Question Scuba air compressors dos and don'ts

[phgachoud]

Hey all!
just acquired a year ~2000 coltri MCH-6 am wondering if you guys can help me building up for all people (and our children ) a list of does and dont with your own compressor! Maybe there are some stuff which are brand/model specific and others which are general. Beyond the famous RTFM, what do you guys advise?

Anything going through your head might be logical for some but not for others, so anything welcome!

Thx!!!

 

[happy-diver]

If you're going to fluff fluff down wind

 

[runsongas]

expect to change the oil and filters more often than stated as the smaller coltris tend to run hot. get inline detectors to save your butt.

 

[Darnold9999]

It has been a very long time since I owned a compressor but don't scrimp on filters or oil. The quality of the air going in is critical. i.e. don't run it anywhere near a source of CO or CO2 or any other contaminant. This is particularly an issue with a non electric compressor that is itself a source of contaminants.

 

[phgachoud]

expect to change the oil and filters more often than stated as the smaller coltris tend to run hot. get inline detectors to save your butt.

What do you mean by inline detectors? can you be more specific and show a picture of what you mean by that? Thx @runsongas !

 

[PR_SMITH]

What do you mean by inline detectors? can you be more specific and show a picture of what you mean by that? Thx @runsongas !

Visual Indicator Housing with CO & Moisture Elements

Visual indicator housing with 1/4 in FNPT inlet and outlet. Supplied with carbon monoxide (CO) and moisture (H2O) elements. Rated to 6000 psi (414 bar).

nuvair.com

 

[rob.mwpropane]

What do you mean by inline detectors? can you be more specific and show a picture of what you mean by that? Thx @runsongas !

Inline detectors detect moisture content if that's the disk you have installed (although I think it's better to just track your filter life than rely on those).

Your best bet is to familiarize yourself with this document and all the abbreviations and why things are in line where they are (it does not have an in line detector or "site glass"). Then apply it to your compressor and see what it has and what it doesn't have. Maybe it needs some things, maybe it doesn't, but you should have a good understanding what all the parts do.

Compressor Filter System Theory - Scuba Engineer

High Pressure Breathing Air Compressor Filtration System Design author:- Stephen E Burton BSc(hons) C.Eng, MIET - Email to:- scubaengineer@gmail.com

scubaengineer.com

No offense, but it's obvious you haven't done a ton of research. Not at all knocking you for it, we all have to start somewhere, but your best bet is learn as MUCH as you can on how the compressor works and then start asking questions.

 

[PR_SMITH]

Inline detectors detect moisture content if that's the disk you have installed (although I think it's better to just track your filter life than rely on those).

Your best bet is to familiarize yourself with this document and all the abbreviations and why things are in line where they are (it does not have an in line detector or "site glass"). Then apply it to your compressor and see what it has and what it doesn't have. Maybe it needs some things, maybe it doesn't, but you should have a good understanding what all the parts do.

Compressor Filter System Theory - Scuba Engineer

High Pressure Breathing Air Compressor Filtration System Design author:- Stephen E Burton BSc(hons) C.Eng, MIET - Email to:- scubaengineer@gmail.com

scubaengineer.com

No offense, but it's obvious you haven't done a ton of research. Not at all knocking you for it, we all have to start somewhere, but your best bet is learn as MUCH as you can on how the compressor works and then start asking questions.

There's some good info on that site; but there is also one alleged flaw in the diagram shown.
I have had discussions with several compressor techs and they advise that the NRV is better placed between the towers, and not immediately after the compressor. The rational is that the NRV causes the compressor third stage, on startup, to have to instantly work against the pressure in the first tower. Ideally, the first tower should be drained after every session, to remove all moist air, water, and relieve all pressure. The second tower should always be kept at or above the PMV setting, for max filter life.

Thoughts?

 

[rob.mwpropane]

There's some good info on that site; but there is also one alleged flaw in the diagram shown.
I have had discussions with several compressor techs and they advise that the NRV is better placed between the towers, and not immediately after the compressor. The rational is that the NRV causes the compressor third stage, on startup, to have to instantly work against the pressure in the first tower. Ideally, the first tower should be drained after every session, to remove all moist air, water, and relieve all pressure. The second tower should always be kept at or above the PMV setting, for max filter life.


Thoughts?

I have only ever worked with my Rix, so take anything I say with a heaping table spoon of salt, lol.

I wouldn't take that link as the bible of compressors, just a good starting point.

NRV (No return valve) is just check valve. The diagram shows 2 coalescres and then a separator afterwards and then the filter tower. My system does not have a separator afterwards like that. I have 2 colaescers and then just the filter tower. I can't imagine a compressor starting with either coalescer pressurized, mine are always bled to zero after each time I use the compressor. I do leave the tower at 22-2400 psi or so. So I think I agree with your techs reasoning, but in the diagram (to me) it wouldn't matter because each of the stages still have to fill up and also each coalescer before pressure gets to the NRV. If I owned this exact system and a guru tech told me to drain the final separator I would though, no problem. It might take all of 10 seconds to fill it back up. Draining the filter (to me) is really the only major no no to save filter life.

If you were to remove the last separator and the SV in the diagram that's pretty much my system more or less. I actually want pressure to build rather quickly in my system to seat the 3rd stage floating piston, so mine has a PMV directly after the 2nd coalescer and then another after the filter tower (but that's because I disconnect the tower and compressor separately for transport around the shop).

Compressor "theory" should just be a good starting point for anyone getting one. I would say read this and then learn as much as you can about whatever system falls in your lap.

 

[rhwestfall]

This is plumbed in at my whip as a tee and feeds my detector....​

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