MaxAir 90 O-rings Missing

[Gixxer]

I picked up a used MaxAir 90 and I thought I would change the oil and replace the filters before using it. When I removed the plug from the top of the main filter assembly to change the cartridge, I saw where it appeared two o-rings belonged. Upon checking the manual that came with the compressor I found that to be the case. My first thought was to drive up to Harbor Freight and just pick up an o-ring kit. However, I’m not sure if that’s the right thing to do…

Can someone tell me what material the o-rings should be made of and where I can order them online? The manual doesn’t list part numbers; it just references them as #7 at $3.00 and #9 at $2.00. I believe the compressor was built in the mid 90’s.

[frogman62]

If you are pumping air - only go to any location and buy the o rings probably cost you $1.00 for both. Frogman

[rcontrera]

They originally came with Viton since the MCH16 was designed to pump Nitrox, but the generics will work just fine. Just make sure that they are properly lubricated and inspect them each time you open the top. You may just have to change more often than Viton but...

As for different prices ... it doesn't make much sense since both the two top and the bottom O-rings are the same.

[Gixxer]

Thanks for the advise... I have Viton o-ring on the way. Also, I spoke with a MaxAir rep today and I got what I think is some pretty good advise. I jotted down some notes while he was talking. ...hope I didn't miss anything. Here is a copy of my notes:

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The MaxAir 90 Compressor holds 1.9 Liters of Oil

Small amount of oil (droplets) in bottom of filter cartridge chamber is normal. If more than just a few drops of oil are found at the bottom of the chamber then bad rings.

How to tell if the compressor ran hot:
1. Burned oil is found at the bottom of the filter chamber (or elsewhere).
2. If you rub the oil between your thumb and finger and you feel grit.

When replacing filters do not leave assemblies open for very long. Even small amounts of debris can greatly shorten compressor life.

Change main filter cartridge every 50 hours. Be sure to bleed air from bottom of assembly before removing plug. If you don’t, plug threads could be damaged. Plug should be put on snugly but not too tight. You should almost be able to remove the plug by hand by using thumb and a finger on two Allen head bolts. Be sure to use silicon grease on o-rings and threads. Silicon grease only and do not use silicon grease that comes in a spray can

Intake filter … When rotating or replacing, clean inside housing with a damp cloth, check for corrosion

Other filter / screen: Near the oil drain at back right you’ll find two solenoids, a black one and a silver one. The silver one has a filter that that needs to be periodically cleaned or replaced.

Clean valves at 1000 hours
Replace valves at 2000 Hours
Re-ring machine at 3000 hours (If cylinder walls still show crosshatching the re-ringing may not be necessary

To check compressor:
1. Hook up aluminum 80 tank and pump 500 pounds into it.
2. Close aluminum 80 tank valve.
3. With aluminum 80 tank valve closed, pump up compressor until pressure reaches 3000 PSI (fills internal compressor lines, components, etc.)
4. Open valve on aluminum 80 tank. If compressor is good it should take about 7.5 minutes to fill the tank.
To check if compressor needs to be re-ringed:
1. With compressor off and all pressure bled (bleed valve below filter cartridge)
2. Remove filter cartridge
3. Use lint free cloth on a rod to swab /clean out bottom of filter assemble
4. Replace filter
5. Carefully clean plug and threads
6. Clean O-rings
7. Apply silicone grease to the threads and o-rings. Use silicon grease only! Do not use silicon grease that comes in spray can.
8. Replace plug
9. Run compressor for 5 minutes
10. Purge pressure
11. Remove filter cartridge and inspect bottom of filter assembly
If assembly has oil collected in it then the rings are bad. Note – a few droplets of oil will be normal to see when the filter is changed after 50 hours.

[rcontrera]

Change main filter cartridge every 50 hours.

Hmmm ... this doesn't seem quite right unless you have some after market filters. The standard filter that comes with the MCH13 and 16 is a 9000 cubic foot tower. That works out to about 16 hours under perfect conditions.

[oxyhacker]

My old Nautica badged MCH6 had a sticker on the stack that said "Change Filter Cartridge Every 50 hours". It also came with an orange cartridge contiaining nothing but carbon.

I recall hearing from a compressor shop claim that Nautica had dropped Coltri after a lawsuit concerning lypoid pneumonia allegedly caused by breathing dirty air, which could very well have happened using the old cartridge for that long. The new LF cartridges, which contain 13X sieve, are a major improvement, as long as they are scrupulously changed when necessary.

Oh, re O-ring composition, it shouldn't make any difference if the rig is being used for pumping nitrox or not, since it will still be 40% or less when it hits the stack.

Hmmm ... this doesn't seem quite right unless you have some after market filters. The standard filter that comes with the MCH13 and 16 is a 9000 cubic foot tower. That works out to about 16 hours under perfect conditions.

[rcontrera]

My old Nautica badged MCH6 had a sticker on the stack that said "Change Filter Cartridge Every 50 hours". It also came with an orange cartridge contiaining nothing but carbon.

I think that it also had a note in the manual (at least in the Coltri manual) to change the oil every 250 hours. This is the biggest reason that these little guys left a bad taste in owners mouths.

The filter cartridge that comes from Italy now is all black and filled with all 13X. When we get the compressor, we rip that out and put in a LF triplex or duplex filter cartridge and install a priority valve.

However, the MCH16/MA90 is a totally different machine.