My initial thoughts on my new compressor

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jlcnuke

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So, as some who look in this forum know, I've been researching and learning about doing my own fills and settled on buying a compressor and making my own nitrox stick. Today, my brand new compressor arrived, and I promptly got to setting it up and getting it into service (without the nitrox stick at this point as I needed the compressor to determine the final fittings to connect the nitrox stick). Here's my current thoughts on it:

Compressor:
Coltri MCH-6, with stainless steel frame, 220v single-phase electric motor, auto-shutoff factory set for 3,750 psi.

Buying and getting the compressor:
Buying the compressor consisted of calling Nuvair (based in California), specifying what I was looking for/wanted, and getting that all sorted out. I elected to buy spares for the filters and oil at the same time as they were giving a 20% discount on those parts with compressor purchase so I got 7 extra breathing air filters, 5 inlet filters, and an extra gallon of oil on top of what comes with the compressor to start with. A PRV came standard as part of this model in the US, so I didn't have to pay extra for that, though from what I've read that may not be the case in Europe/elsewhere. I ordered the compressor the week before July 4th, and was told to expect it to be built the following week, tested and ship the week after that (12th-16th). It actually shipped the Tuesday the 27th, despite my salesperson telling me on the 14th that it was in line for testing and should ship "in the next day or two", then telling me on the 23rd that "it is shipping out today". There were a couple emails and one call I made in those last two weeks before it actually shipped that went without a timely response or any specific information given (including going to voicemail with no call back or email response for days). Needless to say, I wasn't thrilled with the customer service or timeliness of the shipping by the time it finally did ship.

It arrived today, with minor damage to the outside of the shipping box, but no damage to the interior parts. a random bolt and washer was loose inside, but does not appear to be missing from any of the connections on the unit itself. I wired up the plug after looking up the EU wiring colors as the wire came with brown, blue, green/yellow wires instead of US colors (the wires are 14 gauge for anyone interested, and are fine with a standard 3-prong 220v plug). The manual states that it ships without oil or a filter in it, but mine arrived with oil and the filter both already taken care of. That's nice as the qt of oil that comes with it was also still full, giving me an extra oil change worth of oil, and it shortened my time to get it in service today.

I bought an extended whip, with the upgraded whip adapter for filling DIN tanks with a pressure gauge on the whip end. In retrospect, I wouldn't get that end again as the pressure gauge is tiny and barely readable, certainly inadequate for any sort of gas blending. I'll be replacing that with a new pressure gauge I ordered today.

Operation is quite simple. The noise level is stated as 82db iirc, and it's pretty accurate. Standing 3 ft from the compressor it's possible to have a conversation without raising your voice. With the compressor inside the garage, and my work computer about 10' inside the house on the other side of the door to the garage I can barely tell the compressor is running (about the same noise level as the A/C running), so if a friend is pumping up a tank in the garage I could still be holding a Teams/Zoom meeting without anyone knowing there's a compressor going at the time. Blowing down the vents manually isn't much of a chore, but I was surprised to note that there is visible oil probably every 2-3 blowdowns (doing ~10 minute intervals) in the discharge from the moisture separator. I'll be keeping an eye on that and the oil level moving forward. Fill times are running about 8 minutes per 1,000psi in an AL80 tank. Going from 2,600 to 3,600 psi in LP95 doubles took 19 minutes. The auto-shutdown I purchased was set right at the 3,750psi I asked for, and with the slow fill rate gave me a final cooled off fill pressure on the doubles of right at 3,600 psi.

Overall, so far I'm pleased with the compressor, it's operation, and ease of setup, though I was disappointed with the communication and time it took to get it shipped in the first place. Not sure if seeing visible oil in the separator is normal or something I need to be concerned about, but I'll be keeping an eye on it and the breathing air filter. I'll also be placing oil absorbent pads under the moisture separator drain in the future. I plan on checking the visual indicator on the filter every hour of use for the first 15-20 hours and I'll replace that at the first sign of color change on the blue indicator, then track it's performance on the next filter to get a baseline.

I'm also looking at running the suction into the basement of the house to get cooler, dryer air for the compressor suction, which should extend filter life some I believe from my research.

I'll hook up the nitrox stick and route all that stuff later this week and try it out when doing fills next week probably. For use, I'll be doing a 30 minute rest period after any doubles filling as well, as my research suggests that the duty cycle is fine with doing AL80's but is best to not use continuously with larger volume/higher pressure fills.

Coltri MCH-6.jpg
 

michael-fisch

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What should I say, you bought an MCH6 instead of spending the bucks on a Bauer. I hope that you have good luck and never regret your decision, but that's a decision that I would have never made.

Michael
 
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jlcnuke

jlcnuke

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Well, there's a bit of buyer's remorse today. I ran the compressor for ~5 hours, did the initial oil change etc. at that point. The compressor came with oil and a filter installed (manual says it doesn't, but mine showed up with them installed), but being weary of the filter's life I've been checking it about every hour to see if the blue strip had changed colors. I filled a bunch of tanks, did the 5 hour maintenance, then filled a couple more tanks. Today I went and dove 2 of the tanks I'd filled fairly early on. One was fine, the other one had a distinct oil taste/smell to the air. Sure enough, just about everything after the first three or so tanks filled was contaminated with oil/hydrocarbons. I've disassembled, cleaned, and put back everything from the filter through the whip as best I could and wasted a filter already (first replacement quickly had the same oil/hydrocarbon on the outlet when I changed just that to start with) and have just finally got the smell and taste of oil/hydrocarbons gone from it (for now?).

I've been blowing it down religiously at ~10 minutes (sometimes less) every fill, so I can only guess that something about shipping it full of oil with the filter installed messed up the filter media and had it letting oil/hydrocarbon carryover even after just an hour or so of use. I'm now having to go drain, clean, and re-VIP every tank filled since then as well over the next few days, then fill them (and check for any bad fills for each tank at this point). I'm less than pleased today to say the least. I've sent an email to my sales agent from Nuvair to let them know of the situation and my displeasure, we'll see what comes of that. While I'm hopeful it was a problem with just the Coltri filter it came with, I'll be testing every tank after it's filled for the near future for any issues. I'll also be ordering LF filters asap. Re-O2 cleaning all the tanks is also a trouble I was not wanting to have to deal with this week as a result of this contamination.
 

NothingClever

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What a bummer. Sorry to hear your bad news, mate. I hope you’re able to get it sorted without excessive downtime or any personal expense.
 

happy-diver

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Take it back and put it in someones bed, before you messed with it

Buyer's remorse - Wikipedia

Once upon a time we had a couple of the local shop noodles transport a Verticus
on it's side in an open trailer and expected to put it immediately into nitrox service

When one guy refused to sign off on it they found another guy that would but no nitrox

Yes dive shops stay away from dive shops
 

2airishuman

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Thank you for the report and updates. Please post up as you learn more.
 
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jlcnuke

jlcnuke

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Reply from Nuvair today:
"We were notified last week that there was a machining issue with the filter tower where the o-ring might not seat properly. This would explain why it passed air analysis but you are still experiencing a taste. This new cap pushes the filter down further so the o-ring is fully engaged. I am sending out the new cap with gauge and a couple filters. Let me know if you have any questions."

I'll hold off using the compressor until the new cap gets here and then I'll see how it performs with the new cap and filters installed.
 

happy-diver

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It's exciting having a new compressor, I have 3 Bauers and am awaiting another in pre-delivery

All in the pursuit of happiness

I will sell two with the purchase of my latest, it's encased and quiet


Your issues have only just started Jeff, put your excitement aside an engage your brain, send it back to the bums

There were a couple emails and one call I made in those last two weeks before it actually shipped that went without a timely response or any specific information given (including going to voicemail with no call back or email response for days). Needless to say, I wasn't thrilled with the customer service or timeliness of the shipping by the time it finally did ship.

This will only get worse, the pain immense


It's only a bit more time and a bit more saving for another, my Bauers are one new, three used second hand
 
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jlcnuke

jlcnuke

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It's exciting having a new compressor, I have 3 Bauers and am awaiting another in pre-delivery

All in the pursuit of happiness

I will sell two with the purchase of my latest, it's encased and quiet


Your issues have only just started Jeff, put your excitement aside an engage your brain, send it back to the bums



This will only get worse, the pain immense


It's only a bit more time and a bit more saving for another, my Bauers are one new, three used second hand

The only current "problem" I repeatedly see regarding these compressors continually come up with any reliability is "the filter is small so you have to replace it often". For those of us filling only a couple hours per week, that's a really minor inconvenience at the price of saving thousands of dollars compared to going with a Bauer JR II etc. (and no, I don't want a 20 year old, who knows the condition of any of the components used one to deal with either). As such, this issue notwithstanding, I've found absolutely no reason to not stick with the compressor if this was truly a manufacturing defect that will shortly be corrected. If you are aware of things that make this compressor unlikely to perform properly in the future and can cite what those issues are, I'd be happy to hear them so I can be informed and prepared. I've already reduced the maintenance intervals for me personally just for peace of mind (doing oil changes every 25 hours, not waiting til 500 hours for a valve service etc.), but even with those conservative adjustments for the compressor (and increased costs as a result) it seems to me that I'm going to come out ahead monetarily AND have a compressor that will adequately perform everything I need from it compared to spending thousands more for a BJII...
 

iain/hsm

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Reply from Nuvair today:
"We were notified last week that there was a machining issue with the filter tower where the o-ring might not seat properly.

But we could'nt be bothered to tell you until you found out so now we are sending you a cheap $19 part to shut you up and keep you happy.

This would explain why it passed air analysis but you are still experiencing a taste.

Really..... are you going to believe that lie?

Let me know if you have any questions.

Yes I have one. Where do I send it back to and when do I get my money back?
 

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