Oxygen tester????

[Capnsnott]

Great advice, thanks! I was wondering what would be a good storage device.

 

[TTSkipper]

I can't take the credit for the film can, I read it on this board or one of the other ones.

 

[s7595]

dr frankenmule
what tools did you use
need to see if I have all the rite toys
love my tools

 

[Capnsnott]

I used a straight edge and pencil to mark the locations and sizes of the holes.
Then I used an exacto knife to make the round holes and small holes for the power scroll saw blade to slide into. I have one of the bench top power scroll saw units, it's fast and easy to use.
After I cut the holes for the meter and switch, I used a small flat file to clean the burrs off.
The exacto works better on plastic than a drill bit since you don't have to put much pressure on it (you won't break the plastic case) and you get a tighter hole too.
For soldering, I used a 15 amp pencil tip unit. You have to remove a tiny resistor from the panel meter, and a higher amp unit will de-solder the pad used for attachment. I also use .032" high tech solder. It flows and works 100% better than standard solder and it's cheap.
While I did the work on the case, my soldering iron was heating. I had everything laid out in it's basic position. It helps having used these panel meters before, so I knew my way around them. I also like to solder things together when they are installed in the case. It allowed me to see just how much wire to use.
I really would liked to have a smaller case. This one is big enough to fit two of everything in it and it is just a bit too big to fit in the smaller dry boxes.

Patrick's layout/instructions are VERY EASY to read, anyone can put one of these together.
Hope this helped.
Greg

 

[gbrandon]

As a member of our Fire Department's HazMat team, we maintain and repair our "fleet" of gas detectors, roughly 50 units, with about 25 of those being 4-gas meters that detect Oxygen. So, I've gotten to see alot of their little quirks.

First off, the sensor cell is a consumable item, just like tires on a car. From the time it's manufactured it has a lifespan. In the best of cases, the best oxygen cell I've seen, manufactured by CitiCell (British) will last about 2 years.

There's lots of things that reduce that lifespan. Use is a big one; using a meter twice daily for about 15 minutes per use will cut life in half. Some meters that are used heavily I have seen beyond span limits in 6 months. Another is contaminates; exposure to a variety of acids, bleach or other oxidizers such as hydrogen peroxide can poison the sensor cell.

Calibration of the meter is important. The most commonly used calibration gas is atmospheric air. We use synthetic air, hideously expensive at $240 per 200 cu. ft. cylinder, at exactly 20.095%. Oddly enough, we can calibrate a meter to this standard, then walk outside in the winter and see 20.1% in the atmosphere. This is from the inversion layer we often get here. And at a class where everyone looked and acted sleepy, we pulled out a meter...19.6% Oxygen! No wonder people were nodding off. So the moral is, be sure of where you calibrate the meter.

Since the sensor cells operate by how much oxygen drive (partial pressure) exists, the sensing conditions are pretty important, too. We use calibrated flow meters to deliver gas. You can turn the knob from 1 lpm to 2 lpm and watch the O2 % change. There are other variables we control for calibration, also, such as temperature and humidity. Not to mention battery voltage.

The good news is that we have seen, with careful maintenence and calibrations, meters that reliably produce repeatable readings with accuracy +- 0.05% over months.

Yes, it's worth your life to have your own meter. Just give it the maintenence and care in use you would have for any other piece of life support equipment.

All the best, James

Your telling me that .5 percent difference in the oxygen content in the air made the people in the class sleepy? Id like to see some data that shows at what percent oxygen degradation does symptoms like "sleepyness" etc, appear. I Find your statement hard to believe.

 

[d33ps1x]

Some pics of the El Cheapo II:

I bought mine with the Exhaust tee and DIN flow restrictor.

 

[Capnsnott]

Ours look the same on layout, but I put the 1/8" plug on the right side of the case. I'm going to build another one using a smaller box.