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Engineering Toolbox/Range / Span / Rangedown

Instrumentation & Configuration

Range / Span / Rangedown

Check whether a configured transmitter range sits inside the sensor limits and calculate configured span, range utilization and rangedown/turndown.

Transmitter range

Use the range limits and minimum span for the exact sensor/range code from the instrument datasheet.

Enter the nominal/reference span used by the OEM rangedown specification. Do not infer this from a bipolar LRL/URL unless the datasheet defines it that way.

Normally the 4 mA range value.

Normally the 20 mA range value.

Optional. Use only a published value for the exact sensor/range code.

Field use

Useful before reranging a smart transmitter.

Confirm that the intended 4 mA and 20 mA values are inside the selected sensor limits and that the configured span is not below the manufacturer's permitted minimum span.

Calculation basis

Sensor range-window span = URL − LRL
Configured span = |URV − LRV|
Rangedown = OEM reference span ÷ configured span

Some manufacturers use rangedown; others use turndown or span adjustment. This tool reports the geometric ratio only.

A mathematically valid ratio does not guarantee the same reference accuracy, total performance, stability or flow performance at that range. Always apply the exact OEM datasheet for the installed sensor/range code. Reverse output direction also requires device support.

Continue in Instrumentation & Calibration

View category →
4–20 mA Signal Scaling Convert loop current to percentage of span and engineering units, or calculate the expected mA from a process value. 3–15 psi Pneumatic Signal Convert a standard pneumatic control signal between psi and percentage output without hiding underrange or overrange conditions. Five-Point Calibration Check Evaluate 0, 25, 50, 75 and 100% points against a defined tolerance in percentage of calibrated span. Calibration Error Calculate signed error in engineering units and percentage of span, with a clear pass/fail result against tolerance.