Pressure Measurement · Glossary

What is Upper Range Limit?

Symbol: URLsensor maximumPressure Measurement

Upper range limit is the highest value a transmitter sensor can be calibrated to measure.

Upper Range Limit Explained

A transmitter model covers a sensor range from its lower range limit (LRL) to its upper range limit (URL). Within it you set the calibrated range: lower range value (LRV) and upper range value (URV).

Accuracy is often stated as % of span but with extra terms in % of URL, so a small span on a large sensor loses accuracy.

Upper Range Limit Formula

Span = URV − LRV and Turndown = URL ÷ Span

URV, LRV	upper and lower range values set at calibration
URL	upper range limit of the sensor

Example: URL 100 bar, calibrated 0 to 10 bar: span 10 bar, turndown 10:1.

Calculators for Upper Range Limit

CalculatorTransmitter Turndown CalculatorFree online calculator with formula and worked example.CalculatorTotal Probable Error CalculatorFree online calculator with formula and worked example.

Frequently Asked Questions

What is Upper Range Limit?

Upper range limit is the highest value a transmitter sensor can be calibrated to measure.

What is the difference between URL and URV?

URL is a fixed limit of the sensor. URV is the value you set for 20 mA, which must be at or below the URL.

Can the LRV be negative?

Yes, down to the LRL, for example for vacuum or elevated zero ranges.

Learn more on the blog

Instrumentation and control standards

A practical guide on instrumentationblog.in with more detail on upper range limit and how it is applied on real plants.

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