200 Bar (3000 psi) while the cylinder can be filled only 139 Bar - fully?

[Dory]

Who can explain me what is the sense in the pressure gauge that it shows 200 Bar (3000 psi) while it can be filled only 139 Bar totally?

 

[MonkeyArrow]

Assuming that you are talking about oxygen cylinders and their gauges, extra PSI/BAR is shown to ensure that you are not overfilling the cylinder. If the cylinder was filled beyond its capacity, lets say 200 BAR, but you only had a gauge that showed pressure up to 139 BAR, then you would never know that your cylinder is overfilled. That is a safety issue as the cylinder and its components (gauge, regulator, tubing, etc.) are not meant to handle pressures that high. Therefore, by not knowing that your cylinder is over-filled, you could have a catastrophic failure of the cylinder leading to injury or death (think about a grenade exploding).

 

[Dory]

It begin to make sense.
But I thought that the maximum Bar that the cylinder can contain is near to the 139 - for instance 145 Bar at the most. I've never thought it can be 60 Bar more the safety use. It's interesting.

 

[Dory]

begins*

 

[gotbeerz001]

It begin to make sense.
But I thought that the maximum Bar that the cylinder can contain is near to the 139 - for instance 145 Bar at the most. I've never thought it can be 60 Bar more the safety use. It's interesting.

Gauge manufacturers make gauges.
Bottle manufacturers make bottles and buy a gauge that fits the need.
Probably cheaper to simply buy a 200 bar gauge and say "don't fill over 139" than to pay to have special 145 bar gauges made.

Same thing on fire engines where manufacturers have a compound gauge (pressure/vacuum) as a discharge gauge when there is no chance for it to ever read vacuum. It is simply cheaper to buy one gauge in bulk that will work for both intake and discharge gauges than to buy separate gauges which are more ideally suited but cost more.

As for the safety feature, they will include an appropriate burst disc to prevent overfilling.

 

[ThadeusJ]

Carbon fibre cylinders can be filled to a higher pressure than aluminum or steel.

 

[Akulahawk]

With pressurized cylinders, I would have to say that I would most definitely want a gauge that can read higher than the rated pressure of the cylinder so that I could/would know if the cylinder was filled to the appropriate pressure, was under-filled, or was over-filled (safety concern). While burst discs are installed to prevent catastrophic failure of the cylinders, those discs might not burst at the designed pressure or the cylinder may actually not be quite as strong as expected and fail "early" or may fail from fatigue due to repeated filling/emptying.

 

[samiam]

Carbon fibre cylinders can be filled to a higher pressure than aluminum or steel.

I have never seen one of thoose! Now I want one! I can get carbon fiber accents on my car and then mount a dope carbon fiber o2 tank! I imagine they are not as effective for taking down a combative assailant. Nothing quite like rounding a corrner to a steel o2 tank in the face.

 

[MonkeyArrow]

I have never seen one of thoose! Now I want one! I can get carbon fiber accents on my car and then mount a dope carbon fiber o2 tank! I imagine they are not as effective for taking down a combative assailant. Nothing quite like rounding a corrner to a steel o2 tank in the face.

They use carbon fiber cylinders for SCBA tanks exclusively.

 

[ThadeusJ]

I looked up the Luxfer site (Look here) and they claim that their alloy cylinders wrapped in carbon fibre were initially adopted by firefighters but are now being used by paramedics and first responders. 3000 psi and weighing in at 3 lbs for 436 L cylinder.

 

[chaz90]

I looked up the Luxfer site (Look here) and they claim that their alloy cylinders wrapped in carbon fibre were initially adopted by firefighters but are now being used by paramedics and first responders. 3000 psi and weighing in at 3 lbs for 436 L cylinder.

Yeah, we exclusively use these at my service since all gear has to be portable without having an ambulance available. They work well and are super lightweight. We only fill them up to ~2200 PSI, but they're rated for more.