Buoyancy of US 104/120s

*David Martin* · April 20th, 2008, 04:04 PM

Can someone let me know what the buoyancy characteristic of the US 104s and/or 120s are? Either with or without valve/bands (just say which). Or what the mass of the steel and the internal volume is, so that I can work it out.

I've dived 104s a couple of years ago and although I remember they were noticeably heavier than the 12s we use in the UK I don't know by how much. I know I was overweighted with a Pro-14 an alu backplate and no lead; however when I go back I'll have noticeably newer (and hence more buoyant) undersuit and a 9Ah canister. It would be good to know whether I should be taking a steel or an alu plate with me.

David

Ronaldo · April 20th, 2008, 04:36 PM

Maybe this can help you out..

***Bob Cooper*** · April 22nd, 2008, 08:58 PM

David

i would hazard a guess that somebody of your size wering a new 400g undersuit, Pro 14, Ali plate and 104s would not need any more weight, even with empty tanks. They are very heavy in the water.

Bob

*Clare Gledhill* · April 22nd, 2008, 09:53 PM

In 104 if I don't wear a 400 gramme undersuit I can't talk to anyone on the surface....

...which they may consider a bonus

Roel · April 23rd, 2008, 10:38 AM

Quote: (Originally Posted by Clare Gledhill)

In 104 if I don't wear a 400 gramme undersuit I can't talk to anyone on the surface....

...which they may consider a bonus

Maybe some of your students would like to promote 104's in Europe

Ali Fikree · April 23rd, 2008, 11:51 AM

Quote: (Originally Posted by Clare Gledhill)

In 104 if I don't wear a 400 gramme undersuit I can't talk to anyone on the surface....

...which they may consider a bonus

They use 104's in The Shire??

A

limeyx · April 23rd, 2008, 05:48 PM

Quote: (Originally Posted by David Martin)

Can someone let me know what the buoyancy characteristic of the US 104s and/or 120s are? Either with or without valve/bands (just say which). Or what the mass of the steel and the internal volume is, so that I can work it out.

I've dived 104s a couple of years ago and although I remember they were noticeably heavier than the 12s we use in the UK I don't know by how much. I know I was overweighted with a Pro-14 an alu backplate and no lead; however when I go back I'll have noticeably newer (and hence more buoyant) undersuit and a 9Ah canister. It would be good to know whether I should be taking a steel or an alu plate with me.

David

It depends on the manufacturer somewhat.

This list is a good start
TECHDIVINGLIMITED.COM

The PST 104 is -3.3 pounds empty with valve according to that table.
And the PST HP120 is neutral when empty

However, there are different manufacturers of those tanks which can be far more negative empty.

According to this chart ....

XS Scuba Worthington Steel Cylinder Specifications

The HP130's (which I think are approx the size of 104's) are 16L tanks and HP119/120 are basically 15L's

These tanks are heavy full, but their empty buoyancy is such that for me with a 400G and no heavy light, I still need quite a bit of lead to sink them when they are empty.

*David Martin* · April 23rd, 2008, 06:47 PM

Thanks to all who have replied. I gather we'll be using 104s and 95s rather than 104s and 120s, which seem to have significantly closer buoyancy characteristics to one another.

David

April 20th, 2008, 04:04 PM	#1 (permalink)
David Martin(Offline) Instructor candidate Join Date: Jan 2006 Location: London, E11 Posts: 419	Buoyancy of US 104/120s Can someone let me know what the buoyancy characteristic of the US 104s and/or 120s are? Either with or without valve/bands (just say which). Or what the mass of the steel and the internal volume is, so that I can work it out. I've dived 104s a couple of years ago and although I remember they were noticeably heavier than the 12s we use in the UK I don't know by how much. I know I was overweighted with a Pro-14 an alu backplate and no lead; however when I go back I'll have noticeably newer (and hence more buoyant) undersuit and a 9Ah canister. It would be good to know whether I should be taking a steel or an alu plate with me. David

April 22nd, 2008, 09:53 PM	#4 (permalink)
Clare Gledhill(Offline) GUE Instructor Site Admin Pacman Champion! Join Date: Nov 2005 Location: UK Posts: 1,540	In 104 if I don't wear a 400 gramme undersuit I can't talk to anyone on the surface.... ...which they may consider a bonus __________________ Clare . "Keep away from people who try to belittle your ambitions....Small people always do that, but the really great make you feel that you too can become great." Interested in DIR dive training? Always happy to chat/answer questions so get in touch via PM or visit www.dirdiver.co.uk

April 23rd, 2008, 11:51 AM	#6 (permalink)
Ali Fikree(Offline) New Member Join Date: Dec 2005 Location: Dubai Posts: 460	Quote: (Originally Posted by Clare Gledhill) In 104 if I don't wear a 400 gramme undersuit I can't talk to anyone on the surface.... ...which they may consider a bonus They use 104's in The Shire?? A __________________ Four wheels move the body, two wheels move the soul

April 23rd, 2008, 05:48 PM	#7 (permalink)
limeyx(Offline) New Member Join Date: Nov 2005 Location: Los Angeles, CA Posts: 708	Quote: (Originally Posted by David Martin) Can someone let me know what the buoyancy characteristic of the US 104s and/or 120s are? Either with or without valve/bands (just say which). Or what the mass of the steel and the internal volume is, so that I can work it out. I've dived 104s a couple of years ago and although I remember they were noticeably heavier than the 12s we use in the UK I don't know by how much. I know I was overweighted with a Pro-14 an alu backplate and no lead; however when I go back I'll have noticeably newer (and hence more buoyant) undersuit and a 9Ah canister. It would be good to know whether I should be taking a steel or an alu plate with me. David It depends on the manufacturer somewhat. This list is a good start TECHDIVINGLIMITED.COM The PST 104 is -3.3 pounds empty with valve according to that table. And the PST HP120 is neutral when empty However, there are different manufacturers of those tanks which can be far more negative empty. According to this chart .... XS Scuba Worthington Steel Cylinder Specifications The HP130's (which I think are approx the size of 104's) are 16L tanks and HP119/120 are basically 15L's These tanks are heavy full, but their empty buoyancy is such that for me with a 400G and no heavy light, I still need quite a bit of lead to sink them when they are empty. __________________ my divelog: http://www.mydivinglife.com/limeyx

April 22nd, 2008, 08:58 PM	#3 (permalink)
*Bob Cooper*(Offline) Moderator - "Don't stop me now!" Join Date: Nov 2005 Location: South East London, UK Posts: 680	David i would hazard a guess that somebody of your size wering a new 400g undersuit, Pro 14, Ali plate and 104s would not need any more weight, even with empty tanks. They are very heavy in the water. Bob

April 23rd, 2008, 10:38 AM	#5 (permalink)
Roel(Offline) New Member Join Date: Dec 2005 Location: Netherlands Posts: 374	Quote: (Originally Posted by Clare Gledhill) In 104 if I don't wear a 400 gramme undersuit I can't talk to anyone on the surface.... ...which they may consider a bonus Maybe some of your students would like to promote 104's in Europe

April 23rd, 2008, 06:47 PM	#8 (permalink)
David Martin(Offline) Instructor candidate Join Date: Jan 2006 Location: London, E11 Posts: 419	Thanks to all who have replied. I gather we'll be using 104s and 95s rather than 104s and 120s, which seem to have significantly closer buoyancy characteristics to one another. David