New Nitrox Stick Question

[dchango]

How much is too much resistance on air draw into the compressor? I built a nitrox stick 2”x 24” basically the Oxyhacker’s design (great book). I know there is going to be some resistance, but while breathing through it I can really feel the difference when I unplug the ½” part on the tee where the sensor screws in. I know there has been hundreds of these built with probably little to no compressor problems. I have a Coltri MCH16 Compact and running a 1 ¼” corrugated hose to the stick. Just curious.

Thanks
Damon

 

[rcontrera]

We use 2" hose to feed from our Nitrox generator and that is under pressure. I think that you should go with the largest hose you can get (within reason) since back pressure will cause the first stage to heat up. In the Compact, you really don't want the added heat because the sound deadening also acts a little like an insulator.

 

[NAM001]

how long of a hose are you using
without looking it up how large of a compressor 3 cu ft.
i have a rix 6 and am using the factory sized 3/4 id " i think and it is pumping fine the hose is 10 ft or so. my stick has no resistance that i can tell,,, however the restriction to 1/2 and being partially blocked by the sensor may be of some concern. i am guessing that you have perhaps too many restrictions n the like. can you get a pvc piece (for your sensor) that the hose can be put inside of instead of around? you can eliminate 2 restrictions that way.

How much is too much resistance on air draw into the compressor? I built a nitrox stick 2”x 24” basically the Oxyhacker’s design (great book). I know there is going to be some resistance, but while breathing through it I can really feel the difference when I unplug the ½” part on the tee where the sensor screws in. I know there has been hundreds of these built with probably little to no compressor problems. I have a Coltri MCH16 Compact and running a 1 ¼” corrugated hose to the stick. Just curious.

Thanks
Damon

 

[dchango]

Thanks for the quick responses. The opening in the back will only fit 1 ¼’ or smaller hose. I used the corrugated hose because it had a larger inside diameter then the other hoses that I found. The intake filter housing only has roughly a ¾” opening on it. I had to use a bushing and make it bigger to accommodate the 1 ¼” hose. I am running about 10’ of hose from the compressor to the stick and the compressor is a 9 CFM.
Thanks
Damon

 

[NAM001]

the 9cfm exlplains the large intake hose. is it safe to assume the 1 1/4 is outside diameter? that makes the id near 1". you can always shorten the hose to a min length and use the largest fitting on the output of the stick to accomodate the hose. it is troubling that you get a significant resistance with the sampling T in the line. T T is where i think you need tomake the major change at.

 

[rcontrera]

The opening in the back will only fit 1 ¼’ or smaller hose.

Hmmm ... the last MCH16 Cabinet that I worked with had several knockouts under the foam to work with. The 2" hose was no problem to pass through the rectangular knockout.

Oh ... also make sure that your inlet filter on the stick is rated for the proper flow.

 

[Peter_C]

What is the O2 reading difference between running and not running when just pumping air?

 

[dchango]

Ray there is only one hole in the back of the unit. I measured the ID of the hose and it measures1 ½” not 1 ¼” as I stated before. The hose barb that I used on the bottom ofthe stick is a 1 ¼”. Peter I haven’t hooked up the O2 meter to it yet, as I’m still in the process of building that too. This all is a work in process.
Thanks
Damon

 

[rcontrera]

Ray there is only one hole in the back of the unit.

You can turn it into a larger hole a LOT easier than making it into a smaller one. Tin snips are your friend!

 

[dchango]

Well, I finally got it completed. I started over completely. Instead of using the 2 inch PVC pipe, I used a 4 inch ABS pipe. The other modification to the stick was rather than using baffles I used practice golf balls with the holes in them. I filled the stick up about three quarters of the way it took 48 golf balls. At first, I just used the golf balls, but noticed it made a direct path going all the way through which I could see through to the bottom of the stick. Being inside the pipe was round and the golf balls were round they fit evenly and made a clear path going through. I decided that I would use some pieces of wire mesh and layer the golf balls. Being the golf balls are not stacked on top of each other now there was no straight path through the stick (I even crushed a few just so they were not completely round).

I finished assembling the stick. I then tested the resistance in the stick by breathing through it again, there was little to no resistance that was in the other stick. I felt that I was on the right track now. I plumbed the stick back to the compressor with some corrugated pool hose, which is about 10 feet long. I also completed my El Cheapo II analyzer (which was also fun to build). I set the meter to 20.9 and fired up the compressor. The meter didn't move it still read 20.9, which was a good sign. The next test was to pump some 02 through it without it blowing up:shocked2:. I cracked the valve and started increasing the flow and watched the meter start going up. I had one of my fill whips cracked open with my other meter analyzing the gas coming out. I got it up to 32% on the stick meter and the meter on the whip read 31.6. Which I'm happy with that, so I think my little project was a success. I can't wait to start pumping some nitrox, I will try to post a picture of it. Thanks for all your help.

Damon Chango