XPost: alt.home.repair   
   From: xxx@yyy.zzz   
      
   On 2022-12-10 20:30:08 +0000, Paul in Houston TX said:   
      
   > This is my guess:   
      
   Thank you for these ideas as I first have to figure out how the sodastream   
   works, in order to replicate not only the nozzle but the pressure used.   
      
   My original guess was that the sodastream is regulated, but almost   
   everything on the net says a sodastream has no regulator - so it appears   
   that the CO2, surprisingly so, is nominally injected at 870 psi (68C/154F).   
      
   Given a 1L coke bottle will burst at just over 190 psi (ask me how I know   
   this), and given even the sodastream bottles will burst at about 320 psi,   
   the sodastream seems to incorporate a pressure overflow which is heard and   
   felt as a burp when the requisite head pressure is acheieved in the bottle.   
      
   I'm guessing that burp head pressure relief valve on the sodastream is set   
   to the order of somewhere around 25 psi to not much more than that I think.   
      
   > Think about a CO2 gun.  Pulling the trigger does not   
   > empty the entire cartridge.   
      
   I don't have any experience with a CO2 gun, but that brings up a new idea   
   that maybe there is a CO2 gun out there that will do what sodastream does?   
      
   > The needed CO2 fills a known volume.  The   
   > volume has check valves in front and behind the volume.  When you pull   
   > the trigger it opens the forward check valve causing the CO2 to go down   
   > the barrel.   
      
   It's a good idea to maybe approach a solution by injecting a known volume.   
      
   I have nothing against the idea of injecting a known volume of CO2 since it   
   makes perfect sense to approach it that way - but - I think the sodastream   
   volume is only dependent on two things, one of which is how long you hold   
   the button down, and the other is the burp overflow pressure (see above).   
      
   As far as I can tell from Internet searches, when you press the sodastream   
   button down, all it does is depress the valve inside the canister which   
   lets the carbon dioxide gas at the top of the canister vent into the water.   
      
   > Since the pressure is now less than the cartridge it causes   
   > the cartridge check valve to close until some other action causes it to   
   > open (moving the lever on the gun or the handle or button on the SodaSteam.   
      
   I think that's a perfectly practical known-volume method of CO2 insertion,   
   but there's nothing I can find that shows the sodastream using that method   
   directly.   
      
   Of course, the sodastream manual says to use short bursts, which itself   
   causes a known volume to swirl inside the container, and the sodastream   
   says to stop when the headspace overflow pressure valve bursts with a burp.   
      
   > If I were to make a soda device I would use a small pipe that is   
   > inserted into the liquid so that the instantaneous release of the   
   > calculated volume would be injected into the liquid causing the liquid   
   > to swirl and foam.   
      
   I would do the same except that you don't want the foam.   
   The suggested carbonating stones appear to do just that.   
      
   But paradoxically, the sodastream seems to inject the carbon dioxide at a   
   millimeter or two ABOVE the water surface! Why? I don't know. But it works.   
      
   >  Use of electrical solenoid valves would be tempting.   
      
   There is a sodastream model that is fully automatic & requires 120VAC.   
      
   >   The volume would have to be carefully calculated.   
      
   I think the way the sodastream handles the volume is by the burp pressure.   
      
   > It would not be much, just a few CC's.   
      
   Amounts for a gas (even for a dissolved gas perhaps?) aren't really   
   usefully measured in cc's but in weight due to inevitable pressure &   
   temperature changes affecting the volume (pv=nrt stuff from school).   
      
   >  You could probably figure it out from the max   
   > absorption of CO2 in water at a certain temp and pressure.   
      
   Since a 410 gram sodastream canister is widely reported to fill 45 liters   
   in practice, it's just a gram under 10 grams of carbon dioxide per liter,   
   maybe even as much as 2 grams under 10 grams due to inevitable waste.   
      
   The question is where to get that air gun that will have a pointy tip?   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)