Winter is coming. Watch out "Thermal shock" on laser tube

[Tech_Marco]

Most of you may think that cooler is better for a laser tube. Well, yes or no. There is always a limitation and we should go after an extreme in either case.

First, never drop the temperature below the dew point because if you do that, water condensation may happen

Second, do not operate a laser tube in full power without a minute or two to warm it up if room temperature is low like at the range of10~15'C. Actually I don't suggest anyone operate a laser tube at that low temperature. Why? Thermal Shock!

Last week a customer emailed me and reported that his 720mm 32W tube cracked. He insisted that water was running. I asked him what was the room temperature there and was told that it was about 15'C. He was firing it up in full power for cutting and in 1~2 minutes, he heard cracked sound from the tube. He found that water filled up the inner tube of the laser. I told him that he should warm it up before fire in full power at such lower temperature.

Anyway, I sent him another tube the next day. It was not really his fault so warranty will cover this 'mistake'


Marco

[DonL]

Most of you may think that cooler is better for a laser tube. Well, yes or no. There is always a limitation and we should go after an extreme in either case.

First, never drop the temperature below the dew point because if you do that, water condensation may happen

Second, do not operate a laser tube in full power without a minute or two to warm it up if room temperature is low like at the range of10~15'C. Actually I don't suggest anyone operate a laser tube at that low temperature. Why? Thermal Shock!

Last week a customer emailed me and reported that his 720mm 32W tube cracked. He insisted that water was running. I asked him what was the room temperature there and was told that it was about 15'C. He was firing it up in full power for cutting and in 1~2 minutes, he heard cracked sound from the tube. He found that water filled up the inner tube of the laser. I told him that he should warm it up before fire in full power at such lower temperature.

Anyway, I sent him another tube the next day. It was not really his fault so warranty will cover this 'mistake'


Marco

What was his water temp? 15 Degrees is not very cool, a water chiller in a room that is 15degrees may haul the water temp down a lot and then I could see a crack from thermal shock. My laser is in a room that is usually at 18 degrees and could easily go below to 15 but the water temp is the same and I only apply cooling to the water when it rises above 21 degrees c... We go out wearing a T shirt and shorts in 15 degree weather Not kidding, Last Saturday it was 9 degrees C and hundreds of people were out on motorcycles enjoying the weather... We are usually at -15 degrees c and 70 cm of snow on the ground by now...

Anyway What is the recommended operating temperature (Room temp and Coolant Temp) between What min - Max ? I will apply heating or cooling appropriately



Thanks...

[Techgraphix]

In summer i can reach 18 degrees Celsius in my workshop but normally it is 12-15 degrees only (with the radiator on).. that's why my cooling is set to 15 degrees, same as the room-temperature..

Kees

[DonL]

In summer i can reach 18 degrees Celsius in my workshop but normally it is 12-15 degrees only (with the radiator on).. that's why my cooling is set to 15 degrees, same as the room-temperature..

Kees

The RECI website has these specs:
Operation conditions Water cooling: using purified water; 2 to 5 liter/minute; water temperature: 10℃-40℃.
The operating environment: temperature 2-40℃; humidity 10-60%.

[Tech_Marco]

Best temperature is 21~23'C. Tube works for any temp, even 50'C. But....who knows what will happen.

It is not necessary a tube will crack at 15'C or lower. Someone told me that he could drive it down to 10~12'C. Well, good luck.
The only thing I know was that a $2200 Reci tube (150W) cracked in 10min when operate in full power at 15'C. A case happened in Germany.

I always joke with my friends: "When 'no-luck' meets with 'Bad timing' and join 'In perfect', expect to see 'Disaster' in the party "

Marco

[Tech_Marco]

The RECI website has these specs:
Operation conditions Water cooling: using purified water; 2 to 5 liter/minute; water temperature: 10℃-40℃.
The operating environment: temperature 2-40℃; humidity 10-60%.[/quote]


Well, if you tell me that you're going to operate a Reci tube over 30'C, then I won't sell you a tube.
Or, if you tell me that you're using a water radiator to cool off a Reci 80W tube or higher power, I'll be nicely to ask you to buy from other party.


Marco

[DonL]

The RECI website has these specs:
Operation conditions Water cooling: using purified water; 2 to 5 liter/minute; water temperature: 10℃-40℃.
The operating environment: temperature 2-40℃; humidity 10-60%.

Well, if you tell me that you're going to operate a Reci tube over 30'C, then I won't sell you a tube.
Or, if you tell me that you're using a water radiator to cool off a Reci 80W tube or higher power, I'll be nicely to ask you to buy from other party.


Marco[/quote]

Fair enough, I am only quoting the Reci website, I expect that the extreme ranges are not desireable, and you know more about this stuff than I do.

I am a novice so I want to be kind to my equipment.

The RECI website is giving a wide temperature range but is obviously too wide for safety of equipment.
What temperature range would you recomend?

[Tech_Marco]

21~25'C seems the best. 10~12L/m water flow should be good enough (horizontal level).

Reci should be operated at 28mA or less. In fact, keep it at 25mA can last longer. 25mA you only lose less 10W power in general.

Marco

[SWMS]

This is one of the reasons I have opted for a Teco aquarium chiller. It has a heater and uv bulb to kill any algae. Start it up and let he chiller heat the water then the heater will switch off and the chiller will keep the water cool when the laser is operating. I'm using it with a 25 litre drum as a buffer.