The Great Helium Hunt of 2021

[admikar]

I just paid 350 usd for a T here in Croatia, is that good or bad in US standards?

It's 460€ in your neighbourhood, so, I'd say it's good price.

 

[Sevenrider860]

I don't know what CB stands for but I'm assuming you mean a booster yeah?



I for one did not know, so thanks.

CB Compressor…Continuous Blend. AKA Nitrox Stick for Trimix.

 

[Wookie]

I don't know what CB stands for but I'm assuming you mean a booster yeah?

No. A booster scavenges down to about 300 PSI (rule of thumb, Tbone will be along shortly to tell us how he scavenges down to 200 PSI). CB is constant blending, where you run the cylinder down to where the blending regulator no longer provides accurate flow, usually about 25-50 PSI. You can actually run to 0 PSI but your regulator isn’t accurate at very low pressures.

 

[rob.mwpropane]

No. A booster scavenges down to about 300 PSI (rule of thumb, Tbone will be along shortly to tell us how he scavenges down to 200 PSI). CB is constant blending, where you run the cylinder down to where the blending regulator no longer provides accurate flow, usually about 25-50 PSI. You can actually run to 0 PSI but your regulator isn’t accurate at very low pressures.

Nice, thank you for the explanation. Do you run He directly through the compressor? A little scary as it heats up the heads, correct?

I am 90% done my nitrox stick, just need to get some O2 tubing to run from the regulator to the stick, everything else is ready. I don't think I'll be messing with He anytime soon, but I still like learning.

 

[Wookie]

Nice, thank you for the explanation. Do you run He directly through the compressor? A little scary as it heats up the heads, correct?

I am 90% done my nitrox stick, just need to get some O2 tubing to run from the regulator to the stick, everything else is ready. I don't think I'll be messing with He anytime soon, but I still like learning.

Run it directly into your nitrox stick. You don’t want it directly into the suction because it will stream and I would worry about cracking a valve.

I had a membrane system that I could feed He into that was metered and regulated, just like a nitrox stick. I ran my regulator to about 25 PSI and flow (using a Dwyer flow meter) up to 10 CFM depending on the mix required.

 

[rob.mwpropane]

Run it directly into your nitrox stick. You don’t want it directly into the suction because it will stream and I would worry about cracking a valve.

I had a membrane system that I could feed He into that was metered and regulated, just like a nitrox stick. I ran my regulator to about 25 PSI and flow (using a Dwyer flow meter) up to 10 CFM depending on the mix required.

That's what I meant, through the stick. I have a dwyer flow meter... one day I'll get into He.... then again with prices one day I might get into RB's, lol.

 

[Tracy]

Nice, thank you for the explanation. Do you run He directly through the compressor? A little scary as it heats up the heads, correct?

Yes and no. At nominal blends and pressures, the head temps actually run cooler.
Running 21/35 at 3500 psi, my heads will tend to be 10-20 degrees cooler than with 32%.
10/70 runs about 20 degrees warmer.
10/70 at 4500 causes lots of temp related issues. Valve life is drastically shortened.

 

[kensuf]

It probably is, I seem to remember 21/35 coming out to about $1.20 a cuft.

For those that don't know 21/35 is created by mixing 10/70 and 32% at a 1:1 ratio. 18/45 is 2:1 10/70 to 32%. IIRC 30/30 is 1:2, though don't quote me on that.

The first one is correct, the second one is off by a small factor (it's more like 5:3) and you'll never get 30/30 by mixing only 10/70 and 32%.

 

[CptTightPants21]

It probably is, I seem to remember 21/35 coming out to about $1.20 a cuft.

For those that don't know 21/35 is created by mixing 10/70 and 32% at a 1:1 ratio. 18/45 is 2:1 10/70 to 32%. IIRC 30/30 is 1:2, though don't quote me on that.

That's a little confusing.

All standard gases (except 30/30) are made by filling the cylinder volume with the desired percentage of helium and then filling the remaining volume with 32%.

21/35 is created by filling tank 35% with helium, and 65% Nitrox 32.

12/65 is created by filling tank with 65% helium and 35% Nitrox 32.

32% is created by adding 14% pure O2 and 86% air.

It means that if I have a tank of 21/35 filled to 1200 and I need it refilled to 3600. I don't need a trimix mixing app. All I have to do it

.35 x 2400psi (3600-1200) = 840
.14 x 2400 pure O2 = 336
Remaining volume with air to 3600psi.

 

[rob.mwpropane]

I have a hopefully not so dumb question. When filling from a compressor let's say I want 32%. So I figure to fill a set of 3500 tanks to 3900 (because they'll cool and I like more gas) I need to add ~ 543psi of O2. I do this and the tanks get a little warm, I pump up to 3900, shut things down and let things cool off. Will I still have my desired 32% when things cool down. I would expect somewhere around ~ 3600 or so? And if so, why would it still be correct? My final pressure isn't 3900.

I actually did this the other day (was shooting for 28%). Even after the tanks cooled down I still ended up having what I wanted within .2 of 28%. I was unsure whether I would have to top them off after they cooled but I did not.

I'm sure there are some physics here that I'm just not grasping.