Funny gas story 1

[krugtech]

I had a laser that ran like crap. It looked like a gas problem and I looked at the cylinders and found a CO2 bottle from 1928. It was Airgas. I told the customer to get better gasses and he called the Airgas rep. The rep came and basically told me I was full of crap. I asked him how they tested the cylinders and before he could answer I blurted out "I hope you ultrasonic test them as it doesn't introduce liquids into the cylinder like hydro-testing does". He said that every bottle used in high purity applications is ultrasonic tested and they would never use a cylinder that was ever hydrotested.

I had him at this point, I pointed to the 1928 cylinder that had dates every 10 or so years where they tested it. How could they have ultrasonic test that cyl 80 years ago when ultrasonic testing has only been around for about 20-30 years?

I'll never forget the look on that salesman's face after that. it was like he stuck his foot somewhere uncomfortable.....

Chris Krug

http://krugtech.com/

Maximum Up-time, Minimum BS

 

[krugtech]

here's some info on ultrasonic testing-

http://www.specialtygasreport.com/features/361

Chris Krug

http://krugtech.com/

Maximum Up-time, Minimum BS

 

[IRstuff]

You have a gas laser from 1928? ;-)

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[HenryRollins]

LOL! 1928! I had one from 1941 about year ago. It was a O2 bottle and the customer getting a severe cut condition, crannies, looked like it was starved for O2 on thick plate and a rat chewed edge on everything thin. Swapped bottles with one from the 80's and all was well with the machine. I can't remember which supplier it was. I tell customers be careful of bottles older than 20 years.

 

[krugtech]

my personal record is 1917 but I've heard of a few that if they still exist today, they would be 104 years old. Of course they still exist, Airgas is using them!

Just read the linked article and how.... get this- when you fill a bottle with something and pressurize it really high, it's really hard to get all of that something back out...... go figure......

Another favorite is "I have another customer with blah blah blah and it runs fine on our gas". That other customer probably has a lower power laser or one that uses low current. With Bystronics, when you start getting over 70 ma you better have good gas. A 3500 runs at 85 ma and if you fart near it, it goes unstable. The 4000 Bystronic only pumps 72 ma through the tubes and runs fairly well on crap gas (of course time between overhauls suffers greatly). The gas salesmen I've met can't understand how a lower power 3500 is more sensitive to impurities than a 4000.


Henry, if anyone knows how I feel about laser gasses it's you bud.

Chris Krug

http://krugtech.com/

Maximum Up-time, Minimum BS

 

[Barneylaser]

Being from the Tri-State area if Airgas "Sucks" then who can you recommend? I have called my local (Airgas) rep 3 times and no call backs so I need a Good supplier.

 

[krugtech]

I've had good results with Praxair Laserstar.

All those certs and documents and whatnot that come with the gas bottles stating the purity- just throw them in the garbage, they pretty much mean nothing. Those specs and purity levels required are just a guideline, they're not meant to be used as a tool for a purchasing agent to find the low bidder.

All you can do is make sure your gasses come in clean bottles, expect to pay more for good gas and most importantly is simply watch how the laser runs on the gasses you're using.

The best thing you can do is check the laser power every week or so, and definitely check the laser power whenever a new gas bottle is put into service. This is where auto switching gas regulators cause problems- They decide when the new bottle is put into service. I never understood the automatic gas change system, it automatically makes sure your primary bottle of gas and your backup are completely empty before the machine gives a low gas warning........

Chris Krug

http://krugtech.com/

Maximum Up-time, Minimum BS

 

[Foostrap]

Regarding the automatic laser gas change system, some systems have an alarm box warning when one or both bottles are running low. I'd definitely recommend to get one of those.

 

[krugtech]

Footstrap, why throw more money at something you don't need? Nothing compares to a manual system with 2 bottles of each gas. The laser already has a low gas warning system, just use that with a manual change system. Cheap, reliable, simple, no surprises.

Good story about auto gas change systems- A tech finds the turbo pulling too much current, changed it out and same thing.... why is this brand new $25,000 turbo pulling too much current? He asked the usual questions to everyone he could find "did you do anything or notice anything or CHANGE GAS BOTTLES RECENTLY?" The truth is, they didn't change anything for weeks. A few weeks ago they did change out a helium bottle...... and replaced it with N2 by mistake. They made a time bomb. Jump ahead a few weeks, the auto change system does it's thing without anyone knowing and now the turbo has to try to pump a load of thick soupy N2 instead of N2 thinned out with He. Pumping soup takes more current.

Time bombs- One of my favorites is when the gas company gives you CO2 in a siphon bottle with a helium push. When the CO2 runs out (assuming the liquid CO2 didn't kill the regulator quicker) the laser now gets extra He and no CO2. The operator looks at the gasses and whadda ya know, not only do all the gasses have plenty of pressure, the CO2 which normally reads 800 psi is doing really well, it's up over 2000.

These lasers are complicated enough as it is. Try not to make it worse. Keep it simple as possible.

When was the last time anyone here looked at the laser gas bottles coming from your gas company? Are they nice clean capped and sealed new bottles, or do they have enough hydrotest dates stamped into them that they remind you of some kind of plaque on a war memorial?

Chris Krug

http://krugtech.com/

Maximum Up-time, Minimum BS

 

[Foostrap]

Krugtech, you're right for a standalone machine. But when the machine has automation, I still recommend customers to get an automatic laser gas switching system. Then you're sure you won't run out during the week-end or overnight; one less thing the operator needs to worry about before leaving. I'm not familiar with multiple laser gas bottle systems and problems they may cause; I only work on Fanuc resonators which use premix bottles (He, N2 and CO2 premixed by gas supplier). I've had very little problems with those.

 

[krugtech]

An auto gas change system shouldn't make you feel sure the machine will run unattended. The auto change system offers no advantage in this situation. The time the machine will run, be it over the weekend or whatever will be dictated by the amount of gas available. It doesn't matter if you have 5 bottles all on at once, 5 bottles that automatically change sequentially or a huge bottle that's 5 times normal size.

Out of those options, the only practical answer is if you want more unattended run time, simply figure out how long a bottle will last, divide your desired run time by this and that's how many bottles you need. I don't care if the 5 bottles in this example all run down together and I can't see what the advantage is by adding a bunch of expensive crap to the system to make the bottles run down one at a time. You have way more flexibility and control with a manual change system.

Bottom line- it's an age old problem, no matter what system you have, getting the operators to change the bottles when they're supposed to is the biggest challenge.




Chris Krug

http://krugtech.com/

Maximum Up-time, Minimum BS

 

[MacGyverS2000]

Krug,

I see no problems with using an auto system for the exact reason Foo mentions... if the bottle currently being used is getting low (but not out), having the auto system switch over to a new bottle during the weekend is a great saver. When the weekend is over, replace the empty bottle. No hiccups.

You say run 5 bottles together, but then follow it up by saying you don't care if all 5 run down together... that doesn't solve the issue mentioned if all five run down over the weekend. I fail to see what flexibility/control you give up by using an auto system...

Dan - Owner

http://www.Hi-TecDesigns.com

 

[krugtech]

MacGyverS2000- What exactly can you do with an auto change system that has 2 bottles verses having 2 of the same size bottles on a manual system?

There's 2 bottles regardless. On the manual system, just turn both bottles on for a long uninterrupted run. X amount of gas will run the machine for X amount of hours no matter what system you have. When the gas runs out, the machine stops no matter what system you have.

How would you feel about having 2 gas tanks in your car with an auto switcher? What exactly is the point? How about 10 little gas tanks that switch whenever? A huge tank with a working gas gauge is the answer, the only reason they use multiple tanks in a vehicle is because available space dictates this.

What are we trying to achieve here? We want to run the machine for as long as the tanks allow, we want to change tanks without stopping production, we want the operator to be aware that the tanks need attention before it gets to the point where the gas completely runs out and stops production. How does an auto switch system help?

Chris Krug

http://krugtech.com/

Maximum Up-time, Minimum BS

 

[MacGyverS2000]

Not sure how much more clear of a scenario I can come up with than not having to stop an automated system on a weekend to swap tanks...


Dan - Owner

http://www.Hi-TecDesigns.com

 

[krugtech]

I agree 100% on keeping things running but why do we need to swap tanks in the first place? With a manual system, just turn on both tanks and start the machine. No swapping over the weekend needed. How it runs when you shut the lights off friday is how it will run all weekend, no fear of an auto changing system screwing up, no chance of an untried bottle of gas being thrown into the equation 8:00 saturday night.

What could possibly be more reliable and predictable?

Again- The time the machine will run before the gas gets low is dictated by how much gas is available to the laser. A manual system as well as an auto system can supply a laser with gas, without intervention, until ALL the gas bottles on that circuit become low.

If you want the machine to run twice as long, put 2 bottles on it and turn them both on. When you get a low gas warning, shut them off one at a time and change them without interrupting production. Why on earth would anyone want to make it more complicated than this?

Unneeded whistles and bells are unneeded whistles and bells.


Chris Krug

http://krugtech.com/

Maximum Up-time, Minimum BS

 

[MacGyverS2000]

So now you have two bottles that are approaching empty coming into the weekend. No one wants to waste the gas that's in them as they'd get another day's worth of work out of them, but using it up means you have to swap in the middle of the weekend. So let's add in a third tank... and it's the same situation.

The idea is to isolate the low tank from the system, and once it has been used up completely, there's a full tank ready to be switched in without intervention.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[krugtech]

If you have 2 bottles that are approaching empty coming into the weekend, you can rest assured you will run out of gas regardless of what type of system you're using. If you have an isolated bottle that's say half full, regardless of what type of system you have, it will run for 75% as long as if you had 2 full bottles as opposed to a half full and full bottle.

This is the beauty of a manual change system. During the normal work week, the procedure is to have one bottle running and the other tagged "full" but shut off. No "empty" tags are allowed as empty bottles need to be moved to the dock or wherever, not tagged "empty". This mode allows isolating the empty tank if that is what's needed.

When the in use bottle is low, on a manual change system the operator gets a gas warning through the lase control and has to go and switch bottles manually within an hour or so. The main point here, is the operator is aware the first bottle ran out and he can simply change it when he gets time while it runs on the backup bottle. With an autochange system, when he gets a warning from the laser, both bottles are low and need to be changed which would be more likely to interrupt production. The operator never new the gas changed and didn't know he needed to get around to swapping an empty bottle. OK, lets put warning systems on the auto change system, a couple thousand dollars later you really complicated the hell out of it and now were back to pretty much how the manual system would behave with no real benefits. Sure, the operator has to turn a valve with the manual system but for the money, performance and reliability, I'm sure learning to turn a valve wouldn't be a problem.





Chris Krug

http://krugtech.com/

Maximum Up-time, Minimum BS

 

[Foostrap]

I still think an automatic switching system has benefits when running automation, or whenever the machine needs to run unattended.
What is the purpose of an automatic laser gas switching system? I see it as allowing you to minimize gas waste (run bottle as low as possible) without production interruption.
It’s not about how long you can run without having to swap bottles. Even a half full bottle will allow you to run thorough the week-end with no problem. The issue arises when the bottle gets low, yet not completely low. What do you do then if you need to run the machine unattended? Do you switch to a full bottle before leaving, wasting the left over gas in the previous bottle (you could re-use that bottle later, but keeping track of what bottle is full, half full, almost low, completely low may complicate everything)?
Or do you leave it as is, risking production interruption if the bottle gets empty and nobody is around?
Connecting 2 bottles in parallel doesn’t fix this problem; it only delays it. Eventually those 2 bottles will run low; and what do you do then if you need to run unattended? Waste 2 bottle gas left overs? (Not to mention when you have a bad laser gas bottle, you now cross contaminated 2 bottles).

So, this is when the automatic switching system is great. You only need 2 bottles on site; one in use, one as your backup. When one is empty, you now run with a full bottle, giving you plenty of time to order the next bottle. Bottles are run to the end, always. No waste. No production interruption. Easy for the operator. It doesn’t get any better than that.

Concerned about cost; get a semi-automatic switching system; that’ll do the job as well. Even better, if you’re going to spend $500,000 for a laser cutting machine with automation, I’m sure you can negotiate with the manufacturer to have the automatic system thrown in for free.

 

[krugtech]

let's stake it one step at a time- tell me one, just one advantage of the auto change system and I'll tell you why is't not worth it. As far as the last post.

As far as cross contamination- if the system is set up properly this can't happen. The system is really simple, a regulator fed off a T with 2 high pressure whip lines. The fittings that screw into the cylinders have check valves in them so gas can only come out.

It's like this, if you really want to control the gas going into the machine, use the manual system, yes it's slightly more complicated, but it can do everything an auto system can do plus more. If you want it as simple as possible for the operator and don't want to be concerned about the laser gas supply then maybe the expense of an auto change system is justified.

I've been doing this for over 24 years, short of pouring the gasses into the machine with a funnel, I've seen just about every setup under the sun and I've seen the trouble they've caused.

Chris Krug

http://krugtech.com/

Maximum Up-time, Minimum BS

 

[Foostrap]

Ok, I understand you like the manual system. The semi-automatic system can also operate as manual system by the way. So any advantages you see in your manual system, the semi-automatic system also has them.
What is the advantage of the automatic system? You can run your bottles always to the min limit with no one on site and no production interruption.