eBay compressor

[avator]

Point taken..
My question was only concerning warranty. No argument here.

[Killfire]

The seller I bought from offers all sorts of replacement parts. I'd rather buy those than attemping to ship back a 50lb unit. Shipping was $150 alone. Everything inside it looked like parts would be fairly easy to source as well.

[Wayne52]

I agree with what Marko is saying.  Right kind of oil for the right kind of application, viscosity is important I think.  I wouldn't use regular engine oil in a pcp compressor myself.

[lennyk]

What is the max size tank that these compressors can be realistically used to fill ?

Can they do scba 66cf 88cf ?
or more for the little ones ?

[Trad]

Killfire
   Where did you get your moisture indicator and what brand did you buy ?

[Wayne52]

What is the max size tank that these compressors can be realistically used to fill ?

Can they do scba 66cf 88cf ?
or more for the little ones ?

I would think they would work on an 88cf scba if allowed to cool periodically but don't really know for sure.

[Killfire]

Killfire
   Where did you get your moisture indicator and what brand did you buy ?

https://www.augustindustries.com/shopdisplayproducts.asp?id=25&cat=Visual+Indicators

[MJP]

There is no proper water separator, you'll be bleeding it off like every 5-10min. And there's no dryingmedia so you'll need an external molecularsieve filter on the high side.
I wouldn't use it for large tanks but everyone does the best they see fit.
Will it fill a large tank, yes maybe, will it survive that in a long term use is anyones guess.
Heat is the main problem, getting that away from the oil. Run and let it cool to ambient run again.
Buy a good filter and separator. Then try and see what gives first.

Marko

[elguapo99]

This one (MSV-4L) from Mylondair claims to be 3 stage and fill up to a 6.8L bottle: http://mylondair.com/product/html/?106.html
It really doesn't look any different than the other small Chinese compressors that they and others are selling so I'm not sure that the specs are valid. I was quoted a price of $250 + $115 shipping to my door.

[Killfire]

There is no proper water separator, you'll be bleeding it off like every 5-10min. And there's no dryingmedia so you'll need an external molecularsieve filter on the high side.
I wouldn't use it for large tanks but everyone does the best they see fit.
Will it fill a large tank, yes maybe, will it survive that in a long term use is anyones guess.
Heat is the main problem, getting that away from the oil. Run and let it cool to ambient run again.
Buy a good filter and separator. Then try and see what gives first.

Marko

Mine doesn't have a separator or drier. I don't mind purging water every few minutes and I'm going to make something to hold the sieve before the indicator.

[MJP]

Remember to do it properly, you are designing hpa filter for pulsed duty cycle, 0-4500psi so safety factor needs to be high enough. 3.5:1 atleast. Make it too weak and you have a pipebomb on your hands.

That mylondair is not 3 stage for sure, where do you put the third stage?

Marko

[Killfire]

Remember to do it properly, you are designing hpa filter for pulsed duty cycle, 0-4500psi so safety factor needs to be high enough. 3.5:1 atleast. Make it too weak and you have a pipebomb on your hands.

That mylondair is not 3 stage for sure, where do you put the third stage?

Marko

Mine came with a "filter". Pretty much a tampon in an aluminum tube. I've taken it up to 4k PSI and it holds well. I have to measure the wall thickness but I'm going to guess it's near 1/4". My thought was to get a tight fitting piece of PVC and pack that with sieve. The aluminum will reinforce the PVC while also making it removable so I can put the media in and pack it. I'm going to take it into work tonight to measure and see what materials I can find that might be better than the PVC idea.

[elguapo99]

The only difference that I can see between the Mylondair and others is that the Mylondair MSV-4L is running at 3800 RPM if their specs are correct. I certainly don't see 3 stages. Maybe I'll have to buy one to find out for sure.

My Chinese hand pump came with a similar filter and the tampon has yet to see any oil or water contamination. So, either their isn't any contamination or the tampon is not filtering it. It seems to be a very dense/absorbent material so I would expect it to trap something.

[Jman2311]

The only difference that I can see between the Mylondair and others is that the Mylondair MSV-4L is running at 3800 RPM if their specs are correct. I certainly don't see 3 stages. Maybe I'll have to buy one to find out for sure.

My Chinese hand pump came with a similar filter and the tampon has yet to see any oil or water contamination. So, either their isn't any contamination or the tampon is not filtering it. It seems to be a very dense/absorbent material so I would expect it to trap something.

Having one of these chinese pumps I can tell you that some of the specs on Mylondair seem to me to be doubtful.  First off,  There is no doubt in my mind that given enough time and running cycle, a 6.8l tank could be filled.  However this would take a long time and multiple sessions if you wanted your pump and tank to be treated with the kind of respect HPA requires.  Unless they redefine what a stage is, there are only 2 compression stages.  There is a typical piston found on basically every reciprocating air compressor ever with a second piston that looks to be brass riding atop the 1st stage piston.  That second stage has the water cooling jacket.  The device in the middle of the 1st stage and the second stage is  an area for oil/water to accumulate in an attempt to keep it from getting to the 2nd stage.  The device on the right side of the unit is the same thing for post 2nd stage.  Thus the bleeders at the bottom.  My compressor like the msv-q4 has the same thing going on in the larger head atop the 1st stage thus why I bleed both during operation at a frequency of about 1.5-2 minutes.  Trust me, quite a bit of moisture is condensed out of the air during the process so it is important to do it often as to keep the "reservoir" from filling up.  Last the RPM of the motor is very likely not 3800rpm.  The maximum speed of an electric motor, also known as syncronous speed, is governed by the function MaxRPM=(120*Frequency in hertz)/Number of poles.  Since you must have an even number of poles, IE north and south magnetic polarity, you'll find that a motor running at the 50hz they are supplied is only capable of maximum speeds of 3000rpm.  But you'll never see those speeds or else the motor would produce no torque and it is the torque that does the compressing.  That is why some of the other models show 2800rpm, that is a more realistic speed once the slip of the motor is taken into account.  No slip, No torque.  Physics is what it is.  It is the same reason you'll see your bench grinder probably showing 3200rpm ish.  60hz on a 2 pole motor gives 3600rpm max, factoring in slip you'll get the rated rpm.

All in all, these compressors are good for what they are but the claims on the MSV-4L aren't adding up to me.  If anyone chooses to get one of these compressors, understand that they must be babied as they just are not designed as well the big names like bauer, coltri, carrette, and omega but they can get the job done.

[elguapo99]

Jeremy,
Great explanation. The specs didn't add up for me either.

[lennyk]

So what size tanks are these compressors meant for filling on a regular basis ?

[avator]

I see specs from 1.5L to 3L ?

[Taso1000]

Hi All,

I have a question about the water accumulation and the bleeding every 5 - 10 minutes.  What happens if for some reason you get distracted and don't bleed the water?

Will the water accumulate and cause the compressor to hydro lock and damage the piston, rods etc. like an internal combustion engine?

Thanks,

Taso

[avator]

Or worse yet.... get into your gun.

[Jman2311]

2L is the highest I would go personally but everyone is different.

The compressor won't hydro lock because of it's design. The valves won't allow that.  You don't want that in your gun though. I won't go into details here as they are well known and available in many other places.  You should not operate this pump unsupervised without timers timings.  It is better to shut off under pressure if an emergency happens rather than to let it keep on chugging along for indefinite amounts of time with no supervision.