I like to drop off my HP steel tanks at my LDS on Day One and pick them up on Day Two. They know to let them cool overnight and top off in the morning. By the time I pick them up on my lunch hour, it's a quick pressure check and possible top off.
I personally get overpressured (around the collar) when I take my steel 232 bar tanks in to fill and find that when i get them back they are just under 200 bar (or 15% less than thier working pressure) - happens pretty frequently and rather annoying, I'm happy to pay a buck or 2 more for a 230 bar fill but don't underfill. I've purchased steels for a reason and it's not to look cool, I'm an airpig and happy to admit it, I don't want to cut my dive short because the fill attendant was in a hurry or couldn't be bothered checking the pressure a couple of hours after the initial fill - I do leave my tanks at the dive store for a week between dives. #askmark
If you leave them for a week I'd specifically mention that you want them topped up. Have a talk with the blender. Most dive centers I know will do this automatically if you give them time. They should also have no problem with you testing the pressure in store and asking them to top it up when it's low.
Yup, most divers don't think about the shift in temp jumping into water and how that may affect your cylinder pressure. If you have a transmitter and look back at the air consumption in the logbook you'll often see a spike right at the start of the dive.
Filling and waiting. No problem. I'll just take my mandatory after dive decompression coffee even when not having dived. Then proceeding to check out the new stuff that came in or pet the shop dog. Mostly the latter.
I was at a dive center once and they just put the tanks into a big water bucket while filling them up. That way the tanks were directly cooled down while filling. Does not seem to be a common practice but made sense to me regarding over-filling and putting stress onto the tank.
Yeah, we used to have dunk tanks at one of my dive centres. It helped with the cooling and you could easily see leaks earlier. There were a few downsides and I lost count of the number of times I was soaked with an extruded O-ring. I did hear that there was some ambiguity over the temperature imbalance on the inside and outside of the wall that may weaken it. I'm not sure how accurate that is.
I am the person whose cylinder is first at 50 bar. In the diving boat, I ask that they put more air in my bottle so that I won't be a burden to others in the same group. So when others have maybe 190 bar, I have 210 bar.
210 bar is fine for an 11.1L alu. Their working pressure is 207bar. If you fill it to 220 in one go and let it cool it'll end up around 180-190. If you then top it up again to 220 and let it cool you'll get about 210. As a cave diver we also prefer fills to 210+ bar since that number is easily divided by 3 giving us 70 bar to enter, 70 to exit and 70 in reserve. If you get a 205 bar fill we round down to 180 so you get 60 bar to enter.
#ASKMARK Isn’t there a way to stick a digital temperature probe on the tank thats wired into the “system” such that you could set a target pressure and the system would overfill to a pressure that would then cool to the working pressure?
It depends on the panel but it's probably easier and cheaper just to get a Dive Master to fill cylinders. Most filling stations I've worked with are all manual valves and need a _skilled_ hand to open and close at the right time. Theoretically yes, you could certainly automate things with temperature and pressure sensors but, we rarely fill one cylinder at a time and rarely directly from the compressor. I don't trust too many automations where things can go bang. Sure there's an argument for keeping people away from something that might go bang but, I'd prefer to watch the gauges and be right there to close valves
when i was a kid i used to go on holidays with my dad who was a bsac national instructor so all holidays where dive holidays everywhere we used to go spain ,south france or malta i used to see tanks getting filled underwater mostly in a proper built small pool that could fit max 3 or 4 tanks.since diving myself (just a fare weather diver so just on holidays) i can`t remember seeing any getting filled this way. is this just procedures worked out to include the heat in the pressure or was it that it was a bit more cowboy back then and some tanks could exploded as they just filled the hell out of them ?
There's a cave dive center in the Lot in France that fills tanks in a refrigerated water tank. That works because they don't have to wait for the tank to cool and top up, but only because they're actively removing heat and because the temp difference is larger. Filling in a room temperature tank doesn't remove as much heat so the effect will be reduced quite a bit. Also people used to think the water would cushion an explosion if the tank burst. But it's been shown that doesn't really work. Maybe that's why most stopped doing it?
Yeah, we had dunk tanks to fill cylinders at one of my dive centres. They helped with the cooling, you could easily see leaks earlier and if one decided to go bang the water and walls should help to protect people around it. There were a few downsides like cleaning the tanks, customer's cylinders were always wet, the floor was always wet and I lost count of the number of times I was soaked with an extruded O-ring from an A-Clamp. Somebody told me that the heat inside the tank and cool outside could affect the strength of the cylinder wall but, I don't know how accurate that is...
One of my local dive centers loves to overfill my LPs. They're rated to 2400+ psi but I've gotten them a couple times filled to over 3000. I never found out if they overfilled on purpose or just weren't paying attention. I know a lot of people like to overfill LPs, but I wonder if people really overfill them by that much?
Overfilling that much shouldn't happen by accident. There are different fill hose connecters for higher pressure rated tanks that don't fit on lower pressure tank valves. The lower pressure fill hoses should also have a safety valve inline that prevents them being overfilled by much. But of course every dive center can build their fill station their own way...
Unless you're filling the cylinder, overpressure doesn't present any risk (although I guess if you smash the valve, à la Mythbusters, the extra pressure makes it a tiny bit worse). If you own the cylinder, and you regularly see this, you might want to have a wee chat with whoever is providing your fills, as "stretching" it regularly might lead to a fail at the next test.
If it's about 20c outside - you fill it to 3170 , it will be 3000 when it cools down. Don't ask me how i know, we always stick to rules 😂😂 ---- If you leave full cylinder in the car on a hot summer day - pressure will go up to about 3200. There is a bit of wiggle room built in, so it will not fail. But what will happen more likely is the burst disk poping , and it's a bit embarrassing to have a tornado in the back, specifically if you have a child daycare on the other side of your wall 😂😂
#askmark Maybe someone already asked you, but it just come into my mind, if a tank is build for 300 bar, why did the just fill 230 bar max? I remember when I was at Volunteer Fire Brigade we had always 310bar. So I just wonder, because I guess those 70-80 bar more could count on a dive. I would guess at least 5 minutes more.
Not all tanks are created equally. There are 300 bar working pressure tanks available that will be tested at 450 bar. Not all filling stations will have a compressor capable of filling them to 300 bar though.
You need that margin because an exploding tank can kill someone, because the pressure may rise due to the tank being left in the full sun, because the inside walls of the tank may be corroded due to water and many other reasons, because some people rarely have their tanks inspected. In other words, the tank needs a good margin of safety. There are specific tanks made for 300 bar fills. They'll be built with thicker walls and be tested to even higher pressures.
I like to drop off my HP steel tanks at my LDS on Day One and pick them up on Day Two. They know to let them cool overnight and top off in the morning. By the time I pick them up on my lunch hour, it's a quick pressure check and possible top off.
That's the way to do it. Plenty of planning and you get the correct fill
I personally get overpressured (around the collar) when I take my steel 232 bar tanks in to fill and find that when i get them back they are just under 200 bar (or 15% less than thier working pressure) - happens pretty frequently and rather annoying, I'm happy to pay a buck or 2 more for a 230 bar fill but don't underfill. I've purchased steels for a reason and it's not to look cool, I'm an airpig and happy to admit it, I don't want to cut my dive short because the fill attendant was in a hurry or couldn't be bothered checking the pressure a couple of hours after the initial fill - I do leave my tanks at the dive store for a week between dives. #askmark
If you leave them for a week I'd specifically mention that you want them topped up. Have a talk with the blender. Most dive centers I know will do this automatically if you give them time. They should also have no problem with you testing the pressure in store and asking them to top it up when it's low.
I would say Yes. I had a SpareAir 6cf Tank O-Ring fail. Fortunately it wasn't in the water
thanks for the info about air loss at the beginning of a dive. i just figure i was breathing heavily at the beginning of a dive.
Yup, most divers don't think about the shift in temp jumping into water and how that may affect your cylinder pressure. If you have a transmitter and look back at the air consumption in the logbook you'll often see a spike right at the start of the dive.
Filling and waiting. No problem. I'll just take my mandatory after dive decompression coffee even when not having dived. Then proceeding to check out the new stuff that came in or pet the shop dog. Mostly the latter.
I was at a dive center once and they just put the tanks into a big water bucket while filling them up. That way the tanks were directly cooled down while filling. Does not seem to be a common practice but made sense to me regarding over-filling and putting stress onto the tank.
Yeah, we used to have dunk tanks at one of my dive centres. It helped with the cooling and you could easily see leaks earlier. There were a few downsides and I lost count of the number of times I was soaked with an extruded O-ring.
I did hear that there was some ambiguity over the temperature imbalance on the inside and outside of the wall that may weaken it. I'm not sure how accurate that is.
What do Florida cave divers love most about scuba gear?
The turnaround pressure is stamped right on their tanks!
I am the person whose cylinder is first at 50 bar. In the diving boat, I ask that they put more air in my bottle so that I won't be a burden to others in the same group. So when others have maybe 190 bar, I have 210 bar.
Could you not use a 15 litre cylinder? 😮
@@paultyler4001 Diving trips with rental cylinders in Thailand. There is only one size in the boats. 11.1 liters.
210 bar is fine for an 11.1L alu. Their working pressure is 207bar. If you fill it to 220 in one go and let it cool it'll end up around 180-190. If you then top it up again to 220 and let it cool you'll get about 210.
As a cave diver we also prefer fills to 210+ bar since that number is easily divided by 3 giving us 70 bar to enter, 70 to exit and 70 in reserve. If you get a 205 bar fill we round down to 180 so you get 60 bar to enter.
#ASKMARK Isn’t there a way to stick a digital temperature probe on the tank thats wired into the “system” such that you could set a target pressure and the system would overfill to a pressure that would then cool to the working pressure?
It depends on the panel but it's probably easier and cheaper just to get a Dive Master to fill cylinders. Most filling stations I've worked with are all manual valves and need a _skilled_ hand to open and close at the right time.
Theoretically yes, you could certainly automate things with temperature and pressure sensors but, we rarely fill one cylinder at a time and rarely directly from the compressor. I don't trust too many automations where things can go bang. Sure there's an argument for keeping people away from something that might go bang but, I'd prefer to watch the gauges and be right there to close valves
when i was a kid i used to go on holidays with my dad who was a bsac national instructor so all holidays where dive holidays everywhere we used to go spain ,south france or malta i used to see tanks getting filled underwater mostly in a proper built small pool that could fit max 3 or 4 tanks.since diving myself (just a fare weather diver so just on holidays) i can`t remember seeing any getting filled this way. is this just procedures worked out to include the heat in the pressure or was it that it was a bit more cowboy back then and some tanks could exploded as they just filled the hell out of them ?
There's a cave dive center in the Lot in France that fills tanks in a refrigerated water tank. That works because they don't have to wait for the tank to cool and top up, but only because they're actively removing heat and because the temp difference is larger. Filling in a room temperature tank doesn't remove as much heat so the effect will be reduced quite a bit.
Also people used to think the water would cushion an explosion if the tank burst. But it's been shown that doesn't really work. Maybe that's why most stopped doing it?
Yeah, we had dunk tanks to fill cylinders at one of my dive centres. They helped with the cooling, you could easily see leaks earlier and if one decided to go bang the water and walls should help to protect people around it. There were a few downsides like cleaning the tanks, customer's cylinders were always wet, the floor was always wet and I lost count of the number of times I was soaked with an extruded O-ring from an A-Clamp.
Somebody told me that the heat inside the tank and cool outside could affect the strength of the cylinder wall but, I don't know how accurate that is...
I would have thought it was the perfect solution to getting the fills correct so would be the norm
One of my local dive centers loves to overfill my LPs. They're rated to 2400+ psi but I've gotten them a couple times filled to over 3000. I never found out if they overfilled on purpose or just weren't paying attention. I know a lot of people like to overfill LPs, but I wonder if people really overfill them by that much?
Overfilling that much shouldn't happen by accident. There are different fill hose connecters for higher pressure rated tanks that don't fit on lower pressure tank valves. The lower pressure fill hoses should also have a safety valve inline that prevents them being overfilled by much. But of course every dive center can build their fill station their own way...
Unless you're filling the cylinder, overpressure doesn't present any risk (although I guess if you smash the valve, à la Mythbusters, the extra pressure makes it a tiny bit worse). If you own the cylinder, and you regularly see this, you might want to have a wee chat with whoever is providing your fills, as "stretching" it regularly might lead to a fail at the next test.
I love that Shirt!! Where I can get it?
Ah, I don't think Fourth Element make it anymore. They made them for the Batman V Superman film. I think it was called the Cave Arrow Tee
@@ScubaDiverMagazine what a pity.. It is really awesome.. But thanks for your faast reply!
If it's about 20c outside - you fill it to 3170 , it will be 3000 when it cools down.
Don't ask me how i know, we always stick to rules 😂😂
----
If you leave full cylinder in the car on a hot summer day - pressure will go up to about 3200.
There is a bit of wiggle room built in, so it will not fail.
But what will happen more likely is the burst disk poping , and it's a bit embarrassing to have a tornado in the back, specifically if you have a child daycare on the other side of your wall 😂😂
#askmark
Maybe someone already asked you, but it just come into my mind, if a tank is build for 300 bar, why did the just fill 230 bar max?
I remember when I was at Volunteer Fire Brigade we had always 310bar.
So I just wonder, because I guess those 70-80 bar more could count on a dive. I would guess at least 5 minutes more.
Not all tanks are created equally. There are 300 bar working pressure tanks available that will be tested at 450 bar. Not all filling stations will have a compressor capable of filling them to 300 bar though.
You need that margin because an exploding tank can kill someone, because the pressure may rise due to the tank being left in the full sun, because the inside walls of the tank may be corroded due to water and many other reasons, because some people rarely have their tanks inspected. In other words, the tank needs a good margin of safety.
There are specific tanks made for 300 bar fills. They'll be built with thicker walls and be tested to even higher pressures.
Another GREAT video!
Great video