Outboard Air Compressor

[Emcemv]

Chuck

Nice write up on the compressor. I just tried my small pancake compressor this last weekend and it was noisy. Your system could easily be built in.  Another project for me!!

[Chuck Hancock]

Bruce,  if you decide to try it let me know.  I have one that I "experimented" with that you can look at to see what you are getting into.  The write up makes it sound like more of a job than it really is (Peter helped me add condensors to kick start them when running on the inverter). 

[rv_safetyman]

A few years ago, there was a thread that talked about making sure you bought an compressor with an oil sump rather than oil less.  Supposed to be quieter.  I bought a sears unit that someone recommended and it was terrible.  I think it was this one:

http://www.sears.com/craftsman-3-gallon-horizontal-air-compressor-with-hose/p-00915310000P

Assuming that is the same one I bought (fairly sure) it is rated at 2.4 CFM at 90 PSI.  My guess is that it delivered far less.  Also after little usage I had to rebuild the top end.  It was not all that quiet.  Gave it away on Craigslist.

I contacted Sean to see what he used and his was an  Hitachi -EC119SA.  Here is one source:

http://www.amazon.com/Hitachi-EC119SA-2-5-Horsepower-Twin-Stack-Compressor/dp/B000G6C7XQ

That compressor is rated at 4 CFM at 100 PSI.  

I bought a reconditioned unit and am moderately pleased with it.  As was the case with the Sears,  I am not convinced that I am getting 4 CFM.  If you try to run a good 1/2 inch impact off of it, you will get very frustrated quickly.  Then again, I am spoiled by a "REAL" compressor (5 HP Quincey).  The foot print of the Hatachi is quite a bit bigger than the Sears and I had to do some arranging to get it situated in the bay.  The only issue I have with it, is that the motor overload will kick out when the compressor is cold (maybe 30*).

It is louder than I would like, but with the bay door shut, it is acceptable.

In this, and similar threads, folks talk about enclosing the air compressor in a sound box.  If you do, be sure to have some sort of air circulation system.  Those suckers will get pretty warm in an enclosed box.

Jim

[Emcemv]

This has been a great discussion, really shows the value of this forum!  I connected up my small compressor to the bus last weekend and tried to air it up from zero. It took forever and ran the little compressor to death.  Then I got thinking about unfiltered wet air going in to the bus system and stopped. Our bus holds air about a day and I was looking for something to use while camping just to keep the air up so I think this may work in that situation.  Once the weather improves, I will be under the bus to see if I can find any leaks and that may also improve my situation. I'm going to get a filter and dryer for it and feed into the bus air through a check valve as well. My small compressor is a 6 gallon, 2.5gpm 150 psi unit.

Chuck - does your system feed the whole bus air system or just the 7 gallon tank for the toilet?

[Chuck Hancock]

Bruce,  I have it setup so that all of the compressors (bus compressor, Aux air installed by Liberty and the two refrigerator compressors I installed ) feed the small tank I installed to operate the toilet.  However when the bus is parked and I don't want to run the motor or the Aux air (very noisy) then I use only  the refrigerator compressors and they feed just the small  toilet air tank.  They are blocked from sending air back to the aux tank or main tanks by the use of a check valve.  By changing a check valve I can allow air to  go  to from the refrigerator compressors to the Aux tank and the main bus tanks but have not had a need to do that. 

When the bus has had the air dumped from the leveling bags or the brake air  is  low from sitting for an extended period of time and I want to get underway I  use the Aux air or run the motor as they are much bigger compressors and build the air up much faster.

[Chuck Hancock]

Bruce, I see comments  on here about  using compressors that add moisture or oil to the air.  I specifically modified the two refrigerator compressors  to make sure that they did not add moisture or oil and also installed a "dryer / water / oil" separator in the line to insure dry, clean air.   There is no advantage I know of to adding moisture or oil to any air system (other than air conditioning) .  Moisture is naturally added because  of the heat from the compressors and oil can get in if you use a compressor with an oil sump (like the modified refrigeration compressors I used) so you need to design the system to take clean the air up and take out any moisture or  oil.

[Lin]

We have a small, old Inglo dual tank compressor.  I think it is the type someone would bring to a construction job to run nail guns, etc.  I almost always use it to air up the bus so we are ready to go at the turn of the key.  When camping, I use it to top off the air once a day so the air bags won't deflate and change our level.  I have not timed it to see how long it takes to go from 0-120. I'm sure it's between 5-10 minutes.  Since there is always something else to do, I never notice.  If I was in a rush to get started, I would just use the engine compressor at 1000+rpm.  I really do not think that we use it enough to put any significant amounts of pollutants into the system, and whatever there is gets purged either automatically or when I pulled the valve cable after a run.

It is a great convenience and a nice back up for tires and tools.  Now, my compressor is rather noisey, but not near as much as the airless one we used to have.  Ed H. once showed me his compressor.  It's bigger than mine but much more quiet.

[Scott & Heather]

So all this talk about keeping your bags inflated...bunch of windbags we are...anyway, we hate sitting on our bags. When we are parked for just a night or two, I don't stick our jacks under there..and she bounces. Someone gets up in the middle of the night to go to the restroom...coach bounces. Someone gets up early to have some breakfast...coach bounces. Ugh. When she's on jacks...she's solid as a real house. Love it! I never rest the coach on its bags...only on jacks all the way around. Level it, and it just is so solid. Even strong strong gusts of wind don't rock it at all...

[Chuck Hancock]

Lin, you are right.  I am sure the way you described using the compressor will not cause any problems.  My coach requires air to flush the toilet and keep it level and when I am parked for extended periods (I park for as much as three months when I go to calif for the winter) and I designed my system to minimize any contaminants.  

Scott, I would love to have jacks but just have 8 air bags. 

[zubzub]

A few years ago, there was a thread that talked about making sure you bought an compressor with an oil sump rather than oil less.  Supposed to be quieter.  I bought a sears unit that someone recommended and it was terrible.  I think it was this one:

http://www.sears.com/craftsman-3-gallon-horizontal-air-compressor-with-hose/p-00915310000P

Assuming that is the same one I bought (fairly sure) it is rated at 2.4 CFM at 90 PSI.  My guess is that it delivered far less.  Also after little usage I had to rebuild the top end.  It was not all that quiet.  



Jim

I think you got a lemon...or I got the opposite of a lemon.  Bought the same compressor on recommendation of the board ( 6 years ago) and still have it...use it for work sometimes and always for the bus because it kicks in easier than my big Comp and doesn't drag my generator down.  It is pretty quiet (there are quieter ones) but I like the light weight, small footprint and durability.

[rv_safetyman]

Now that you mention it, I recall that the Sears unit was well recommended.  It sure had a nice footprint and was OK on noise. 

Yes, I probably got a lemon - story of my life

Jim