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]

What is a "semi-automatic" system and how does it differ from a manual system and automatic system?

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

 

[Foostrap]

What I mean by semi-automatic is a system based on differential pressure (see picture). The system has 2 internal regulators; the one for the primary bottle is set slightly higher than the one for the backup bottle. As the primary bottle in use gets low, the pressure at the primary regulator will drop, until it reaches the pressure from the backup bottle regulator. At that point, gas starts to flow from the backup bottle.
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?

 

[krugtech]

holy crap! it looks like you have 3 regulators just for one gas channel! 3 regulators and enough parts to make a still! so I need 9 regulators and all that other stuff to get me what exactly?

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

 

[Foostrap]

I'm only familiar with 1 premix bottle resonators; you only need one of those in that case. So price difference between manual and auto is not huge.
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?

 

[krugtech]

"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

 

[Foostrap]

OK, I understand. I guess if you don't mind having to plan ahead before leaving for the night (on top of everything else you need to plan for your week-end run), and if you don't forget to test your gas before leaving (which I guess you could also do with an auto system); if you don't mind having bottles around that are low, half full, full or anything in between. If your operator is organized enough to keep track of those bottles, then sure, your system seems like ideal. For everyone else, the automatic system is better.