There is documentation online on how to connect a soda stream to a large CO2 tank. I was wondering if this could be done using using tank with 'beer gas', co2/nitrogen, mix and would give the Guinness bubble effect to whatever you infused (coffee, water, beer,etc)?
DO NOT use a CO2/Nitrogen mix in combination with equipment designed for CO2!
The pressure of the CO2/N2 mixture is much higher, and using cylinders and/or pressure regulators and gauges designed for CO2 can rupture and explode, leading to injury or death.
Sodastream, paintball gun and fire extinguisher cylinders are all rated for CO2 pressures only.
If you want to use CO2/N2 mixtures use cylinders, ONLY USE pressure regulators and gauges designed for that mixture.
Beer gas is designed to push beer in lines that are really long. Where using just CO2 would over carbonate the beer in the lines. The CO2/nitrogen blend doesn't infuse into the beer much allowing much higher pressures.
To get that stout head you need a special tap.
There's a lot of coffee shops pouring with nitro for that creamy thick head.
Attaching beer gas to a soda machine would pour flat soda compared to CO2. Because it mixes syrup water and CO2 on the fly, and beer gas doesn't carbonate much.
I suspect if you had a keg of ready to drink soda (mixed and carbonated) and pushed it with Beer gas using a stout tap. It may give you a similar head to a stout though would dissipate quickly not having the proteins to let it persist.
Sodastream uses cool water and a syrup that you carbonate with the pressure from the CO2 and the bottles that seals tight to the device.
Using other liquids (like wine or flat beer) in a soda stream causes ceilings to change color. I am not sure of coffee will work either. So before you do any changes to your machine, go outside and test if you can carbonate your drink of choice.
Regarding BeerMix, I think you stand a chance of causing a lot of damage. As @EvilZymurgist pointed out, beermix is a bit different from CO2. For one, you will need a special regulator as the gas is at a higher pressure than CO2 and you will need a special tap that can work at such high pressures. As a Sodastream is made to handle CO2 pressure, I believe that you may be putting yourself at night pushing a higher pressure gas through the machine.
If you really want to pour coffee or any other liquid using nitro, get the proper dispensing setup and the kegs. Fill the kegs with your choice and have fun. And if you do not want your liquid to be carbonated, buy the beermix with the least amount of CO2.
@Evil Zymurgist, in response to your comment:
You're not wrong, but you could be more right. When comparing the effects of CO2 with that of N2/CO2 mixtures on the head, we're looking at both head formation (which is a factor of carbonation) and head density and retention (which is more a factor of beer foam mechanics).
You are correct in that gas pressure (be it CO2 or a N2/CO2 mixture) is the driving factor in head formation.
However, it is the N2 that is responsible for the creamy head on ales (most typically stouts) because N2 bubbles are much smaller than CO2 bubbles (for reasons involving a lot of physics) and thereby cause a denser foam that consists of less gas and more beer and foam-positive compounds. Also, because the partial pressure of N2 in the atmosphere is dramatically large than that of CO2, the N2 content in the head is much closer to equilibrium, which keeps the bubbles in the foam rather than allowing them to escape, pop, and vent off into the atmosphere.
The stout or nitro tap to which you refer is essentially a flow controlling faucet or nozzle which makes for a very slow pour that allows the nitrogen to come out of suspension in a controlled manner (unlike CO2 nitrogen is not in solution, being for all intents and purposes water-insoluble) that allows a thick, creamy head to build without causing excessive foaming.
You are absolutely correct in your statement that kegs should not be overpressurized in order to avoid overcabonation. However that's not what we were discussing here. :-)