RMV vs SAC rate

[BlueTrin]

It looks like the Perdix does not allow you to enter the tank size to convert the SAC into RMV.

Can I check with you guys that my understanding is correct ?

The SAC is in pressure unit (that would be bar for me), while the RMV is in volume.

Both are adjusted for ambient pressure.

So if I use a 2x12liters twinset and have a SAC of 1bar/min, this would translate to 24liters/min, is that correct ?

 

[foob]

So if I use a 2x12liters twinset and have a SAC of 1bar/min, this would translate to 24liters/min, is that correct ?

Believe so

 

[tursiops]

It looks like the Perdix does not allow you to enter the tank size to convert the SAC into RMV.

Can I check with you guys that my understanding is correct ?

The SAC is in pressure unit (that would be bar for me), while the RMV is in volume.

Both are adjusted for ambient pressure.

So if I use a 2x12liters twinset and have a SAC of 1bar/min, this would translate to 24liters/min, is that correct ?

Yes, remembering it is a surface value. At 10m you'll use twice that. Correct, no way to enter tank size in the computer or the app.

 

[Manatee Diver]

Third party apps like Macdive allow you to enter tank size to get the RMV rate.

 

[Pavao]

SAC vs RMV, who cares what’s called? I think people love to complicate things and this just creates confusion.

I consume x cf3/min at the surface, it’s what matters, from here I can calculate the consumption at any depth, irregardless what name one may assine to it.

One for pressure and the other for volume just leaves room for error in my opinion.

 

[tursiops]

SAC vs RMV, who cares what’s called? I think people love to complicate things and this just creates confusion.

I consume x cf3/min at the surface, it’s what matters, from here I can calculate the consumption at any depth, irregardless what name one may assine to it.

One for pressure and the other for volume just leaves room for error in my opinion.

You may be missing the point of the thread. The OP's computer only reports psi or bars per minute. He wants to convert this to cuft or liters per minute, possibly so you will be happy.

 

[Norwegian Cave Diver]

I use the Shearwater Petral 2 (non AI). In the "Dive Setup - Dive Planner" menus - it requires an RMV value to be entered.
In the Shearwater Cloud version - I can go in after a dive and enter tank info to create a SAC Rate for that specific dive.
Seems like Shearwater should automatically create a RMV for me for each specific dive also. Would be much nicer to enter a very accurate number in the "planning" stage of a dive.

 

[rsingler]

See the Shearwater FAQ for their philosophy on why they do not do that...

Or if it's not there, look thru other threads in this forum. They have responded to this question on more than one occasion.

 

[foob]

I prefer bar/min to liters/min. That's what the gauge goes by.

Easy to convert to liters just multiply tank volume.

 

[BlueTrin]

I prefer bar/min to liters/min. That's what the gauge goes by.

Easy to convert to liters just multiply tank volume.

I prefer l/min because it does not change when I use:

• a 12l
• a 15l
• a twin 12l

The bar/min is not adjusted for ambient pressure so I would prefer to use GTR to estimate how much time remaining is in my tanks. This is probably not true if you have to change depth often during the dive.