Pressure transmitter terminology 1

[Indy]

I have a question regarding a rose mount 3051s pressure transmitter. The primary range given by the supplier is -1 to 689.5 barg. I believe we require to measure 0-200 barg. The accuracy of the transmitter is 0.025% of span. My question is this span the primary measuring range or the required measurement span? I.e 0.2 barg or 0.05 barg ?

Thanks

 

[VEBill]

When the spec sheet for an instrument states "0.025% span accuracy", they're obviously referring to the span of their instrument. (Obviously the instrument supplier wouldn't know anything about your intentions.)

If this is written in some other context, such as a contract specification, then the correct interpretation may be something else. But that seems very unlikely, as they probably wouldn't reference span.

 

[danw2]

In the smart transmitter world, the reference accuracy applies to the configured span as long as the configured span is within a stated turn-down range. For the 3051S, that turn-down ratio is 10:1. Your 200 bar span is only 3.3:1 turn-down from the 690 bar max, so the 200 bar operating span is well within the turn-down range for the stated reference accuracy value to directly apply.

But you need to be very specific about which model you're talking about. I'm using the product data sheet found here:
Link

And you need to pay attention to the note (1) next to the performance class listing for the choice of ultra or classic. That note is on page 22 (pdf) and refers you to the reference accuracy table, where one finds that the range 5 is a 0.05% reference accuracy, not the 0.025% reference accuracy. (It is a game of specsmanship, as you know.)

The 200 bar span for your range 5 would be 0.05% of 200 bar, or 0.1 bar

That assumes that your model is "ultra" model and not the "Classic" model.

And you are should be aware that operating conditions (temperature, primarily) outside the range of reference accuracy conditions (approximately 20 Deg C and sea level barometric pressure) affects the operational accuracy; or as they say "your mileage may vary". Buried somewhere in the spec sheet are values for calculating operational accuracy at elevated or depressed temperatures.

 

[Indy]

Thank you for the replies.