Best Practices

[Keith73]

I'll keep it brief.

My Situation: offer support and guidance to other techs.

My Question: Your oppinion on the actuall use of nitrogen and micron gauges in the field. What percentage of techs actually do as they are instructed.

It can be obvious at times during follow-ups what was not done or done wrong.

[Bob-TechTrainer]

I'll keep it brief.

My Situation: offer support and guidance to other techs.

My Question: Your oppinion on the actuall use of nitrogen and micron gauges in the field. What percentage of techs actually do as they are instructed.

It can be obvious at times during follow-ups what was not done or done wrong.

I am the technical training manager in a large atlanta based company. We regularly inspect our 30 plus techs tools and practices. we use micron guages on every system we open and purge with nitrogen. Some may try to cut corners but we pay them well enough and we check up on them and the customers fill out our survey cards.

[coolerinfrederick]

opinion no, it is second nature

[shaun66]

been doing markets for 20+ years, have never seen a N2 purge on any install

[jpsmith1cm]

been doing markets for 20+ years, have never seen a N2 purge on any install

I haven't been doing it that long, but I've not seen n2 on an install, either.

Micron gauges, yes, but nitrogen no.

Not dismissing the importance of it, its use would make life a lot easier for the start-up guy, just stating facts.

[shaun66]

I haven't been doing it that long, but I've not seen n2 on an install, either.

Micron gauges, yes, but nitrogen no.

Not dismissing the importance of it, its use would make life a lot easier for the start-up guy, just stating facts.

I am the startup guy, rarely get a tx screen plugged, maybe 1 screen in every 10 rack startups.

[jpsmith1cm]

I am the startup guy, rarely get a tx screen plugged, maybe 1 screen in every 10 rack startups.

WOW!

Your fitters must be good.


Start 'em, let 'em run a day, come back and clean screens and set TXVs.

That's how we do it.

Well, that or throw the valves and cross our fingers that everything works which is how some others prefer to operate.

[icemeister]

(This thread should be moved to Refrigeration & Icemaking...or at least Commercial.)

It rather surprises me that you two very experienced market techs have never seen nitrogen purge on installations.

Way back in the mid 1980s, when I was in charge of installations for a chain in New England, we had as part of our written installation specifications that a nitrogen purge shall be used at all times during brazing.

Further, the specs stated that we had the right to cut out, at random, any fitting in the system to inspect it for oxidation and scaling. If the inspection failed, we could call for the entire system to be redone.

A full repipe never happened to my knowledge, but there were cutouts done.

I'll have to dig out a copy of those old specs and post them.

As a matter of fact, I had a new contractor on a job who when I showed up unannounced for a site check, they reviewed their N2 setup and policy with me. I couldn't help but noticed the 10-12 large nitro cylinders stocked in the back room.

They actually had two test fittings ready for me, showing the difference between brazing with nitrogen and without.

I never bothered them after that about purging...and the startup socks in the suction filters were as clean as I've ever seen.

[jpsmith1cm]

(This thread should be moved to Refrigeration & Icemaking...or at least Commercial.)

It rather surprises me that you two very experienced market techs have never seen nitrogen purge on installations.

Way back in the mid 1980s, when I was in charge of installations for a chain in New England, we had as part of our written installation specifications that a nitrogen purge shall be used at all times during brazing.

Further, the specs stated that we had the right to cut out, at random, any fitting in the system to inspect it for oxidation and scaling. If the inspection failed, we could call for the entire system to be redone.

A full repipe never happened to my knowledge, but there were cutouts done.

I'll have to dig out a copy of those old specs and post them.

As a matter of fact, I had a new contractor on a job who when I showed up unannounced for a site check, they reviewed their N2 setup and policy with me. I couldn't help but noticed the 10-12 large nitro cylinders stocked in the back room.

They actually had two test fittings ready for me, showing the difference between brazing with nitrogen and without.

I never bothered them after that about purging...and the startup socks in the suction filters were as clean as I've ever seen.

Ice,

It's STILL in the job specifications that I've read, exactly as you describe it. Nitrogen purge MUST be used and the customer has the rights as you described.

I just think that some customers are much more lax about enforcement than others.

I can remember hearing some of the fitters b***h about jobs where the HAD to do the purge in cases where the customer was not lax about enforcement.

About all that is done is to verify the presence of nitrogen on the jobsite. Doesn't matter if it's used or not, just has to be there.



Part of the problem may have something to do with the evolution of the rack system as I'm seeing it.

We aren't seeing the 'standard' system anymore. By 'standard' I mean one liquid line and one suction line from the rack to the case. In this case, particularly during a remodel, it is easy to set up a purge and to do it.

Newer systems are 'looped' systems with a large liquid line or two or three running through the store with similarly large suction lines paralleling them and EEPR valves controlling the individual circuits.

Much harder to use a nitrogen purge in this type of arrangement as there are fewer access points and those that exist are harder to access to use as a point for introducing nitrogen to the system.


Then again, maybe contractors have gotten cheaper and fitters have gotten lazier.


I'm not sure which is the case.

[Keith73]

I apreciate everyone's feedback! I hope to get more.

[pecmsg]

The old refrigerants and oils were very forgiving. As JP said run the systems for a day and pull and clean the screens was SOP.

POE oil changed all that. POE is a solvent as it circulates through the system. Scale that would probably stay put before is now flushed down stream.

JP I would suggest changing suction filters and cleaning the strainers on the pumps as well. You’ll be surprised at the amount of crap in them.

[jpsmith1cm]

The old refrigerants and oils were very forgiving. As JP said run the systems for a day and pull and clean the screens was SOP.

POE oil changed all that. POE is a solvent as it circulates through the system. Scale that would probably stay put before is now flushed down stream.

JP I would suggest changing suction filters and cleaning the strainers on the pumps as well. You’ll be surprised at the amount of crap in them.

Yep.

Big pressure drops across driers and filters.

The refrigerant and oil technology has moved on and, sadly, some have chosen to not keep up with the technology.

What I described is still being practiced on R-404a rack systems.

[beachtech]

have never purged with N2 during install or service repairs.

always use micron gauge to ensure a proper vacuum is pulled. If your techs are cutting this corner, it may be in part to lack of training to proper procedures and methods to pull a fast good vacuum. Utilizing 3/8's hoses, removing schrader cores, and a vacuum "tree" versus a manifold will cut vacuum times in half!

[Keith73]

I agree with the vacuum of course but without using N2, it is still cutting corners.

Nitrogen keeps the system clean and also purges contaminates.

Did I mention it prevents carbon deposits from brazzing?

[XcelTech]

I haven't found a company yet that would except the expense of using N2 while brazing.

I agree whole heartedly with N2 while you braze, before you vacuum, and requiring techs to use a micron gauge. I am so fanatic about my own micron gauge I used a cigar box and foam to make it a protective case.

[zartangreen]

It's Terrible for me to say but most companies would pay for the nitrogen, instead of leaving the pump over night. And following up next day losing hours.

Unfortunatly the customers up here just think its normal to change a compressor every five years.
Spend spend especially now,, right before xmas
I don't even think the customers ask y did my compressor go.??

I don't agree with this Practice


Maybe ill start a kickback thread

[shaun66]

Yep.

Big pressure drops across driers and filters.

The refrigerant and oil technology has moved on and, sadly, some have chosen to not keep up with the technology.

What I described is still being practiced on R-404a rack systems.

driers and filters are always changed after couple days run time, covered in black. they did their job

[luckee]

If the line set is less than 100 ft we will not use N2 to purge. However, in supermarkets we always use N2 regardless of the length of pipe. Afterwords we always throw a pump with a micron gauge on it.

[bwd111]

I haven't found a company yet that would except the expense of using N2 while brazing.

I agree whole heartedly with N2 while you braze, before you vacuum, and requiring techs to use a micron gauge. I am so fanatic about my own micron gauge I used a cigar box and foam to make it a protective case.

Might as welll put that in a pelican case and lock box Ive seen it all--olololololololololololololololololol