{"id":8753,"date":"2026-09-18T06:50:23","date_gmt":"2026-09-18T06:50:23","guid":{"rendered":"https:\/\/www.simplybuyglobal.com\/?p=8753"},"modified":"2026-10-13T00:34:43","modified_gmt":"2026-10-13T00:34:43","slug":"pressure-transmitter-accuracy-calculation","status":"publish","type":"post","link":"https:\/\/www.simplybuyglobal.com\/es\/industry-knowledge\/pressure-transmitter-accuracy-calculation\/","title":{"rendered":"Pressure Transmitter Accuracy: How to Calculate Total Error"},"content":{"rendered":"

Quick answer:<\/h2>\n\n\n\n

A pressure transmitter accuracy calculation adds up the error terms that apply to your installation, converts each to a percentage of your span (the range you set), then combines them as a root-sum-square for a probable figure or a straight sum for a worst case. The printed datasheet number is only one term, measured at reference conditions, not the installed answer. Simply Buy is a multi-brand distributor and supply-chain integrator that helps buyers match models across brands, confirm what the manufacturer actually publishes, and quote the documents, stock status and Incoterm an order needs.<\/p>\n\n\n\n

Two quote sheets land on the same desk. One lists a flush-mount transmitter at “characteristics deviation < \u00b10.5 % of span”. The other lists a compact pressure sensor at “repeat accuracy \u00b11 % FS max” (a full-scale percentage). Both figures come from the manufacturer, and neither describes the device that will sit on your header at 55 \u00b0C after a year of service. That comparison belongs to procurement and engineering teams sourcing across brands.<\/p>\n\n\n\n

The method here ranks no brand on accuracy. It turns any published figure into one comparable number, total error at your own span and temperature excursion, then works through an example you can re-run and turn into an RFQ line.<\/p>\n\n\n\n

What Does a Pressure Transmitter Accuracy Figure Actually Tell You?<\/h2>\n\n\n\n

A datasheet headline figure is almost always a reference accuracy, not a single measurement. It bundles three effects: non-linearity (how far the output departs from a straight line), hysteresis (the difference between going up and coming back down) and repeatability (how closely repeated readings at the same pressure agree). Fuji Electric calls it the combined effects of the three “under these defined conditions” (Fuji Electric), and those conditions are controlled, usually a bench at a stable ambient temperature.<\/p>\n\n\n\n

Why Is the Headline Number Called Reference Accuracy?<\/h3>\n\n\n\n

Because it is measured against a reference, not your process. Vendors name the same idea differently: some write “basic accuracy”, and ifm publishes a “characteristics deviation” for its PG2799, so check what the vendor bundled in.<\/p>\n\n\n\n

What Does the Datasheet Leave Out?<\/h3>\n\n\n\n

Everything that depends on where it is installed. Fuji Electric lists five influences that push an installed transmitter off its reference figure: ambient temperature, static pressure, stability over time, supply voltage and mounting position. Supply voltage matters because the loop must keep the transmitter inside its operating window, covered in our 4-20 mA pressure transmitter wiring guide<\/a>. For gauge and absolute transmitters, the static-pressure effect is nil; for a differential-pressure device, it belongs in the budget. Our guide to the types of pressure sensors sorts out the families.<\/p>\n\n\n\n

What Is the Difference Between % of Span, % FS and % of URL?<\/h2>\n\n\n\n

Every accuracy figure is a percentage of something, and the datasheet does not always say which. Span is the gap between the limits you set; the upper range limit (URL) is the sensor’s maximum rated range.<\/p>\n\n\n\n

Printed form<\/th>Measured against<\/th>What re-ranging does<\/th><\/tr><\/thead>
% of calibrated span<\/td>the span you configured<\/td>percentage holds; absolute error shrinks with the span<\/td><\/tr>
%FS (full scale)<\/td>the device’s rated full-scale range<\/td>absolute band fixed by the rating, not your span<\/td><\/tr>
% of URL \/ max range<\/td>the sensor’s maximum rated range<\/td>percentage grows every time you shrink the span<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

On a fixed-range device, the rated full scale and the upper range limit are the same, so %FS and % of URL collapse into one. On a re-rangeable instrument, they differ, and that gap is where quote comparisons go wrong.<\/p>\n\n\n\n

\"Comparison<\/figure>\n\n\n\n

Why Does Re-Ranging Change the Percentage?<\/h3>\n\n\n\n

Pondus Instruments runs the arithmetic on a 0\u201310 bar gauge transmitter with a 0.1 % of max-range reference accuracy. The absolute band is 0.001 \u00d7 10 bar, or \u00b10.01 bar. At the full 0\u201310 bar, that is \u00b10.1 % of span; re-ranged to 0\u20131 bar, the same \u00b10.01 bar becomes \u00b11 % of span. The band never moved; the span shrank tenfold. Turndown is the ratio of maximum range to the span you use, so 10:1 means a span one tenth of full scale. Pondus notes its PT600 reaches 100:1 turndown. On a re-rangeable 4-20 mA pressure sensor, the base matters most.<\/p>\n\n\n\n

What Are the Five Terms in a Total Error Budget?<\/h2>\n\n\n\n

Total error is what the instrument does in service, not on the bench. Five terms cover the regular contributors, and each must be converted to the same base.<\/p>\n\n\n\n

Term<\/th>What it covers<\/th>When it applies<\/th><\/tr><\/thead>
Reference accuracy<\/td>non-linearity, hysteresis, repeatability<\/td>always, at the span you calibrate<\/td><\/tr>
Temperatura ambiente<\/td>zero and span shift across the excursion<\/td>always; from the vendor’s thermal coefficients<\/td><\/tr>
Static or line pressure<\/td>zero and span shift from line pressure<\/td>DP transmitters; nil for gauge and absolute<\/td><\/tr>
Overpressure<\/td>shift after a stated overpressure event<\/td>when the process can over-range the device<\/td><\/tr>
Stability<\/td>long-term drift over a stated period<\/td>sized by your calibration interval<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
\"Five<\/figure>\n\n\n\n

Two terms need unpacking. A thermal coefficient (TC) is the shift per fixed temperature step, usually quoted per 10 K, so a TC span of 0.15 % of span \/ 10 K means the span moves 0.15 % for every 10 K of change; TC zero is the same idea at the zero point. Long-term stability is drift over a stated period, often per year, and it decides how long a calibration holds.<\/p>\n\n\n\n

Vendors do not all publish the same list: InstrumentationTools uses five terms and splits static pressure into zero and span effects, while Fuji Electric publishes four, dropping stability. The two totals are not comparable, so use the list your data supports.<\/p>\n\n\n\n

Do You Add the Terms or Combine Them as a Root-Sum-Square?<\/h3>\n\n\n\n

Two rules turn the terms into one number.<\/p>\n\n\n\n