Design Manual › Instrumentation & control › Range & accuracy
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Instrument Range & Accuracy Selection
From process value to the right model: where your normal reading sits on the range (40–70 % FS is the golden
band), the real error at that point — the %FS trap — and a use-based verdict (process control vs compliance) with the exact
catalogue model to order. Built for wastewater online analysers in the tropics.
1Process duty
Results — range, operating point, error, model
Operating point
—%FS
Error @ normal
—
Peak headroom
—
| Item | Value | Rule / limit | Status |
|---|
2Why %FS bites at the low end
For a %FS instrument the absolute error is constant across the whole span.
Operating low on the range turns that fixed error into a large fraction of your reading.
| Reading as % of FS | 50 % | 25 % | 10 % | 5 % |
|---|---|---|---|---|
| Relative error × (headline accuracy) | — | — | — | — |
Order this duty
| Item | Model / spec |
|---|
Quote this duty's analyser at factory price
The model below at the manufacturer's ex-works price — our margin comes solely from the export tax rebate. This sheet gives you the range and the error to defend the choice to your reviewer.
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Sources & parameter basis
| [1] | Sino Analyzer accuracy guide — golden rule (operate upper half / two-thirds of span) with the 0–500 vs 0–100 bar ±0.5%FS example (3.6 % vs 0.7 % relative). |
| [2] | E+H / Jade Ant flow sizing — normal 40–70 %FS, min >10 %, max <90 %. |
| [3] | Dataweek %FS vs %RD; LORRIC dual-region accuracy (>20 %FS %reading / <20 %FS floor); Merobix %span low-end amplification. |
| [4] | Jiuyuhub published product data — DO6000Y 0–20 ±1%FS; DO6000M 0–25 ±1%FS; PH6000C −2…16 ±0.02 / ±1999 mV ±5 mV; MS6000SG 0–5000 mg/L↔0–50 g/L; SE10A ±0.5 %; SE11E ±0.5/0.3/0.2 %. |
Full derivation and worked examples: Instrument-Range-Accuracy-Calculation-Sheet.md (Unit 3 of the I&C manual).
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