The Difference Between LP and HP

[NAM001]

This makes no sence at all. Any 300 bar whip can fill a 200 bar VALVE. So long as the proper valve ois on the tank there should not be problems. all my tanks have 200 bar valves on them. my whips are 300b as is my regulators. The protections are for the devices not the tank. The idiot proofing is to prevent a say 100 bar device from being pressuurized from a 300 bar source. Notice you dont have yolk converters for 300 bar valves.

So your 300 bar whips can be used directly for filling a tank rated for 200 bar? :buggy: That's very strange for me. Unless I tamper with the whip valve, I physically can't fill my 200 bar tank without a 300 to 200/232 bar adapter (which is equipped with a 235 bar safety valve). I guess it's an attempt at idiot-proofing the hardware; I wouldn't like being close to a 200 bar tank which some idiot had filled to 300+ and then left in the trunk of a car standing in the sun...

 

[kwinter]

.
We do have burst discs, but it is very common to either plug them....

I can't believe you actually posted this.


iPhone. iTypo. iApologize.

 

[tbone1004]

why? it is extremely common to do one of those two things, some people plug them using the reasoning that Europe doesn't believe in them and the hydro pressures are around where the compressors can fill to anyway, on LP tanks, and nowhere near where most of them can fill to on the HP tanks, or they will take LP tanks and put burst discs somewhere around their hydro pressures, so they can get those 3800psi fills to cool down to 3600, it's a fact, whether you like it or not it happens regularly, and whether I post it or someone else does it was going to come up.

 

[Redshift]

In Europe we don't use burst disks, but also don't overfill the tanks (except a bit, maybe less than 10% when filling so it cools down to its work pressure).

 

[kwinter]

I had a burst disk go in the car one time on a set of double HP120s. I thought I had been shot. I'm sure I left a stain on the seat. The tanks had been packed the night before and then I decided not to leave until morning. Hot, hot, hot. That's what will increase the pressure. It's not a matter of overfilling.
Except yes, it is. I remember the other time. A low pressure 120 being filled with O2 and the gas jockey doing the boosting went way too fast. He brought the tank to the front of the shop and I burned my hand on the valve. As I rushed to the back to get a wet towel to throw on the valve, the disk went. And so did 120 cubic feet of oxygen.
Would I have been safer in those 2 circumstances with a plug instead of a burst disk? I don't really know. But over pressure relief is considered a safety feature and is required.
All that being said, I know plenty of folks that double disk. But they don't post about it on a public forum.


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[A. Dale Fox]

In SCUBA cylinders HP and LP cylinders are only marketing terms. The fact is that both are high pressure cylinders and the CGA and DOT classify steel cylinders as High Pressure when their service pressure is 900 psig or greater. Aluminum cylinders are different in that CGA and DOT consider them Hige Pressure when their services pressure is 1800 psig or greater.

 

[Redshift]

If by marketing you mean that these terms were introduced as a way to serve the market where they are being used, then I agree. What the DOT says or don't does not mean a thing for divers. We want to know the pressure of a cylinder and this nomenclature helps (a bit more in Europe than US, I guess...). They have a meaning and there are differences between the two types of cylinders, that's what's important. Of course they are all high pressure when compared to atmospheric pressure or the pressure of a car tyre...

 

[KenGordon]

This makes no sence at all. Any 300 bar whip can fill a 200 bar VALVE. So long as the proper valve ois on the tank there should not be problems. all my tanks have 200 bar valves on them. my whips are 300b as is my regulators. The protections are for the devices not the tank. The idiot proofing is to prevent a say 100 bar device from being pressuurized from a 300 bar source. Notice you dont have yolk converters for 300 bar valves.

Read this DIN Scuba Fittings, there is more to 300 bar fittings than the seven threads. There is a different sized projection on the end to prevent 300 bar whips fitting into 200 bar cylinders. Regulators don't have that. My transfilling whip doesn't either so if I can move gas from a 300 bar source into a 232 bar destination. I guess your compressors have a fitting like that rather than a 'proper' one like stoker's club.

 

[Diver0001]

I am looking at tanks. Some tanks say LP Low Pressure...others say HP High Pressure.
What's the difference and is here a benefit to either one?
Thanks

I think you have the answer to your main question already. Let me add to this by saying that there are regional differences as well.

For example, I dive in the Netherlands with 2x12 litre steel Faber cylinders for back gas and some kind of aluminium cylinder(s) for deco.

a 12L Euro cylinder is about equivalent to a steel 100cf cylinder in the USA. When I was there on vacation some time ago I borrowed a set of steel 100cf doubles for a few dives and found them to be a LOT more negative than I was anticipating. Turns out that just like American cars are big, heavy and over-engineered, scuba tanks are too. European cylinders may not even be legal in the USA due to being too light for the pressures they have to hold.

R..

 

[Storker]

Read this DIN Scuba Fittings, there is more to 300 bar fittings than the seven threads. There is a different sized projection on the end to prevent 300 bar whips fitting into 200 bar cylinders. Regulators don't have that. My transfilling whip doesn't either so if I can move gas from a 300 bar source into a 232 bar destination. I guess your compressors have a fitting like that rather than a 'proper' one like stoker's club.

Thank you for that link. I'm away from my books and my google-fu failed me, so I was close to doubting what I'd been taught.


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