Aircraft Coffee Maker Repair Bench Glassware Calibration

[dv8shane]

I recently was asked to look at a 2 station repair bench with digital voltmeter, thermocouple and meter, flow meter, pressure gauge and 3 analog ammeters for the 400 Hz 3 phase power coming at each station. It is used to repair aircraft coffee makers. I am looking for an opinion on flow meter calibration as it is the only item I can not do. the unit uses a glass tube type that has fixed markings. It has the initial values and correction factors etc in the accompanying documentation. I can not see how ground in lines on glass could change for calibration purposes.

Any thoughts

 

[J0anne]

Is wear and tear too simple an answer here as you need to verify the accuracy?

 

[dv8shane]

Is wear and tear too simple an answer here as you need to verify the accuracy?

Yes that is much too simple.

I am dealing with a piece of etched tubular glassware that has markings. As the flow increases the height of the water in the tube rises and is observed against the markings. It does have the original certification and I think it should be treated like a Fluke 50 turn coil. Once manufactured and calibrated it is not going to change significantly enough to make a difference to the process especially in this application.

 

[BradM]

Yes that is much too simple.

I am dealing with a piece of etched tubular glassware that has markings. As the flow increases the height of the water in the tube rises and is observed against the markings. It does have the original certification and I think it should be treated like a Fluke 50 turn coil. Once manufactured and calibrated it is not going to change significantly enough to make a difference to the process especially in this application.

I would agree with this. It would be nice to get some statement from the mfg. in regards to an interval, and possible expansion issues with the glass, etc.

I guess you could perform some verification by placing the container on a scale and using a stopwatch.

 

[dv8shane]

It turns out calibrating a simple piece is usually the hardest. I thought about it and I would have to design a system with a known volume by mass of water have an electronic start stop valve tied to counter for control of flow and a method of measuring the volume displaced taking into account the inside diameter of the tubes and acceleration from gravity at 0 PSIG, then I would have to do repeatability and reproduce ability to add the budget! ^&#%$#

 

[BradM]

What about putting a calibrated flow meter in line?

 

[dv8shane]

Still lots of work


I am going to suggest to the customer to remove the flow meters and send them out for calibration putting them on a 5 year interval it means down time but it looks like the best suggestion at this point

 

[BradM]

Still lots of work


I am going to suggest to the customer to remove the flow meters and send them out for calibration putting them on a 5 year interval it means down time but it looks like the best suggestion at this point

How much are the flow meters? Depending on the turn-around time they can purchase a couple a couple of spares and trade them out where there is little downtime.