Section III and Digital Pressure Gages

[GLS Chief]

Hi,

I am looking for clarification on how to apply ASME requirements for pump hydro testing.

First is to make sure I'm applying the low limit for the usable gage range from Section III, "Digital type pressure gages may be used without range restriction provided the combined error due to calibration and readability does not exceed 1% of the test pressure."

My example is that I have a High-Accuracy Digital Pressure Gauge 0-5000 @ .10% FS with a 2 decimal readability. So I calculate I can use it for testing above 501# - Do I have that right?

Second question is about building to an older code version before the digital pressure gage part was added. Is there anything that amplifies using the newer criteria for digital gages on those tests or are you locked into using the analog requirements?

Thanks

 

[JR97]

GLS Chief,

I agree with your math on the usable range. You will need to verify the low point of what you call the usable range when you do the pre-test calibration. What we have found is we are able to calibrate to a usable range of about 1/2 what the published accuracy would indicate. As the gage wears, the lower limit of the usable range tends to increase. When it gets too high it is time to replace the gage.

I do not have a position on your second question.

JR97