Best material for building a blending stick.

[Richard Harvey]

I have been partial pressure blending (tri mix) for a number of years now but have decided to build a blending stick
Before doing so I have a few questions.
I am using the oxidation hacker to start with and have read a lot of forums. A few years back I saw a big debate about what material to use. Stainless was considered the best but if using plastic which is best. ABS or PVC?

Second question is if anyone has had success doing a single stick for trimix to keep the size down. I will be using this on my charter boat so being able to have a smaller unit would be good. I have seen a comercial unit that does this. Two barbs in one stick, add O2 to bring it up to 36% and then add helium to bring it to desired mix (ie 21/35)

 

[michael-fisch]

No way can you get 21/35 by mixing He and a nitrox 36..
All DIR standard gasses can be made by mixing He with a 32% Nitrox ie: 21/35, 18/45 and 15/55

Michael

 

[Richard Harvey]

No way can you get 21/35 by mixing He and a nitrox 36..
All DIR standard gasses can be made by mixing He with a 32% Nitrox ie: 21/35, 18/45 and 15/55

Michael

Yup. I typed in the wrong number nitrox 32 is the standard mix. Brain fat due to the -25 weather out side. But that's not my question. Question is what type of material (pipe) and can it be done in a single mixing stick. My assumption is no big difference between PVC and ABS or I would have found info on that (other than very old threads where people debate it with no science) and I also assume there is a reason for doing a two stage mixing stick or again I would have found people doing the single mixer.

 

[michael-fisch]

No idea, but since friends use PVC for their sticks and it's easy to glue things to PVC, I'd go with PVC. Unfortunately with either plastic it's easy to build up a static charge, sparks and O2 are a bad combination. It might be a good idea to glue aluminum foil on the inside of the plastic tube and ground it to the hull.

Michael

 

[Richard Harvey]

No idea, but since friends use PVC for their sticks and it's easy to glue things to PVC, I'd go with PVC. Unfortunately with either plastic it's easy to build up a static charge, sparks and O2 are a bad combination. It might be a good idea to glue aluminum foil on the inside of the plastic tube and ground it to the hull.

Michael

Yes for one the boat I will use a static grounding plate

 

[rjack321]

ABS is cheaper in small pieces/sections from the plumbing section. It glues to PVC end fittings fine

 

[clownfishsydney]

I built mine from PVC about 10 years ago, still as good as new.

 

[OkByMe]

I have been partial pressure blending (tri mix) for a number of years now but have decided to build a blending stick
Before doing so I have a few questions.
I am using the oxidation hacker to start with and have read a lot of forums. A few years back I saw a big debate about what material to use. Stainless was considered the best but if using plastic which is best. ABS or PVC?

Second question is if anyone has had success doing a single stick for trimix to keep the size down. I will be using this on my charter boat so being able to have a smaller unit would be good. I have seen a comercial unit that does this. Two barbs in one stick, add O2 to bring it up to 36% and then add helium to bring it to desired mix (ie 21/35)

You can buy a gas turbulator cheap and incorporate in into the compressor intake with a solenoid to shut off the other gasses when the compressor goes down.

Pictures:

Another:

And another:

 

[grf88]

ABS is readily available in any hardware store in Ontario and works fine, in fact the thicker wall thickness is an advantage when installing the inlets and sensor.

 

[rjack321]

Helium and O2 input into the same stick is a pita and even with precompression analysis at the bottom of the stick you end up chasing the percentages back and forth and constantly tweaking the helium and o2 as the pressure rises. Not recommended.

Use a pre stick for the helium,
analyze the O2,
then add the o2 and mix again in a second stick
analyze final o2.