Funny gas story
Funny gas story
(OP)
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.....
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





RE: Funny gas story
http://www.specialtygasreport.com/features/361
Chris Krug http://krugtech.com/
Maximum Up-time, Minimum BS
RE: Funny gas story
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RE: Funny gas story
RE: Funny gas story
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
RE: Funny gas story
RE: Funny gas story
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
RE: Funny gas story
RE: Funny gas story
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
RE: Funny gas story
RE: Funny gas story
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
RE: Funny gas story
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
RE: Funny gas story
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
RE: Funny gas story
Dan - Owner

http://www.Hi-TecDesigns.com
RE: Funny gas story
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
RE: Funny gas story
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
RE: Funny gas story
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
RE: Funny gas story
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.
RE: Funny gas story
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
RE: Funny gas story
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.
RE: Funny gas story
With a manual system, you can run your bottles always to the min limit with no one on site and no production interruption. I know how to do this, it's pretty simple.
If I had a choice between the most reliable gas system and a system that was a little easier to operate, I would go reliable. Supplying good gas to the laser is way more important than making things slightly easier for the operator to get every last drop of gas from the cylinder.
I have seen auto change systems take machines out of lights out. production when they switch to a bad bottle of gas. I have never seen a manual change system do this. What's more important, getting all your lights out production or making life a little easier for the guy who is responsible for the gas.
Most of the lazy-ass button pusher operators like the auto change systems, they like really complicated machines with loads of whistles and bells, these unnecessarily complicated machines are a warehouse full of reasons to screw off and not get work done. Most of the responsible operators like the manual system, they like to have the control they need to insure no interruption in production. Common sense really helps keep the lasers running.
While we're on the subject- What would you consider a safe minimum limit?
Chris Krug http://krugtech.com/
Maximum Up-time, Minimum BS
RE: Funny gas story
To remove the empty bottle and install a new one, the operator first needs to manually rotate a level; this will reset the pressure differential; the backup bottle then becomes the primary bottle.
There are no electronics involved (unless you want the alarm box to warn when one of the 2 bottles is low). It is therefore very reliable. To operate it as a manual system, just leave the backup bottle closed. You can then control exactly when you want to engage the second bottle just like a manual system.
I agree with you, I would choose reliability over simplicity of use. But why compromise when you can have both.
And I agree that a manual switching system is fine for standalone lasers. But for machines with unattended operation, a system switching from one laser gas bottle to the next with no operator intervention is better. It seems you are saying this is causing problems with resonators working with 3 bottles. I am not familiar with those, so I am not aware of this. I only work with Fanuc resonators which use 1 bottle of premix. When you have a bad laser gas bottle, it's pretty simple. You swap just one bottle and you're good to go.
If you get an alarm that could be related to bad laser gas, it's easy to look at the laser gas switching system. If it is pulling gas from the reserve and if the primary bottle is empty, it's pretty simple to deduct that a changeover occurred and the resonator is now supplied from a new bottle.
I don't understand your point saying that this would never happen with a manual system. If you have a bad laser gas bottle, switching to that bottle automatically or manually will give you the same result. How can you tell a laser gas bottle is bad before using it?
RE: Funny gas story
Looks pretty pricey to me.......
Don't forget about what I said about a bad gas bottle being switched into the system on Saturday night unattended, with unattended being the keyword here. That could never happen with my system. aka the system with 1/3 the parts..... sounds 3 times more reliable to me.
Chris Krug http://krugtech.com/
Maximum Up-time, Minimum BS
RE: Funny gas story
As far as shutting down production due to a bad bottle; sure that'll never happen if you never switch to a bad bottle.
So, how again do you handle a case where your bottle is running low (but not completely low), and need to run for the week-end?
RE: Funny gas story
"So, how again do you handle a case where your bottle is running low (but not completely low), and need to run for the week-end?"
uhhh, I open the valve on the backup bottle. I know this is extra work but it's really worth it.
I would open the backup bottle about an hour before I went lights out. It will start flowing into the laser right away and if after an hour, if it doesn't fault out you can rest assured the bottle is OK. OR you can autochange Saturday night to a possibly bad bottle and get a suprise monday morning.
Apparently on Monday morning having 2 bottles that are both partially empty on the machine appears to be a real real big problem but I don't know why. Just shut one off, run the other until it needs to be swapped and replace it with a full one. No rocket science here.
Chris Krug http://krugtech.com/
Maximum Up-time, Minimum BS
RE: Funny gas story