2 questions

[Joe R.]

I have two questions:

1). Does anyone have any info on the 'nitrox sticks'? I had one shop owner tell me he had a 12% inaccuracy rate and went to back to partial pressure fills.


2).Has anyone heard of a case that holds handheld GPS for underwater use? Sounds too good to be true. Supposed to be good to 150'.I saw one advertised for $80.00

 

[The Chairman]

1) The only NitrOx stick I am familiar with has nothing to do with how you blend the NitrOx... it only measures O2. The variance indicated would then seem to be operator error.

2) I tried taking my GPS into the suds. You lose contact with the satellites before you hit 3 feet. Go figure! You can keep the sucker dry, but you need a gyroscope to navigate under water.

 

[DuckDive]

1). Sorry, no idea.

2). I'm reasonably sure that GPS sat signals do not penetrate water. In fact, there is at least one company that markets a product that uses GPS surface relay buoys to provide underwater fixes using sonar. I haven't been able to find any other kind of solution, and I figure that this one was developed because GPS doesn't work underwater.

I don't have the link with me right now, let me know if you want it.

 

[maddiver]

Joe- Never, ever trust what anyone tells you about the accuracy of fills (you should analyze you own cylinders *every* time). Also you should be familiar with the type and accuracy/history of the analyzer you choose to use. Is it the shop's? How well is it maintained? Sensor changed out, calibrated (you should always verify calibration as well....this may all be old hat to you? A 12 inaccuracy rate suggest inaccurate calibration or a sensor that is beyond its useful life. Smaller variations can occur with gas flow (make sure flow matches standards published by mfg for sensor). Never, never dive gas that is only 'partial pressure' analyzed. This can get you in big trouble quick...even with digital gauges.

Originally posted by Joe R.
I have two questions:

1). Does anyone have any info on the 'nitrox sticks'? I had one shop owner tell me he had a 12% inaccuracy rate and went to back to partial pressure fills.


2).Has anyone heard of a case that holds handheld GPS for underwater use? Sounds too good to be true. Supposed to be good to 150'.I saw one advertised for $80.00

 

[omar]

Joe,

I have found that there will be a small but definite difference between what is going into the compressor and what is coming out when using a blender such as the stik. I know of two other users of the Nitrox Stik and they have noticed the same thing. The difference is 1-2% lower on the high pressure side. If there is a difference greater than this it usually indicates that there is a leak in the system. On the whole if you use the inlet side analyzer to make sure you don't have too much oxygen going into the compressor and use one on the outlet side for the final mix indicator you can get very reliable and repeatable results. I can also give you the e-mail address of Ross Cowell if you want to ask him about it directly. (He is the guy who invented it.).

omar

 

[Uncle Pug]

#1. I don't have a nitrox stik but something similar in a nice S.S. and I calibrated my O2 flow gauge with a pressure head of 1500 psi... when the bank is lower than that the O2 percent reads a little low and when the fill gets closer to the high end the O2 percent is a little high. After a bunch of fills on the bank the analyzed O2 percent of the bank is still within 2 tenths of a percent of what I was shooting for. So I would say that 12% error is too much.

#2 "Sounds too good to be true." Well, I wouldn't be surprised if the military had something even better but you won't be buying it for $80.

 

[Joe R.]

Thanks for all the replies: I know I've seen the Nitrox Stik advertised, Immersed,Adv. Diver, How much is it? Is it something you could put on an existing compressor (ie Fire Depts) and just make Nitrox?
Uncle Pug can I get some more info on your set up?
Omar, It would be great if you could send me RC's email
Mad diver,Obviously you analize anything you breath(esp. Under water).
Net Doc. you will see more about the Stik, I'm certain.
Re. The underwater GPS, I'll find the ad and post the info asap. This was a case that held a Mag. 315 or 320 etc. Like I said 'it sounds too good to be true.

 

[Uncle Pug]

Originally posted by Joe R.
Uncle Pug can I get some more info on your set up?

Hi Joe,
There is a picture of it up on the board in some thread... I can't remember where... maybe someone else does...

Basics:
RIX SA6B oiless compressor.
Blender is SS and has a venturi inlet where the O2 and He are injected. Inside the body of the blender are two delrin baffels with offset holes. On top of the blender I have a large ball valve and a large filter. When pumping argon I can shut the air intake off so only argon is feed into the compressor.

The O2 and He supplied to the blender are controlled by needle valves and flow gauges after stepping down the pressure to 50 psi with a regulator.

The post compression analysis is regulated off of the fill manifold and fed to an O2 and He analyzer.

I have heard of one shop that had an explosion using continuous blending.

One thing I need to add is a solenoid O2 and He shut off tied to the compressor... got any sources for me Omar?

 

[Zept]

1. Put GPS unit in waterproof box.

2. Put satellite phone in waterproof box.

3. Dive.

4. Surface a gazillion miles from anywhere.

5. Call the boat with your location.

I guess you could put a GPS receiver on your dive float and run a cable down to an underwater display, but it would be absurdly cumbersome.

I keep seeing ads for the EyeSea underwater sonar system, made by XIOS. Find it hard to believe that many people are buying them, though.

Personally, I think my tilt-tolerant compass is the height of technological sophistication.

Zept

 

[FredT]

If what you're talking about is a "preblender" for an oil-less compressor the slickest I've seen is a 4" pipe about 3' long full of "marbles". These can be ping pong balls, SST bearings, glass or plastic beads, etc. provided the diameter is less than 1/4 the pipe ID, the smaller the balls the less pipe length you need, but the more restriction on the gas flow. I'd prefer to stay between 1/4 and 1/8 of pipe ID for ball diameter. O2 goes in through a meterng valve alng with the incoming air at one end, O2 sensor mounted in-line between the end of the ball stack and the compressor. The marbles provide a "many turns" static mixer to give a homogenous gas at the O2 sensor. The O2 sensor provides a method for continous monitoring and shortest possible feedback loop close to the gas input point for minimal variation in the final compressed gas.