Tank Moist Air Intrusion during venting

[nimoh]

It all depends upon your situation.

Here in Colorado, there is so little demand for nitrox that most shops won't even make it. For most shops, even 98% of their air fills are for OW classes--there is very little local diving. For those that do, banking nitrox would be a ridiculously uneconomical waste of space. I don't know every shop in the state's situation, but every one I know that provides nitrox does it by partial pressure blending in the tank.

For those who say the blender is lazy for doing this, you cannot be more wrong. Partial pressure blending in the tank without a booster is extremely labor intensive. Everyone who does it that way made the decision to do so because it was uneconomical to do it any other way.

I could be more wrong, I could say the blender was lazy and stupid, although I do see your point

bank space could be an issue in many shops.

 

[flots am]

For those who say the blender is lazy for doing this, you cannot be more wrong. Partial pressure blending in the tank without a booster is extremely labor intensive.

Our shop does it every day and I have no idea what the "labor intensive" part is.

All it takes is a pressure gauge and a small app and no booster.

If your gas supplier isn't giving you O2 cylinders with enough pressure to mix 32%-36% in a used SCUBA tank, you need a new gas supplier.

flots.

 

[syntaxerrorsix]

Our shop does it every day and I have no idea what the "labor intensive" part is.

All it takes is a pressure gauge and a small app and no booster.

If your gas supplier isn't giving you O2 cylinders with enough pressure to mix 32%-36% in a used SCUBA tank, you need a new gas supplier.

flots.

O2 bottles are 2400 PSI. You can't do very many Al80's up to 32% without a booster or waste without draining the target bottle.

In case someone is unsure of the pros and cons.

http://www.nitroxmadeeasy.com/Methods.htm

 

[boulderjohn]

O2 bottles are 2400 PSI. You can't do very many Al80's up to 32% without a booster or waste without draining the target bottle.

In case someone is unsure of the pros and cons.

Different Methods to Make Nitrox

Correct.

You end up using several bottles, starting with the least full one first. I am not saying it's like a full day job, but speaking as someone who has done a lot of nitrox and trimix blending, it is the most labor intensive way I know to do it. I was just pointing out that the accusation that people are doing it because their too lazy to do it another way are off base. I did it that way when I had no choice.

 

[syntaxerrorsix]

Correct.

You end up using several bottles, starting with the least full one first. I am not saying it's like a full day job, but speaking as someone who has done a lot of nitrox and trimix blending, it is the most labor intensive way I know to do it. I was just pointing out that the accusation that people are doing it because their too lazy to do it another way are off base. I did it that way when I had no choice.

Yup, been there done that. Cascade and repeat. Multiple bottles on Friday at 5? Hope you brought beer or cash.

 

[dumpsterDiver]

I drain my tanks to zero for a fill, because the shop monkeys are too stupid to figure out how much oxygen to add to the mix. NOT dumping the left over nitrox saves money, saves oxygen and saves time, but it DOES increase the complexity and greatly increases the potential for error and it is not that practical if you are doing 5-6 tanks at the same time.

When I first started to do nitrox, I filled the tanks with oxygen in my garage and then took them to be filled with air. In order to save money, I would just figure how much oxygen I had to add to the mix to make it work and would never drain tanks until it was necessary and the oxygen bottle got too low. it makes your oxygen bottle last longer, a lot longer if you have a rich mix with 700 lbs in it and your next fill is a low mix.

 

[rddvet]

banked 32%, partial pressure blending for trimix (don't dive air)

Why wouldn't you partial fill the helium and then use the nitrox stick to fill the appropriate % nitrox over it? I'm not questioning you because I think you're wrong, I'm asking because I continuous blend nitrox at home but not trimix as of yet(not until I take the class). I thought it was preferred to either continuous blend trimix or pp the helium and top with nitrox as opposed to oxygen.

 

[nimoh]

Why wouldn't you partial fill the helium and then use the nitrox stick to fill the appropriate % nitrox over it? I'm not questioning you because I think you're wrong, I'm asking because I continuous blend nitrox at home but not trimix as of yet(not until I take the class). I thought it was preferred to either continuous blend trimix or pp the helium and top with nitrox as opposed to oxygen.

pretty much exactly what I do.

add oxygen (usually skip this step, since it isn't much when topping with 32), add the helium (boost if necessary), and top with 32%.

A nearby shop has an accublender where you can just dial in the O2 and helium percentage, and it will automatically regulate the source tanks to provide an accurate mix. A big advantage of this is there is no wait time or shaking needed before analyzing. When I mix myself, there is really no point in analyzing until driving to the dive site and having the bottles shaken during the drive.