Question O2 sensor calibration

[LFMarm]

Depends on the orientation of the flow, laminar vs turbulent, fill & exit rates, etc. I agree for low enough flow it's negligible, but aren't we talking about manual addition?

Not manual addition – the head is fed from LP hose and the amount of flow depends on how much you open the tank valve.

 

[inquis]

Not manual addition – the head is fed from LP hose and the amount of flow depends on how much you open the tank valve.

Sounds manual to me. If you wait until they merely stabilize, you don't know whether or not they're inflated by flow. Don't you still have to turn it off and confirm the readings didn't change?

 

[LFMarm]

Sounds manual to me. If you wait until they merely stabilize, you don't know whether or not they're inflated by flow. Don't you still have to turn it off and confirm the readings didn't change?

Agree with you and also why I am not a fan of this procedure. I was taught not to turn off the very slow flow and calibrate when reaching stable max.

 

[Dsix36]

I am in complete agreement with you about calibrating and the usage of caps but your statement that flow equals pressure is literally completely wrong; pressure drops with flow.

See the Bernoulli Principle. Flow rates while calibrating are very low so I would expect the difference To be negligible but Flow is not increasing pressure.

I am correct in my example. Flow will equate to pressure if there is insufficient bleed off (or too much flow). Any analyzer that requires x amount of flow will show a higher reading when the flow is increased more than then bleed off will handle. If you do not believe me, try analyzing with continuous flow, then block the bleed hole and watch the reading increase with the increased pressure from the flow still going in.

 

[LFMarm]

I am correct in my example. Flow will equate to pressure if there is insufficient bleed off (or too much flow). Any analyzer that requires x amount of flow will show a higher reading when the flow is increased more than then bleed off will handle. If you do not believe me, try analyzing with continuous flow, then block the bleed hole and watch the reading increase with the increased pressure from the flow still going in.

These sensors do not require flow. They are tested in lab in sealed vessels.

 

[Dsix36]

These sensors do not require flow. They are tested in lab in sealed vessels.

How will you ever get the loop flushed with O2 for the calibration without flow? Yes, the actual calibration is done in a sealed environment (flushed loop in most cases) BUT is still needs to be a ambient pressure. You seem to missing the point here. If you calibrate with positive pressure in the loop, it will not be accurate as the readings will be higher than they should be and when the pressure is released it will drop accordingly.

 

[rjack321]

How will you ever get the loop flushed with O2 for the calibration without flow? Yes, the actual calibration is done in a sealed environment (flushed loop in most cases) BUT is still needs to be a ambient pressure. You seem to missing the point here. If you calibrate with positive pressure in the loop, it will not be accurate as the readings will be higher than they should be and when the pressure is released it will drop accordingly.

Just vent from the DSV and it'll be at ambient