The Difference Between LP and HP

[TSandM]

Turns out that just like American cars are big, heavy and over-engineered, scuba tanks are too.

Too funny!

 

[NAM001]

NOthing in your article contridicts what i posted. a 3oo device will connect and function on a 200b valve. The oppolite is not true a 300 whip will connect and seal with a 200b valve a 200 b whip will connect but not seal in a 300b valve. I also see vents in 300bar valves so that once you break seal it allows venting of pressure from the valve.

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.

 

[KenGordon]

NOthing in your article contridicts what i posted. a 3oo device will connect and function on a 200b valve. The oppolite is not true a 300 whip will connect and seal with a 200b valve a 200 b whip will connect but not seal in a 300b valve. I also see vents in 300bar valves so that once you break seal it allows venting of pressure from the valve.

This bit:

"And you remember I pointed out the hole at the back of the DIN pillar valve? Well this is a 300bar DIN filling adapter. It has a tube sticking out that goes into that hole but will not fit the 232bar pillar valve. This is done to try and stop you overfilling a tank way beyond its rated pressure."

 

[NAM001]

Yes i saw it and i have never seen this on any 300b whip in the states. If it does exist in the US it most likely does not anywhere i get a fill from. Not saying you are wrong just that Ive never seen it. Any whip I see is like the 200b but the thread leignth of the 300. It is hard to find a male din that is not 300 bar.

This bit:

"And you remember I pointed out the hole at the back of the DIN pillar valve? Well this is a 300bar DIN filling adapter. It has a tube sticking out that goes into that hole but will not fit the 232bar pillar valve. This is done to try and stop you overfilling a tank way beyond its rated pressure."

 

[KenGordon]

Yes i saw it and i have never seen this on any 300b whip in the states. If it does exist in the US it most likely does not anywhere i get a fill from. Not saying you are wrong just that Ive never seen it. Any whip I see is like the 200b but the thread leignth of the 300. It is hard to find a male din that is not 300 bar.

300 bar cylinders are common enough here to mean that mistaking a 232 for a 300 is not unlikely. I suppose that is less of a problem where you are.

 

[Storker]

NOthing in your article contridicts what i posted. a 3oo device will connect and function on a 200b valve. The oppolite is not true a 300 whip will connect and seal with a 200b valve a 200 b whip will connect but not seal in a 300b valve. I also see vents in 300bar valves so that once you break seal it allows venting of pressure from the valve.

This bit:

"And you remember I pointed out the hole at the back of the DIN pillar valve? Well this is a 300bar DIN filling adapter. It has a tube sticking out that goes into that hole but will not fit the 232bar pillar valve. This is done to try and stop you overfilling a tank way beyond its rated pressure."

I was wondering if we were dealing with a case of

Yes i saw it and i have never seen this on any 300b whip in the states. If it does exist in the US it most likely does not anywhere i get a fill from.

That just shows that anywhere you get a fill from doesn't follow the standards. The standards are given in KenGordon's link, and if the fiil station follows them, you won't be able to fill a 200 or 232 tank with a 300 bar fill whip. At least not without an adapter, which should be equipped with a safety valve.

300 bar cylinders are common enough here to mean that mistaking a 232 for a 300 is not unlikely.

Yup. On more or less every club outing I see a mix of 200, 232 and 300 bar tanks. New(ish) tanks are usually 232 or 300 bar, older tanks are often 200 bar. IMO, the proper design of a 300 bar fill valve is a nice safety feature. IIRC, hydro test pressure for a 300 bar tank is 400 or 450 bar, i.e. max 150% of working pressure. Assuming a similar ratio for lower pressure tanks a 200 bar tank should have a test pressure of 300 bar. So, if you by mistake fill your 200 bar tank to 300, you're walking uncomfortably close to the edge. Particularly if you like to overfill by some 10% to allow for pressure decrease as the tank cools, like I do...

 

[NAM001]

I dont know where you are but i would suspect that we have little if no need for an actual 300 bar fill whip as 232b is aboaut as high as most tanks get filled. I also suspect that the name, as far as fillstations are concerned , 300 is attached to the number of threads and not the whole valve design since actual 300b whips are rare to find in operation. It is generally accepted that 200 and 300 bar devices (valves and fittings) are of the same psi quality but with different safety aspects in the construction. The only constructions ever considered is the thread count so that it will seal in the 300 bar valves. Even those valves are not that common to see. Most places have pressure regulators to limit the psi on the fill line or the cascade bank is not over 3600 or such to have to consider a problem with the scenereo you suggest of a high pressure whip on a low presrue tank. Lp's are commonly filled to over 3000. Many tanks have higher pressure valves to do cave fills ect. Lastly the 300b whip is only effective if the tank valve is correct and now that opens up the integrity discusions of the right valve for the right tank and the fill station denying a fill by those that barely know what end of the whip to connect. My tanks are lp they have 200b valves i fill them with a whip that has a male on it with threads the leignth that will accompodate a 300b valve. They have no safety gizmos on the end of the whip. I see no problem with whips lke this unless they are being fed from a say 6k cascade, I havent found that system anywhere either. most use cascades of 20+ 3500# tanks for bulk storage. Using one whip type allow fills for all din tanks. I would next guess that if someone was able to fill a 300b (4000+) tank it would have its own special whip for it and most likely have the safety gizmos on the tip of it like your article shows. Unless its a 2250 tank i dont know of any tank thta cant handle 3500 psi, even unintentionly. (2400) lp's burst disk holds to over 3600.

300 bar cylinders are common enough here to mean that mistaking a 232 for a 300 is not unlikely. I suppose that is less of a problem where you are.

 

[SubAquatix]

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.

Tom, I think what KWinter is saying is, just because you might know it to be true, does not mean it is in the best interest of all to share.

First off, while once "extremely common", much of that has changed with the availability of HP tanks. Secondly, while common in some areas, I would doubt extremely common is a correct statement. Most reputable shops will be very cautious about replacing the correct size burst disks because, silly as you might think them to be, they are an actual requirement by DOT. As a shop, the requirement is to put in a burst disk that matches the specification of the tank for a given valve. Any incident that occurs with an improperly installed burst disk would clearly expose that shop to liability.

---------- Post added April 5th, 2015 at 11:21 PM ----------

So, here are some observations, probably different from many of your own.

Faber is actually made here in North Carolina and the tours are always fun. When you go there, it is always fun to note that they do not make either LP or HP cylinders. All they make are steel cylinders, that are then marked and registered with the appropriate authorities based on market need. Yep, Punch out 50 blanks, extrude them, crown and thread them, and then register them, dividing them by market need. Guess what! Many aren't even for Scuba use!! The way they do this is by insuring that the cylinders created meet or exceed the most rigid requirements of a group of cylinders. If that is for HP scuba, the obviously any CO2, scientific or LP scuba cylinders with lesser requirements can easily use them as well. That said, once stamped and registered, it is illegal to overfill that cylinder past its rated pressure, regardless of whether or not people do.

Regarding valve, the story I received from Sherwood some years ago goes like this. While with yoke it never mattered, since they are all rated at or below 232 bar, Europe was creating 300 bar gear and 300 bar regulators. In order to avoid damaging a regulator that was only rated at 200 bar, a deeper DIN was created in which a 200 bar regulator, having fewer threads, would not be able to seat properly. In this manner, one would never over pressurize the first stage and possibly damage it. Over time, nearly all of the regulators manufactured could handle these higher pressures and they were fitted with 300Bar DIN connections. At the same time, and actually quite recently here in the US, the decision has been made, at least for now, not to adopt 300 bar for Scuba diving, so you are seeing fewer and fewer 300 Bar valve options. instead, they bumped the 200 Bar to include 232 bar as a capability, therefore supporting both LP and HP in a single valve set. Because these valves are connecting to DOT registered cylinders, and the US has elected to require burst/rupture disks on hi pressure cylinders, valves made for US consumption are ported for a burst disk.

I forget the manufacturer, but, a few years ago, there was an extremely low profile valve made in Europe that we were all cambering to get our hands on for our rebreather projects. Many of us ordered them, only to get a buy back offer from the US importer. It seems they did not have the requisite burst disk ports and should never have been sold in the US.

Sadly, mine had already been lost and I was unable to return them.

 

[tbone1004]

similar observations Rob, but I thought the DoT rule was the burst discs must not exceed hydro pressure, but it can't be less than like 110% of the rated pressure, or more than 80% of the burst pressure *not sure what these are on the tanks, but it is well over hydro pressure*. So in that case, all of the 2400 bottles would be able to take 4000psi burst discs, and in that case, they are still fully legal according to the DoT, and as long as the valve is rated to pressures higher than the burst disc, then no issues.

 

[SubAquatix]

I never said match the tank pressure, only the specification provided by DOT. ;-) I believe the actual specification merely states "Not to exceed the rated test pressure", but I am sure someone will look up the actual law and provide it here.

Sherwood, for example, provides DoT recommendations for all 3AA, 3A, and 3AL cylinders, 3000 psi with burst disks set at a min of 4500psi, and a max of 5000psi. http://www.sherwoodvalve.com/assets/base/doc/techspec.pdf Obviously each fill, and use will re-stress the disk which is why I change those on my rentals with each valve rebuild.

This is why I think swapping burst disk I much less common than you imply. Frankly, there isn't a logical reason to do it, unless your fills are exceeding 4000psi.