Gas mix

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My AN/DP course (one dive left) has all been air backgas. If you dive the best nitrox mix for a given depth, you won't have a lot of deco to do. Which is normally a good thing, but not so much when you want to get practice with actual deco. Plus air is cheap/free depending on the deal with your shop (I've got a yearly fill card) while O2 has an associated cost.
 
So basically EAN to 5.54 ATA . What about gas density and END for deep dives?

Yes for Deco Procedures but for this range I would normally recommend Helitrox which covers the use of up to 35% Helium for dives to 45m. Using Helium greatly reduces the gas density and END for deep dives.
 
Yes for Deco Procedures but for this range I would normally recommend Helitrox which covers the use of up to 35% Helium for dives to 45m. Using Helium greatly reduces the gas density and END for deep dives.

@Mark Powell

TDI needs to update its website. There’s conflicting info for Helitrox for helium percentage. The brief info about the course mentions mixes with no more than 20% helium. However, the standards actually mention up to 35% helium. Screen shots below. This caught my attention as I’m signed up for AN/DP/Helitrox next year with all bookwork completed.

I’ve had 20% helium maximum on the brain. Did the percentage recently change?

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The numbers in the footer correspond to a MMYY. The newest standards were published within the past month.
@Mark Powell

TDI needs to update its website. There’s conflicting info for Helitrox for helium percentage. The brief info about the course mentions mixes with no more than 20% helium. However, the standards actually mention up to 35% helium. Screen shots below. This caught my attention as I’m signed up for AN/DP/Helitrox next year with all bookwork completed.

I’ve had 20% helium maximum on the brain. Did the percentage recently change?

View attachment 552216 View attachment 552217
 
This standard was just changed for the 2020 standards. The maximum helium percentage is now 35%. The course description just has not been updated on the website yet.

@Mark Powell

TDI needs to update its website. There’s conflicting info for Helitrox for helium percentage. The brief info about the course mentions mixes with no more than 20% helium. However, the standards actually mention up to 35% helium. Screen shots below. This caught my attention as I’m signed up for AN/DP/Helitrox next year with all bookwork completed.

I’ve had 20% helium maximum on the brain. Did the percentage recently change?

View attachment 552216 View attachment 552217
 
This standard was just changed for the 2020 standards. The maximum helium percentage is now 35%. The course description just has not been updated on the website yet.

That explains the discrepancy, then. Thank you!

ETA: I just completed the Trimix book last week and so this is an interesting change. A friend is loaning me a suit bottle and rigging kit. Just need to add a hose and OPV to an extra first stage I have.
 
i did AN/DP and ER as sort of 1 long combined course, the first couple dives we did were skills dives on a local shipwreck theres a good spot with a railing all the way around to use as a reference for buoyancy during skills and its was 55-65' feet and max depth we got to was around 100 on those so we used air or 32% and 50% he didn't care what we used as long as we were within the MOD and we both used the same gas with same plan. the deeper dives we used air and 50%, with the last 5 i think? maybe 6 dives we were using air,50%,and o2



Its a fantastic course have fun!

TDI doesn't use standard gases like GUE does so its dependant on planned depth
 
@Mark Powell

TDI needs to update its website. There’s conflicting info for Helitrox for helium percentage. The brief info about the course mentions mixes with no more than 20% helium. However, the standards actually mention up to 35% helium. Screen shots below. This caught my attention as I’m signed up for AN/DP/Helitrox next year with all bookwork completed.

I’ve had 20% helium maximum on the brain. Did the percentage recently change?

View attachment 552216 View attachment 552217

Thanks for spotting that. As the others have said that only just changed in the standards. I have emailed the website team to remind them that the course description also needs to be updated.
 
https://www.shearwater.com/products/swift/

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