DIR/GUE gear updates?

[PfcAJ]

Dil and wing gas for a square profile 200ft wreck dive is about 7cf for me, can't imagine its much different for the JJ version.
6 or 7cf in my suit in cold water with some mid-water futzing
Perhaps 6 to 8cf of O2 depending on the total runtime (~70 to 100mins)

Interesting. Did a ~210ft relatively square ocean dive with the rb80 a few months ago and used 24cuft of backgas. 50mins till we were at the 70' stop.

 

[ScubaInChicago]

How much backgas are you using per dive (in cuft)? Wing, loop, whatever else that kevorkian machine needs.

What rjack said...The only dil used is on decent to fill wing and loop volume. After that 1L/min of o2 is metabolized out of about 600 free liters (3L x 200 bar). If flushing with dil/o2 or a sawtooth profile, those numbers will go up, but not substantially. As a side note, your po2 does not drop rapidly enough at depth that it shouldn't easily be caught in time with all kinds of flashing red lights. Join the darkside, I'll even let you borrow my rig (WITH BOV) for the course.

 

[rjack321]

Probably 1/2 or more of my dil use is in the wing. It mostly depends on how many bailouts I bring and how much lead I have to add to hold them down if they were to empty. In July is was using ~800 psi of dil out of an AL19 per 165-200ft dive. I guess that's closer to 5cf.

Since the RB80 is keyed to respiration I am guessing gas use goes up in situations where your SAC rate would go up? Like 40f water.

 

[rjack321]

After that 1L/min of o2 is metabolized out of about 600 free liters (3L x 200 bar). .

Really? This seems pretty high. Or are you just averaging across the whole dive and a bunch of this gets dumped on ascent?
I've only done one actual O2 consumption exercise (in class). Steady swimming at about 75% of my max, consumption was 0.75 L/min

Interesting. Did a ~210ft relatively square ocean dive with the rb80 a few months ago and used 24cuft of backgas. 50mins till we were at the 70' stop.

What's the deco gas consumption?

 

[PfcAJ]

Probably 1/2 or more of my dil use is in the wing. It mostly depends on how many bailouts I bring and how much lead I have to add to hold them down if they were to empty. In July is was using ~800 psi of dil out of an AL19 per 165-200ft dive. I guess that's closer to 5cf.

Since the RB80 is keyed to respiration I am guessing gas use goes up in situations where your SAC rate would go up? Like 40f water.

Yea, it would go up a little. If your normal sac rate is .5 and when its cold it becomes a .7, it would go up by an effective rate of .02. Probably undetectable gas consumption wise.

 

[PfcAJ]

What's the deco gas consumption?

The needle doesn't even move on oxygen, maybe a few hundred PSI out of an al40 of 50%. I vent often to keep the fo2 up.

 

[rjack321]

The needle doesn't even move on oxygen, maybe a few hundred PSI out of an al40 of 50%. I vent often to keep the fo2 up.

I can tell when I've hit my maximal offgassing as I have to vent the loop a bit more, the volume of inerts in there tends to creep up. On a 30min 200ft dive this is usually around 40-30ft. If I'm being bounced around by waves, distracted by critters on a wall or slope, scootering, or just having a crappy day and having to concentrate a lot I don't notice. Its only really noticeable if I'm uber solid at the stop for awhile - which doesn't happen much lol.

 

[PfcAJ]

I can tell when I've hit my maximal offgassing as I have to vent the loop a bit more, the volume of inerts in there tends to creep up. On a 30min 200ft dive this is usually around 40-30ft. If I'm being bounced around by waves, distracted by critters on a wall or slope, scootering, or just having a crappy day and having to concentrate a lot I don't notice. Its only really noticeable if I'm uber solid at the stop for awhile - which doesn't happen much lol.

On SCR the venting is to reduce the oxygen drop. 50% turns into like 44% pretty quick, and thats independent of any inerts being exhaled due to decompression.

 

[rjack321]

On SCR the venting is to reduce the oxygen drop. 50% turns into like 44% pretty quick, and thats independent of any inerts being exhaled due to decompression.

Yes I know, I was just comparing loop venting issues

 

[ScubaInChicago]

On SCR the venting is to reduce the oxygen drop. 50% turns into like 44% pretty quick, and thats independent of any inerts being exhaled due to decompression.

The fo2 drop of the RB80 is craziness. I can see why some of the older RB80 divers are starting to use an o2 cell & Petrel to monitor fo2 during dives.