Stage/deco bottles for Tech 2...

Vie · June 14th, 2007, 12:22 PM

Apologies if this has been asked before - I'm not even sure I'm posting this question in the right section but here goes...

For the Tech 2 class, am I correct in understanding that, in addition to backgas, each diver will be carrying an AL80 stage bottle, an AL40 deco bottle (EAN 50) and another bottle with O2?

GUE specifies...

"Tanks/Cylinders: Students are required to use dual tanks/cylinders connected with a dual outlet isolator manifold, which allows for the use of two first-stages. All dives must start with a minimum of 80 cubic feet/2250 liters of gas. Also required are two decompression cylinders: one (1) greater than 30 cubic feet/850 liters for Nitrox and one (1) 30 cubic feet/850 liters, or greater, for an additional deco gas."

But this does not seem to match the number of bottles alluded to in the Tech 2 class report that I've read.

I've seen both AL40 and AL30 used for O2 - is there any particular reason why one size would be preferable over the other?

*JohnKendall* · June 14th, 2007, 12:41 PM

The best thing to do is talk with your instructor. On our Tech2 course we used 1 AL80 for bottom gas, then a mixture of AL80s, AL7's and AL40s for the 50% or O2.
We then had a 2nd set of all the bottles to allow us to take it all out on the boat at the beginning of the day and have gas for 2 dives.

A lot of it comes down to the logistics of the course and what is available locally.

HTH

John

graham_hk · June 14th, 2007, 01:12 PM

Vie,

When I did Tech 2 we did it with Al80 stages and Al40 deco bottles. I would think the Al30 part in the standards is just referring to the minimum. I think 30s would be excellent for oxygen if you have a booster but not so good at only ~100bar. They would be too small for all but the weeniest of dives for the 50%.

Graham

Mal Bridgeman · June 14th, 2007, 01:42 PM

A small diversion.....

Am I right in thinking an AL30 is the same diameter as an AL40 but shorter in the same way an AL60 is a shorter version of an AL80?

Do they sling nicely?

TIA
Mal

graham_hk · June 14th, 2007, 02:01 PM

Quote: (Originally Posted by Mal Bridgeman)

A small diversion.....

Am I right in thinking an AL30 is the same diameter as an AL40 but shorter in the same way an AL60 is a shorter version of an AL80?

Do they sling nicely?

TIA
Mal

Narrower and shorter - almost unnoticable in the water

Mal Bridgeman · June 14th, 2007, 02:13 PM

Quote: (Originally Posted by graham_hk)

Narrower and shorter - almost unnoticable in the water

Thanks
Mal

P.S. Happy Birthday fella!

graham_hk · June 14th, 2007, 03:03 PM

Quote: (Originally Posted by Mal Bridgeman)

P.S. Happy Birthday fella!

Thanks - but not sure how you found out since I am pretty sure I lied and listed my birthday as 1/4/1901 on here

Tricky · June 14th, 2007, 07:43 PM

Quote: (Originally Posted by graham_hk)

Thanks - but not sure how you found out since I am pretty sure I lied and listed my birthday as 1/4/1901 on here

I saw it on YD

Happy Birthday

maccajim · June 16th, 2007, 07:56 AM

tanks depend on the country what is available and water temp.
here in aus the standard is becoming 2 luxfer 80's and 1 luxfer 40 for 02. the 80's are a bottom stage and deco %50 the 40 for 02.

We used to use 40's here for %50 but it becomes more practical to use 80's as u can do 2 tech1 dives with the one fill and luxfer 40's were hard to get here until recently.

i know the brits almost always use 80's for %50 as they dive colder water and big current wich can increase your sac a lot.

in your warmer water and with what is available it is up to u if u want 2 lux 80's or 1*80 and 2* 40's ask some local tech2 guys or Gideon (GUE instructor in singapore) as he dives the same temp water as u. I think the 80's are much more practical for multi day diving and a weekend away where it is hard to get fills.
good luck

June 14th, 2007, 12:22 PM	#1 (permalink)
Vie(Offline) Loner at the ball... Join Date: Nov 2005 Location: Krung Thep, Siam, mostly Posts: 189	Stage/deco bottles for Tech 2... Apologies if this has been asked before - I'm not even sure I'm posting this question in the right section but here goes... For the Tech 2 class, am I correct in understanding that, in addition to backgas, each diver will be carrying an AL80 stage bottle, an AL40 deco bottle (EAN 50) and another bottle with O2? GUE specifies... "Tanks/Cylinders: Students are required to use dual tanks/cylinders connected with a dual outlet isolator manifold, which allows for the use of two first-stages. All dives must start with a minimum of 80 cubic feet/2250 liters of gas. Also required are two decompression cylinders: one (1) greater than 30 cubic feet/850 liters for Nitrox and one (1) 30 cubic feet/850 liters, or greater, for an additional deco gas." But this does not seem to match the number of bottles alluded to in the Tech 2 class report that I've read. I've seen both AL40 and AL30 used for O2 - is there any particular reason why one size would be preferable over the other? Last edited by Vie; June 14th, 2007 at 12:26 PM.

June 14th, 2007, 12:41 PM	#2 (permalink)
JohnKendall(Offline) GUE Instructor/DIRX Moderator Join Date: Nov 2005 Location: Cambridge, UK Posts: 1,097	The best thing to do is talk with your instructor. On our Tech2 course we used 1 AL80 for bottom gas, then a mixture of AL80s, AL7's and AL40s for the 50% or O2. We then had a 2nd set of all the bottles to allow us to take it all out on the boat at the beginning of the day and have gas for 2 dives. A lot of it comes down to the logistics of the course and what is available locally. HTH John __________________ John Kendall http://www.guetraining.com/ GUE Instruction, Santi and Halcyon Equipment NEW - Online Santi Shop

June 14th, 2007, 01:12 PM	#3 (permalink)
graham_hk(Offline) Pinoy ako pinoy Join Date: Nov 2005 Location: here, there and everywhere Posts: 779	Vie, When I did Tech 2 we did it with Al80 stages and Al40 deco bottles. I would think the Al30 part in the standards is just referring to the minimum. I think 30s would be excellent for oxygen if you have a booster but not so good at only ~100bar. They would be too small for all but the weeniest of dives for the 50%. Graham __________________ DIN caps and plugs with free world wide postage: www.dustcap.halcyon-hk.com

June 14th, 2007, 01:42 PM	#4 (permalink)
Mal Bridgeman(Offline) New Member Join Date: Nov 2005 Location: Suffolk, UK Posts: 662	A small diversion..... Am I right in thinking an AL30 is the same diameter as an AL40 but shorter in the same way an AL60 is a shorter version of an AL80? Do they sling nicely? TIA Mal __________________ Opinions and beliefs are correct at the time of posting but are subject to change without any notice or obligation on the part of the author.

June 14th, 2007, 02:01 PM	#5 (permalink)
graham_hk(Offline) Pinoy ako pinoy Join Date: Nov 2005 Location: here, there and everywhere Posts: 779	Quote: (Originally Posted by Mal Bridgeman) A small diversion..... Am I right in thinking an AL30 is the same diameter as an AL40 but shorter in the same way an AL60 is a shorter version of an AL80? Do they sling nicely? TIA Mal Narrower and shorter - almost unnoticable in the water __________________ DIN caps and plugs with free world wide postage: www.dustcap.halcyon-hk.com

June 14th, 2007, 02:13 PM	#6 (permalink)
Mal Bridgeman(Offline) New Member Join Date: Nov 2005 Location: Suffolk, UK Posts: 662	Quote: (Originally Posted by graham_hk) Narrower and shorter - almost unnoticable in the water Thanks Mal P.S. Happy Birthday fella! __________________ Opinions and beliefs are correct at the time of posting but are subject to change without any notice or obligation on the part of the author.

June 14th, 2007, 03:03 PM	#7 (permalink)
graham_hk(Offline) Pinoy ako pinoy Join Date: Nov 2005 Location: here, there and everywhere Posts: 779	Quote: (Originally Posted by Mal Bridgeman) P.S. Happy Birthday fella! Thanks - but not sure how you found out since I am pretty sure I lied and listed my birthday as 1/4/1901 on here __________________ DIN caps and plugs with free world wide postage: www.dustcap.halcyon-hk.com

June 14th, 2007, 07:43 PM	#8 (permalink)
Tricky(Offline) New Member Join Date: Nov 2005 Location: Reading, Berkshire Posts: 555	Quote: (Originally Posted by graham_hk) Thanks - but not sure how you found out since I am pretty sure I lied and listed my birthday as 1/4/1901 on here I saw it on YD Happy Birthday __________________ "I know that you believe that you understand what you think I said, but I am not sure you realise that what you heard is not what I meant." "Make me one with everything" said the Mystic to the Hamburger vendor. UK Diving Forum Sryth: A Free Online Text RPG Join the Adventure! Fallen Sword: Free online RPG

June 16th, 2007, 07:56 AM	#9 (permalink)
maccajim(Offline) New Member Join Date: Nov 2005 Location: Sydney Posts: 97	hiya vie tanks depend on the country what is available and water temp. here in aus the standard is becoming 2 luxfer 80's and 1 luxfer 40 for 02. the 80's are a bottom stage and deco %50 the 40 for 02. We used to use 40's here for %50 but it becomes more practical to use 80's as u can do 2 tech1 dives with the one fill and luxfer 40's were hard to get here until recently. i know the brits almost always use 80's for %50 as they dive colder water and big current wich can increase your sac a lot. in your warmer water and with what is available it is up to u if u want 2 lux 80's or 180 and 2 40's ask some local tech2 guys or Gideon (GUE instructor in singapore) as he dives the same temp water as u. I think the 80's are much more practical for multi day diving and a weekend away where it is hard to get fills. good luck