[NamTinker]

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Hi guys
Totally new on the list.  If the question has been asked before, I'd accept a routing to the answers, but here goes:
Over here in Southern Africa/Namibia and in the States the general answer when 300bar is mentioned is: "Unreliable, causes rapid wear on equipment, stay away".  From what I can surmise, you UK based divers and also quite a few German divers have had no problems.  Since most, if not all regs (at least the ones I saw) are rated for 300bar, why should using 300bar cylinders accelerate wear?  Any substance to the statement?  (Ignore the issues of gas mixing and whether the station can fill the cylinders for the moment.)
Up to now I have only used rented cylinders from 200-300bar but I am seriously looking at buying my own set.  (Am using Apeks TX50 DIN regs)
Any advice will be appreciated.
Thanks
Coenraad

 

[Dominic]

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Well, if you're filling 232 bar cylinders to 300 bar I could understand it causing rapid wear.. but a 300 bar cylinder filled to 300 bar? Can't see why there'd be a problem.

I suspect they just don't want to admit they can't pump to that kind of pressure

As for 200 vs 232 - I believe 232 was chosen because this is where the real and ideal gas laws meet, and you genuinely get 232 times the volume in the cylinder at this pressure. No other pressure can do this, hence the reason 300 bar leads to more filling problems than 232.

That's just for air tho, of course, so it is'nt the right pressure for Trimix, or even Nitrox presumably..

 

[BSH]

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<font color='#0000FF'>Hi there, There is probably someone else who will give you some more information but here goes with my twopence worth.  As far as I am aware there is no additional wear with 300bar cylinders, we have lots of members at my club who use them purely for the extra gas they give you as quite a few people are now opting for twin 7's which is a nice balanced set up.  I have two sets of 232's but one is a European set which are heavier than the UK ones, the heavier set is the same weight as the 300bar ones so for me it's all down to weight.  All 300bar cylinders are DIN fitting for safety, I use Posiedon regs which are rated to 300bar I think most regs suitable for cold water are.

This is based on my own experience and I am sure someone else will give you some more information.

Fiona

 

[Digger]

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<font color='#000080'>I use 300 bar 7s, and have had no problems so far. I'm sure my gauge doesn't like it, because it only goes to 250, but the needle just keeps going to where the 300 should be!!!

OK, I'm getting a new gauge this week. I know I've been a naughty boy.

As for increased wear on regs etc. the only thing that will wear is possibly the 1st stage and gauge/hose with the full 300 down them. I don't believe it, to be honest. They're designed to do that job, and they will work above 300 I'm sure.

It's probably that their compressors don't have the 300 whip or can't blow to that pressure (more likely) but it's worth thinking about using 300bar fittings for your 232s even, as the DIN will screw right in. Much more secure.

Also, see how much weight you use. I'd imagine down your way you're not using drysuits, so if you get 300 bar tanks, you're going to be on very little weight at all. If you used a full-length 3mm for example, you're going to find yourself overweight with a 300bar twinset and plate most likely. The benefit would be limited in this case.

 

[NamTinker]

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Thanks all.  Thought so.  I'll order my cylinders in 300bar.  
Digger - yes, with a 4mm full suit and a normal single 10l cylinder I am about neutral in fresh water (BC, no backplate).  With twins I drop like a stone (tested in a pool first!).
Our sea temp vary from 4-16C depending on the current.  But I got cold quickly, even in a 7mm suit, so I ordered a drysuit a couple of weeks back.  Should also sort out the weight of the twins.  The commercial diamond divers here use drysuits, the rec divers mostly wet or semi-dry.

 

[Digger]

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<font color='#000080'>Looks like you've got it sorted. If you're in a drysuit, you'll find the 300 bar tanks nice and heavy so you can take some weight off your belt.

Mind you, I don't know if I'd be in a drysuit in 16deg. Unless I was there for a whole long time. Probably longer than the twins would last!!! Each to his own, I suppose.

 

[BSH]

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<font color='#0000FF'>Cricky, Digger you wouldn't get me in anything else but a dry suit not unless the water was at least 25 degrees and overseas.

 

[John Gulliver]

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Quote[/b] (Digger @ May 13 2003,18:07)]As for increased wear on regs etc. the only thing that will wear is possibly the 1st stage and gauge/hose with the full 300 down them. I don't believe it, to be honest. They're designed to do that job, and they will work above 300 I'm sure.

Precisely! The "standard" cylinder here in Sweden is 10 L x 300 bar (although techies tend increasingly to use 200 bar) and our regs/hoses/gauges don't wear out any faster than yours do. The main reason why I personally use a 10 L x 300 bar cylinder is that I'd need 3 kilos more lead if I swithched to 15 L x 200 bar. 232 bar cylinders are still rare here, by the way, although they are beginning to make their mark now that they're EU approved.

 

[kinetic]

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NamTinker...you raised the question I had and was just about to post so having read the replies I have a few questions...if no-one minds....

Firstly I've been weighing twinsets 10 or 12 with 7 or 10 ali side mounts (all at 232). BUT...I had been considering my twins at 300 bar..especially given the weight which is the bonus...unless your lugging them about up a bloody mountain.

I'm really looking at various dive scenarios,

1. local diving in lakes and pits to max 30 meters upto 70 mins in warm water.

2. Deeper diving with deco of upto 45 mins.

3. cavern diving with dives of no more than 3 hours and depth upto 30 but for short period...no deco stops but extra time needed...so I'd need air for 4.5 hours.

I would like to know set ups for anyone who does 1 to 3 or all...

By the way..my cavern diving has not yet reached the point described above but that's as far as i want to go...for now.

I have DIN..so no probs there and my kit is all set for 300...my local shop only does 232 but if I'm elsewhere (where I need it 300 is no problem)

Pointers and hints welcome...

Kinetic / graham

 

[Digger]

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<font color='#000080'>I do parts 1 and 2, if that helps. I've found the twin 300 7s very good for pits to 30m for ages, and they can do the job for deeper dices with deco, but I've usually got my sidemounts along for the ride in that case as backup and extra gas for buddies (if they're anywhere to be seen!)

I do use twin 12s on serious deepies, but it all depends on the dive. They are 232s, but are effective. They do take up a lot of space on the rib, tho.

Can't comment greatly on number 3. Some time soon, maybe, but really most of my pottering is in and out of wrecks, not very serious penetration, but again the 7s are more compact for getting into a tight spot.

Hope this helps.

Digs.

 

[Lawrence Debono]

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Quote[/b] (Digger @ May 14 2003,20:02)]I do parts 1 and 2, if that helps. I've found the twin 300 7s very good for pits to 30m for ages, and they can do the job for deeper dices with deco, but I've usually got my sidemounts along for the ride in that case as backup and extra gas for buddies (if they're anywhere to be seen!)

I do use twin 12s on serious deepies, but it all depends on the dive. They are 232s, but are effective. They do take up a lot of space on the rib, tho.

Can't comment greatly on number 3. Some time soon, maybe, but really most of my pottering is in and out of wrecks, not very serious penetration, but again the 7s are more compact for getting into a tight spot.

Hope this helps.

Digs.

I wish I could get 300 bar tanks here in Canada. I don't have a clue; why they are so regimental on keeping pressures low, on this continent??? It's pathetic to how people come up with stories =

> Ware and tear of hoses, gauges and valves.
> Dangerous for cold diving - high pressure is colder when it is released.
> No compressors available.
> Burst disc for those pressures are not available (I don't like them one bit).
>bla bla bla......

I think that if one can carry more fuel in a compact container (tank) it could be beneficial. Yes it is heavier a bit but more manageable.

Lawrence

 

[NamTinker]

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Initially I also though there was something "bad" about the 300bar.  But, at that time I was only browsing through the local and American continent lists.  You guys have basically confirmed what I "discovered" on researching a bit deeper.  With gas blending, just fill the 300 bar to 200 or 230 bar.  Since 10l is 10l, I would still have the same amount of air than a normal 200bar setup but with the advantage of the extra cylinder weight (off my belt) and the flexibility to go to 300 if I so decide.  Win-Win if you ask me.  Since no manufacturer is going to run the risk of stating equipment is 300bar rated and it's not, I think from an engineering point it would be safe to assume there would be a substantial safety margin as well.
Digger: Wearing a 4mm wetsuit with hoodie I start shivering in 26C water after 45min...

 

[Dominic]

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> Ware and tear of hoses, gauges and valves.

Nonsense, so long as they're 300-bar rated

> Dangerous for cold diving - high pressure is colder when it is released.

Decent coldwater regs make this a non-issue.
I'm not convinced by the physics either - the temp. drop depends on how much gas expands, and that'll be the same regardless of the cylinder pressure, surely? It's your breathing rate that matters.

> No compressors available.

You could get your own compressor. Or a booster pump...

> Burst disc for those pressures are not available (I don't like them one bit).

Simple answer to that one - don't use the stupid things.

>bla bla bla......

Exactly

 

[John Gulliver]

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I would just add that 300 bar cylinders are tested to 450 bar (at least here in Sweden).

 

[Digger]

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<font color='#000080'>Is it me, or are you lot a big load of pansies? 26deg? I'd be in the buff! You'd probably find me in a 3mm shortie by then. Christ. I dream about temperatures over 15!!!

Mind you, Stoney hit 11deg this week! Woo-hoo!!! I almost took my gloves off. It was like a sauna.

I can't believe you guys are getting cold in 26degrees. I really can't. I suppose everyone's different, but I can't be that different to you lot, can I? I'm a big girl like the rest of them when there's snow at the edge of the water. I'll only do half an hour in that, otherwise my hands get useless.

As for my opinions on burst discs... Don't get me started.

 

[NamTinker]

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Yeah Digger, but remember- that's about you guys' normal daytime temp!

 In our world that is classified as mid winter.  Summer temps vary from 32 to 40C.  Even our nights are warmer than average UK days!  So 26 is actually quite COOL weather.

 

[kinetic]

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Nam...I think your topic's been one of the best for a while..

Normal dive temp in Lux, at the moment is still around 5-6 centigrade...that's the lake by the way not the coastline...I'll let you lot find the Luxembourg coastline on the map..if you find it PLEASE TELL ME.

Digger's right..you're bloody lucky at 26 centigrade..I had a barbie in shorts in the garden when it was 17 cent last week...I had my sunscreen on and the works.

Thanks all for comments...

so..is it twin 10s at 300bar with 7l alis side mounts?

and alis only go to 232b..so there's no discussion there...right?

Cheers for now

Graham

 

[Steve L.]

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I think one reason why the areas you mentioned are so against 300 bar is as follows;

1. Aluminium 200bar cylinders are so numerous, it would not be economical for dive centres to upgrade to steel 300`s

2. 300 bar tanks hold a lot of air, thus allowing you to stay under a lot longer. Certainly in the States (Florida), where they usually run a morning and afternoon dive trip, it dos`nt make sense to encourage divers to stay underwater for too long if, as a dive boat operator, you want to get back to pick up the next lot of cattle.

3. Staying underwater longer can lead to potential things such as DCI etc. If a dive operator can limit your time underwater by only giving you a certain amount of air, then that makes life easier for them.

Despite the emergance of DIN fittings and 300 bar cylinders, which, to be honest make A clamps and 200/232 bar cylinders obselete, there is very little chance of this standard of equipment catching on in most tourist/warm water locations.

 

[kinetic]

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ok...good

so why ever bother with A s?

My buddy was so scared lastweekend when he saw a DIN....it was his first one..and I had to calm him down and take my own gear apart as an exampmple to show him...

din SHOULD BE STANDARD

g

 

[NamTinker]

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kinetic: I agree - DIN should be standard.  Can you think of a disadvantage using DIN?  I can't.  But that said - I have the Apeks adapter just in case the dive operator do not have a DIN cylinder.
Steve L: We have some reefs on the African West Coast where we did three dives a day BUT everybody sticks to the rules, the water is warm so nobody gets DCS from being under too long.  Not deep 14-20m.  Luckily we have not yet entered the liability crazy zone like in other parts of the world!  So operators should not be allowed to use equipment to govern diving times - that is solely the diver's responsibility.
Oddly enough - most operators around here use steel 200-230 bar cylinders.
It is also becoming more popular to use Nitrox for the long, shallow reef dives - less tiring and N uptake.
Digger: With the exchange rate of about 1 UK pound=12-13 South African rand/Namibian dollar, a holiday over here should be cheap!  Just remember the sunscreen...