Is enviro seal really halping in some cases?

[elan]

Actually if you examine adiabatic cooling you will note that it is proportional to the pressure drop; so raising the IP actually means just a little LESS cooling.

Nope more, as I was referring to the second stage.

For the first stage 25psi would only represent 1% if we talk about an LP tank at full pressure. And the further we suck the tank down the less cooling will occur, yet for the second stage it will constantly be at 16% more at depth and this is where the water would be likely the coolest.

 

[Capt.Gene]

The overbalance feature is a coincidental effect .
Pull the plunger, fill the spring chamber with Vodka and screw the enviro cap back in place.
No risk of freeeze and no more overbalance feature.
Pure speculation as I haven't had need to try this and we are always short of potato juice.

 

[elan]

The overbalance feature is a coincidental effect .
Pull the plunger, fill the spring chamber with Vodka and screw the enviro cap back in place.
No risk of freeeze and no more overbalance feature.
Pure speculation as I haven't had need to try this and we are always short of potato juice.

I think that aint ever gonna happen as vodka will never reach the chamber And the overbalanced effect might as well get transformed into outofbalanced . So meanwhile I think will have to dive overbalanced.

 

[Thalassamania]

We always used 151 rum and each vernal equinox drank a toast to the returning sun.

 

[elan]

We always used 151 rum and each vernal equinox drank a toast to the returning sun.

My aging liver will revolt

 

[Thalassamania]

If you take good care of your liver, it will take good care of you.

 

[keyshunter]

We always used 151 rum and each vernal equinox drank a toast to the returning sun.

Now that's MY favorite kind of overbalancing.

elan,
If you research the topic, you will find that overblancing is just a happy accident which occurs as a function of adding the second (environmental) seal. Naturally, the term was jumped upon by the marketing types as a real selling point. In actuality, at recreational depths, overbalancing has no real significance. While it may have some significance when doing deep air, a slight decrease in reg performance was the least of our worries. Today, with mix being readily available, not many divers do deep air.

 

[halocline]

Actually if you examine adiabatic cooling you will note that it is proportional to the pressure drop; so raising the IP actually means just a little LESS cooling.

True for the first stage, but not for the 2nd. Higher IP means more of a drop in the 2nd stage. And since the pressure drop from supply to IP is so much greater than from IP to ambient, a 20 PSI or so increase in IP will have a proportionally much larger effect on the 2nd stage. But the idea behind lowering IP for cold water use is primarily to slow flow to the 2nd stage, not really to have any significant effect on adiabatic cooling. With high performance balanced 2nds that compensate for changes in IP, I kind of doubt lowering the IP for cold water use has much of an effect.

 

[markr]

True for the first stage, but not for the 2nd. Higher IP means more of a drop in the 2nd stage. And since the pressure drop from supply to IP is so much greater than from IP to ambient, a 20 PSI or so increase in IP will have a proportionally much larger effect on the 2nd stage. But the idea behind lowering IP for cold water use is primarily to slow flow to the 2nd stage, not really to have any significant effect on adiabatic cooling. With high performance balanced 2nds that compensate for changes in IP, I kind of doubt lowering the IP for cold water use has much of an effect.

Are you sure this is correct? Based on Elan's previous statement he sees a 25 psi increase in IP going from the surface to 160'. The ambient pressure on the second stage for that change in depth should be something like 4.8 times the surface pressure. So the IP will increase from say 140 psi to 165 psi while the ambient pressure on the second stage increases from 14 psi to 67 psi. The pressure drop across the second stage goes from 126 at the surface to 98 at 160'.

 

[halocline]

Are you sure this is correct? Based on Elan's previous statement he sees a 25 psi increase in IP going from the surface to 160'. The ambient pressure on the second stage for that change in depth should be something like 4.8 times the surface pressure. So the IP will increase from say 140 psi to 165 psi while the ambient pressure on the second stage increases from 14 psi to 67 psi. The pressure drop across the second stage goes from 126 at the surface to 98 at 160'.

We're talking about different things, I think, I was addressing changes in IP vs the drop from supply (potentially 3000+PSI) to IP vs IP to ambient, which would consistently be about 125-140 PSI. (IP is usually thought of in PSIG, not absolute)

You might be overlooking something with your numbers for IP change at depth; IP always depth compensates along with ambient. So at 160 ft (lets say 5 atm for simplicity) IP for a regulator set at 135 PSI would be 135 plus somewhere around 73 PSI, or around 208. That keeps it constant above ambient, otherwise it wouldn't work. "Overbalanced" regs increase the IP even more, elan's example was that he thought it might increase as much as 25PSI in addition to the change in ambient, if I remember his post.