How you setup a laser tube to avoid water bubble

[Tech_Marco]

Hi:

Recently I received a few report of broken laser tube and all happened to the Reci 80W and 130W. Some bought from me while some bought from other parties. I have tested a DC water pump yesterday to my customer and I found something important. So, I'd to share with you folks here.

I have setup a F4 tube (100W) 5ft above the ground. I tried two DC pumps: 8.3L and 10.0L . There was no trouble for a 8.3L pump to lift water at 5ft high but I found something that I was not really happy to see happening; water couldn't filled up the tube completely but 10~15% left for air or bubble. I turned the tube clockwise and counter-clockwise trying to to get the bubble to be pumped out. Occasionally, I have to squish the water tubing to create 'sudden pressure' to help for the suction. It helped but... I really didn't expect a customer would like to do it every time they're using the machine. So, I was thinking that the pumps were not powerful enough. Then I swapped a 10.0L pump and ... happened the same!

I was thinking "Shoot, do I need bigger pump like 15L or 18L?". Then I observed something a little odd. I saw that the tube was not in horizon but with about 10 degree slop down to the water-out side. Hmm..... that could lead to the problem I guess. So, I raised up the other end of the tube and allow about a little up-slop. Now. it seems working and I saw rapidly water flow movement happened right at the moment I raised up the tube. But there is one more issue. There were a few big bubble couldn't escape from the tube. I turned the tube in two direction and in a sudden, all bubbles sucked out so quick! Bingo! Now I saw what's happening. The outlet tubing (glass hole) must be on the top of the laser tube or bubble couldn't escape from the tube. Little thing but extremely important! If there is a big bubble exist to the two pole; anode and the cathode, the chance of having cracking tube or damage pole is very significant.

So, when you setup a laser tube, do three things before close the cover:
1) make sure the tube is level or with 2~3 degree up
2) make sure the outlet hole is on top of the tube but not facing sideways or downward
3) test the pump and make sure no water bubble (I mean the big one) stuck inside of the tube

Have a great day and play safe

Marco