemingly be one way to meet the recommended distance. One thing is for sure, even mounted close, a dryer would be a whole lot better than nothing for all the components which are downstream of the aux compressor!
Don
Best Quiet Air Compressors Reviewed.
Best Quiet Air Compressors (http://www.aircompressortalk.com/best-quiet-air-compressors/)
Remember that the dB loudness scale is a logarithmic scale. That means that a compressor that makes 70 db is twice as loud as one at 60 db. For each 10 db the sound level doubles.
The Porter Cable I now have makes 82 dB. It is a little more than 4 times louder than the 60 dB units Chuck found.
Just ordered the California Air tools compressor. Will do something like Mark's drier install.
Wow! No grass growing under your feet!
Good idea, except that you can buy the complete compressor unit from Walmart for less money. Then just cannibalize the parts you want to use, like the motor/compressor and regulator and switch + wiring. Save the tank for another project! :)) (there's
always another project)
Thinking about Don's question about achieving a long length of flow line between the compressor and the dryer, how about using a "universal" aluminum auto air conditioning condenser? That would give you a long flow length in a small space. You could mount it horizontal on the storage bay ceiling where it would be out of the way. Even have a small fan blowing through it if you wanted to get fancy...
I have considered that option, or rather a new old stock oil cooler that I happen to have from a Mazda R100 rotary engine... just unsure about the max psi these units can handle. I would like greater than 150 psi so that a 150 psi safety poppet valve would protect the system. I love the quiet compressor... I wonder if the 120 psi limitation is the tanks or the pump (or both). The 120 psi limitation would make filling the tires very tiresome :D
Don
A/C condenser will go over 200 psi. Junk yard item then pressure check.
Agree, if you are trying to fill a tire from empty. But if you are just adding a few psi to make up for seepage, then having the wet tank at 120psi should be adequate. I run our tires at 100psi, and I can use the coach air hose to top them off with 120psi in the wet tank - no problem.
The same company makes a somewhat less "quiet" 150psi compressor with twice the CFM flow rate, but it's kinda pricey:
California Air Tools SP-9421 2.0HP Ultra Quiet and Oil-Free Air Compressor... (https://www.amazon.com/California-Air-Tools-SP-9421-Compressor/dp/B00NGK47FK/ref=sr_1_18?srs=6769542011&ie=UTF8&qid=1500850348&sr=8-18&keywords=California+Air+Tools)
back to 70 db.
In case anyone might be interested, I found a good price on the DeVilbiss QC3 (see Don's post, reply #15) at Summit Racing:
DeVilbiss QC3 Filter and Dryer Units 130525 - Free Shipping on Orders Over... (https://www.summitracing.com/parts/DVR-130525)
On the Amazon site, if you click on different HP ratings the Db level changes on the description.
58 for the 3/4 hp model. My 91 (which has no HWH system) came with a 120VAC 3/4 hp Gast compressor as OEM.