DIR- Generic Analyze gas - right or left post?

[steinbil]

I just heard on the UTD podcast (episode #29 around 57:20) that they advocate filling on right post and analyzing on left post. In my GUE fundies we filled and analyzed on the right post, and I believe that’s also in the GUE SOP.

The argument for analyzing on the left was catching filling mistakes (closed isolator etc.), but the way I see it, if the isolator is closed by mistake when filling, who cares what’s in the left tank, you’re going to be breathing off the right post! In any case you’re aborting the dive, or sharing gas while aborting if you open it under water. And of course you should check that the isolator is open both when analyzing and during the flow check before you start the dive.

So in case I somehow miss the closed isolator twice and start the dive, I would rather know what I’m breathing off the right post than having analyzed the left…

Am I missing anything here? Any UTD divers want to chime in and explain this to me?

 

[tbone1004]

Disclaimer, neither GUE nor UTD diver.

Pros and cons to both sides.
If you fill/analyze on the right post with your gear assembled, then you should catch a closed isolator from the SPG not having moved. Advantage here is you don't have to remove the left post regulator to analyze if you leave the rig assembled.
If the rig is disassembled, then what I've done is get in the habit of manipulating the isolator before filling and before assembling. If it was closed, you will catch it during analysis as you will hear the pressure moving from one side to the other and then you have to check both posts and the pressure anyway.

I sit firmly in the camp of do what is convenient. The analyzer I use the most has a BC Inflator nipple on it which means that if the rig is assembled then analyzing from the right post is a PITA, and most of the time when I'm analyzing the bottles were filled with the rig assembled so they get analyzed from the left post drysuit inflator/instructor torture device hose. If I'm sharing an analyzer with friends, then whomever gets theirs out first is the one we use and if it's a valve analysis then I analyze it from the right post because the regulator is already off.

I do acknowledge that filling with the rig assembled is somewhat unique to where I live and dive and that most people have their gear fully broken down for filling/analysis and if they are fully broken down then the logic of fill right, analyze left is there but only if you are also doing a pressure check to make sure that it actually filled.

TLDR, manipulate your isolator before you analyze and you'll know if it was closed or not. If it wasn't closed then the post you analyze isn't something that I'm going to get my panties in a wad over, if it is closed then you have to check both posts and the pressure to figure out how to fix it so it still doesn't matter.

 

[rob.mwpropane]

I do the same as @tbone1004

The only thing I have to add is if you're PP blending you'll want to add O2 and fill through the same post. Found out the hard way that adding O2 through one, filling through the other gives wildly different readings (at each post)... no fun when you have a dive scheduled the next morning.

Laid them on their side and all was good 12 hrs later, but now I do any filling through right to keep things idiot proof.

 

[Jack Hammer]

I dont recall in any of my GUE courses being taught to analyze off a particular post. I do recall always verifying the isolator is open. Generally the right post was used due to having the left reg still attatched and also verifying pressure and isolator. On an assembled rig we analyzed via the inflator hose (we had the attachment) as it was simpler than removing a reg

 

[flymolo]

I heard something like you fill on the right and analyze on the right, so you’ll at least know what gas you’re breathing in the extreme case you jump in the water after failing to open the isolator during filling, analyzing, or your pre-dive checks (which if you miss all those opportunities to check your isolator you probably want to re-assess your procedures anyway).

 

[kierentec]

Fill, analyze and label right post, check pressure on left post (and ALWAYS check the isolator).

 

[steinbil]

I heard something like you fill on the right and analyze on the right, so you’ll at least know what gas you’re breathing in the extreme case you jump in the water after failing to open the isolator during filling, analyzing, or your pre-dive checks (which if you miss all those opportunities to check your isolator you probably want to re-assess your procedures anyway).

That‘s what I was thinking too.

Although I see the point of others here that it might not be a big deal since you have multiple other checks to avoid the mistake of jumping in the water with the isolator closed, it seemed strange to me that UTD should be so adamant about always analyzing on the left post.

I would think that in case of a major slip-up, I would feel more comfortable knowing what was in the right tank than the left.

 

[tbone1004]

Fill, analyze and label right post, check pressure on left post (and ALWAYS check the isolator).

Hard and fast no exceptions? Thinking the example of analyzer has a BC inflator on it to check from left post inflator hose?

 

[rjack321]

Hard and fast no exceptions? Thinking the example of analyzer has a BC inflator on it to check from left post inflator hose?

If in doubt close the isolator temporarily and then analyze both posts. It is not that hard to end up with both sides at the same pressure but with wildly different gases when partial pressure blending.

 

[kensuf]

Hard and fast no exceptions? Thinking the example of analyzer has a BC inflator on it to check from left post inflator hose?

Your right post should have your wing inflator. That way you can dump with your left hand while shutting down the post with the right in the event of a stuck inflator. A stuck inflator drill is a skill requirement for AN/DP.