{"id":100200,"date":"2026-02-15T20:26:24","date_gmt":"2026-02-15T20:26:24","guid":{"rendered":"https:\/\/vibromera.eu\/?post_type=calculator&#038;p=100200"},"modified":"2026-07-13T05:56:45","modified_gmt":"2026-07-13T05:56:45","slug":"proximity-probe-setup","status":"publish","type":"calculator","link":"https:\/\/vibromera.eu\/lv\/calculators\/proximity-probe-setup\/","title":{"rendered":"Controlled Proximity-Probe Calibration Interpolator"},"content":{"rendered":"\n<script type=\"application\/ld+json\">{\"@context\":\"https:\/\/schema.org\",\"@type\":\"WebApplication\",\"name\":\"Controlled Proximity-Probe Calibration Interpolator\",\"description\":\"Interpolate gap or output voltage only between two controlled calibration-record points for one identified proximity-transducer system.\",\"url\":\"https:\/\/vibromera.eu\/calculators\/proximity-probe-setup\/\",\"applicationCategory\":\"EngineeringApplication\",\"operatingSystem\":\"Any\",\"offers\":{\"@type\":\"Offer\",\"price\":\"0\"},\"creator\":{\"@type\":\"Organization\",\"name\":\"Vibromera\",\"url\":\"https:\/\/vibromera.eu\/\"},\"dateModified\":\"2026-07-13\",\"inLanguage\":\"en\",\"isAccessibleForFree\":true}<\/script>\n<script type=\"application\/ld+json\">{\"@context\":\"https:\/\/schema.org\",\"@type\":\"FAQPage\",\"mainEntity\":[{\"@type\":\"Question\",\"name\":\"Does API 670 define one universal proximity-probe gap-voltage formula?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"This worksheet makes no such claim. It interpolates between two points from the controlled calibration record for one exact probe, extension cable, driver, target material and system configuration. Detailed API 670 requirements must be checked in the licensed current edition.\"}},{\"@type\":\"Question\",\"name\":\"Can I correct the result with a generic material factor?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"No. Target material, geometry and the complete transducer system affect the characteristic. Use calibration data for the actual approved system and target rather than a generic multiplier.\"}},{\"@type\":\"Question\",\"name\":\"Why are two calibration points required?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Two points define the local straight line including its offset. A sensitivity-only equation wrongly assumes a zero-volt intercept at zero gap. Two points still do not prove linearity, so the controlled record must authorize interpolation over the entered interval.\"}},{\"@type\":\"Question\",\"name\":\"Does an in-range result prove API compliance or a correct installation gap?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"No. In range means only inside the two entered calibration endpoints. It is not a compliance verdict, alarm setting, installation acceptance or substitute for the manufacturer and project procedures.\"}}]}<\/script>\n<script type=\"application\/ld+json\">{\"@context\":\"https:\/\/schema.org\",\"@type\":\"BreadcrumbList\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/vibromera.eu\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Calculators\",\"item\":\"https:\/\/vibromera.eu\/calculators\/\"},{\"@type\":\"ListItem\",\"position\":3,\"name\":\"Proximity-probe calibration interpolator\",\"item\":\"https:\/\/vibromera.eu\/calculators\/proximity-probe-setup\/\"}]}<\/script>\n<style>\n:root{--vc-surface:#fff;--vc-alt:#f8f6f2;--vc-ink:#1a1a1a;--vc-secondary:#5a5650;--vc-muted:#807b73;--vc-accent:#b84f22;--vc-accent-light:#fdf0ea;--vc-yellow:#825f00;--vc-yellow-light:#fff8dc;--vc-red:#9d2b24;--vc-red-light:#fff0ee;--vc-border:#d9d4cc;--vc-border-light:#e8e4dd;--vc-shadow:0 1px 3px rgba(26,26,26,.06),0 4px 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print{.vc-section-body,.vc-results{display:block!important}.vc-copy,.vc-chevron,.vc-actions{display:none}}\n<\/style>\n<div class=\"vc-calculator\">\n<header class=\"vc-header\"><p class=\"vc-eyebrow\">Calibration-record arithmetic \u00b7 interpolation only<\/p><h1 class=\"vc-title\">Controlled Proximity-Probe Calibration Interpolator<\/h1><p class=\"vc-subtitle\">Estimate gap from voltage, or voltage from gap, only between two approved calibration-record points for one identified probe, extension cable, driver, target and configuration.<\/p><div class=\"vc-badges\"><span class=\"vc-badge\">Two-point offset retained<\/span><span class=\"vc-badge\">No universal material factor<\/span><span class=\"vc-badge\">No API compliance verdict<\/span><\/div><\/header>\n<div class=\"vc-card\"><form class=\"vc-form\" id=\"vc-form\" novalidate><div class=\"vc-grid\">\n<div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-units\">Distance unit<\/label><select class=\"vc-select\" id=\"vc-units\"><option value=\"mm\">millimetre (mm)<\/option><option value=\"mil\">mil (0.001 in)<\/option><\/select><\/div>\n<div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-mode\">Solve for<\/label><select class=\"vc-select\" id=\"vc-mode\"><option value=\"distance-to-voltage\">Output voltage from gap<\/option><option value=\"voltage-to-distance\">Gap from output voltage<\/option><\/select><\/div>\n<div class=\"vc-field vc-wide\"><label class=\"vc-label\" for=\"vc-basis\">Controlled calibration record and exact system identity<\/label><input class=\"vc-input\" id=\"vc-basis\" autocomplete=\"off\" placeholder=\"Record\/revision; probe, extension cable, driver, total length, target material\/geometry and conditions\"><\/div>\n<div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-gap1\">Calibration gap x\u2081 <span class=\"vc-hint vc-distance-unit\">(mm)<\/span><\/label><input class=\"vc-input\" id=\"vc-gap1\" inputmode=\"decimal\" autocomplete=\"off\"><\/div>\n<div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-voltage1\">Output voltage V\u2081 <span class=\"vc-hint\">(V)<\/span><\/label><input class=\"vc-input\" id=\"vc-voltage1\" inputmode=\"decimal\" autocomplete=\"off\"><\/div>\n<div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-gap2\">Calibration gap x\u2082 <span class=\"vc-hint vc-distance-unit\">(mm)<\/span><\/label><input class=\"vc-input\" id=\"vc-gap2\" inputmode=\"decimal\" autocomplete=\"off\"><\/div>\n<div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-voltage2\">Output voltage V\u2082 <span class=\"vc-hint\">(V)<\/span><\/label><input class=\"vc-input\" id=\"vc-voltage2\" inputmode=\"decimal\" autocomplete=\"off\"><\/div>\n<div class=\"vc-field\"><label class=\"vc-label\" id=\"vc-query-label\" for=\"vc-query\">Query gap x <span class=\"vc-hint vc-distance-unit\">(mm)<\/span><\/label><input class=\"vc-input\" id=\"vc-query\" inputmode=\"decimal\" autocomplete=\"off\"><\/div>\n<label class=\"vc-check vc-wide\" for=\"vc-confirm\"><input id=\"vc-confirm\" type=\"checkbox\"><span>I confirm that both points belong to the same controlled system and target; the approved record declares straight-line interpolation valid over this interval and controls uncertainty\/linearity; the query is not extrapolated; and I will not treat this arithmetic as an API 670 verdict, alarm\/setpoint instruction or installation acceptance.<\/span><\/label>\n<div class=\"vc-actions vc-wide\"><button class=\"vc-calc-btn\" type=\"submit\">Interpolate within controlled span<\/button><\/div>\n<\/div><\/form><div class=\"vc-error\" id=\"vc-error\" role=\"alert\"><\/div>\n<div class=\"vc-results\" id=\"vc-results\" aria-live=\"polite\"><div class=\"vc-results-head\"><div><h2 class=\"vc-results-title\">Interpolation record<\/h2><div class=\"vc-results-basis\" id=\"vc-results-basis\">\u2014<\/div><\/div><button type=\"button\" class=\"vc-copy\" id=\"vc-copy\">Copy record<\/button><\/div><div class=\"vc-result-grid\">\n<div class=\"vc-result vc-primary\"><div class=\"vc-result-label\" id=\"vc-primary-label\">Interpolated output voltage<\/div><div class=\"vc-result-value\" id=\"vc-primary\">\u2014<\/div><\/div>\n<div class=\"vc-result\"><div class=\"vc-result-label\">Signed slope<\/div><div class=\"vc-result-value\" id=\"vc-slope\">\u2014<\/div><\/div>\n<div class=\"vc-result\"><div class=\"vc-result-label\">Line intercept at x = 0<\/div><div class=\"vc-result-value\" id=\"vc-intercept\">\u2014<\/div><\/div>\n<div class=\"vc-result\"><div class=\"vc-result-label\">Position through entered span<\/div><div class=\"vc-result-value\" id=\"vc-fraction\">\u2014<\/div><\/div>\n<\/div><div class=\"vc-warning\"><strong>\u201cInside span\u201d is not \u201ccompliant\u201d:<\/strong> the result is only mathematical interpolation between the entered endpoints. It does not establish transducer linearity, accuracy, installation gap, alarm limits, target suitability, interchangeability or conformity with API 670.<\/div><\/div><\/div>\n\n<section class=\"vc-section vc-open\"><button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"true\"><span class=\"vc-section-title\">Equations, units and applicability<\/span><span class=\"vc-chevron\">\u2304<\/span><\/button><div class=\"vc-section-body\"><div class=\"vc-section-inner\">\n<h3>Empirical two-point straight line<\/h3><div class=\"vc-formula\">S = (V\u2082 \u2212 V\u2081) \/ (x\u2082 \u2212 x\u2081)<br>b = V\u2081 \u2212 Sx\u2081<br>V(x) = Sx + b<br>x(V) = (V \u2212 b) \/ S<\/div>\n<p>x is physical probe-tip-to-target distance in millimetres, V is the recorded driver output in volts, S is the signed local slope in V\/mm, and b is the fitted voltage intercept. The inverse is allowed only when both gaps and both voltages are distinct. The worksheet rejects extrapolation.<\/p>\n<p>For mil input, the exact definition 1 mil = 0.0254 mm is used. Numerically, 1 V\/mm = 1 mV\/\u00b5m and 1 V\/mm = 25.4 mV\/mil. Negative-output systems can therefore have a negative signed slope; the sign comes from the entered record, not from a hard-coded sensor convention.<\/p>\n<div class=\"vc-danger\"><strong>Two points do not prove a linear range.<\/strong> They only define a line. Use this worksheet only when the controlled calibration or manufacturer record already establishes that interpolation is valid between those exact endpoints and gives the required uncertainty, environmental and configuration limits.<\/div>\n<\/div><\/div><\/section>\n<section class=\"vc-section\"><button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"false\"><span class=\"vc-section-title\">Confirmed defects removed from the former calculator<\/span><span class=\"vc-chevron\">\u2304<\/span><\/button><div class=\"vc-section-body\"><div class=\"vc-section-inner\">\n<div class=\"vc-table-wrap\"><table class=\"vc-table\"><thead><tr><th>Former claim or logic<\/th><th>Confirmed problem and correction<\/th><\/tr><\/thead><tbody>\n<tr><td>V = \u2212S \u00d7 gap with no intercept<\/td><td>This forces 0 V at zero gap and discards the system bias\/offset. The replacement fits both slope and intercept from two controlled points.<\/td><\/tr>\n<tr><td>\u201cCloser gap produces more negative voltage\u201d<\/td><td>The former wording contradicted the published example for a common negative-output system, where the output changes from approximately \u22121 V near 0.25 mm to \u221217 V near 2.3 mm. Direction is now taken from the record.<\/td><\/tr>\n<tr><td>Universal range by 5\/8\/12 mm probe diameter<\/td><td>Linear range is a complete-system\/manufacturer property, not a universal diameter-only table. All diameter presets and green in-range verdicts were removed.<\/td><\/tr>\n<tr><td>Generic factors for 4140, stainless steel, titanium, brass and aluminium<\/td><td>Target material and geometry affect the actual characteristic. Generic multipliers cannot replace a calibration for the selected probe, cable, driver, total length and target.<\/td><\/tr>\n<tr><td>\u201cAPI 670 standard \u221210 V target\u201d<\/td><td>A manufacturer may recommend a bias gap for a specific system, but that is not a universal API formula or setpoint. The replacement has no default, preset or compliance result.<\/td><\/tr>\n<tr><td>Partial parsing, automatic result and saved browser state<\/td><td>Blank explicit inputs, strict decimal parsing, submit-only calculation, controlled-record confirmation and safe text output replace implicit\/tampered state.<\/td><\/tr>\n<\/tbody><\/table><\/div>\n<\/div><\/div><\/section>\n<section class=\"vc-section\"><button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"false\"><span class=\"vc-section-title\">Official source boundaries and published numerical check<\/span><span class=\"vc-chevron\">\u2304<\/span><\/button><div class=\"vc-section-body\"><div class=\"vc-section-inner\">\n<h3>Manufacturer example is system-specific<\/h3><p>The official <a href=\"https:\/\/dam.bakerhughes.com\/m\/23d2a1de24360b13\/original\/3300-XL-8mm-Proximity-Transducer-System-Datasheet-141194-pdf.pdf\" target=\"_blank\" rel=\"noopener\">Bently Nevada 3300 XL 8 mm datasheet, document 141194 Rev. AM<\/a> describes one system made from its probe, extension cable and Proximitor Sensor. Its stated baseline conditions include an AISI 4140 target, \u221224 Vdc supply, 10 k\u03a9 load and defined temperatures. For that system it publishes an approximate 0.25\u20132.3 mm (10\u201390 mil) linear range corresponding to approximately \u22121 to \u221217 Vdc, recommends approximately \u22129 Vdc at 1.27 mm (50 mil) for radial vibration, and specifies a nominal 7.87 V\/mm (200 mV\/mil) incremental scale factor with configuration\/temperature tolerances.<\/p>\n<p>Using only the two approximate published envelope endpoints as a numerical software test, their midpoint x = 1.275 mm interpolates to \u22129 V and the inverse calculation returns 1.275 mm. This is a consistency test of the interpolation and the source\u2019s rounded example\u2014not a downloadable preset, a replacement for the actual calibration curve, or an acceptance tolerance.<\/p>\n<p>The same datasheet states that its default calibration is for AISI 4140 steel and that calibration for other target materials is available on request. Its performance statements are conditional on the identified components\/configuration; they do not support generic material multipliers.<\/p>\n<h3>API 670 and ISO 13373<\/h3><p>The official <a href=\"https:\/\/www.api.org\/products-and-services\/standards\/standards-plan\" target=\"_blank\" rel=\"noopener\">API Standards Plan<\/a> lists API Standard 670, <em>Machinery Protection Systems<\/em>, Edition 6, dated 7 July 2025. Detailed requirements are licensed and remain <strong>NEEDS_LICENSED_SOURCE<\/strong> here. This page therefore does not invent an API clause, universal bias voltage, linear range, accuracy limit or compliance verdict.<\/p>\n<p>The official <a href=\"https:\/\/www.iso.org\/standard\/21831.html\" target=\"_blank\" rel=\"noopener\">ISO 13373-1:2002<\/a> page identifies Edition 1 as published and confirmed in 2024. Its scope gives general vibration-condition-monitoring guidance including measurement methods, parameters and transducer selection\/location\/attachment. It is not cited as a universal proximity-probe gap-voltage transfer table.<\/p>\n<p>Sources and lifecycle checked 13 July 2026. Manufacturer limits apply only to the cited product\/configuration; project requirements, the current licensed API edition and the actual controlled calibration record govern.<\/p>\n<\/div><\/div><\/section>\n<section class=\"vc-section\"><button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"false\"><span class=\"vc-section-title\">Frequently asked questions<\/span><span class=\"vc-chevron\">\u2304<\/span><\/button><div class=\"vc-section-body\"><div class=\"vc-section-inner\">\n<div class=\"vc-faq\"><button type=\"button\">Can I enter nominal sensitivity and one gap?<\/button><div>No. A sensitivity-only equation omits the voltage offset. Enter two controlled point pairs from the same approved record.<\/div><\/div>\n<div class=\"vc-faq\"><button type=\"button\">May I use points from different probes or target materials?<\/button><div>No. Both points must describe the same complete probe, extension cable, driver, total length, target material\/geometry and applicable conditions.<\/div><\/div>\n<div class=\"vc-faq\"><button type=\"button\">What if my query lies outside the two points?<\/button><div>The worksheet rejects it. Extrapolation outside the controlled span can hide nonlinearity or saturation and requires an appropriate manufacturer\/calibration basis.<\/div><\/div>\n<div class=\"vc-faq\"><button type=\"button\">Does the result define alarm or shutdown settings?<\/button><div>No. It is a signal-distance interpolation only. Protection setpoints and voting\/trip logic require the applicable machinery-protection design and approved procedures.<\/div><\/div>\n<\/div><\/div><\/section>\n<section class=\"vc-section\"><button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"false\"><span class=\"vc-section-title\">Related engineering pages<\/span><span class=\"vc-chevron\">\u2304<\/span><\/button><div class=\"vc-section-body\"><div class=\"vc-section-inner\"><div class=\"vc-related\"><a href=\"\/calculators\/shaft-vibration-iso7919\/\">Shaft-vibration standard scope<\/a><a href=\"\/calculators\/vibration-unit-converter\/\">Vibration unit conversion<\/a><a href=\"\/glossary\/proximity-probe\/\">Proximity-probe glossary<\/a><\/div><\/div><\/div><\/section>\n<footer class=\"vc-footer\">Controlled-record interpolation only; the approved calibration, manufacturer limits and protection-system specification govern. \u00b7 <a href=\"\/calculators\/engineering-calculators\/\">All calculators<\/a><\/footer>\n<\/div>\n<script>\n(function(){\n\"use strict\";\nvar MIL_TO_MM=0.0254;\nfunction byId(id){return document.getElementById(id)}\nfunction parseNumber(text){var s=String(text).trim();if(!s||s.indexOf('.')>=0&&s.indexOf(',')>=0||!\/^[-+]?(?:\\d+(?:[.,]\\d*)?|[.,]\\d+)(?:[eE][-+]?\\d+)?$\/.test(s))return null;var n=Number(s.replace(',','.'));return Number.isFinite(n)?n:null}\nfunction toMm(value,units){if(!Number.isFinite(value))throw new Error('Distance must be finite.');if(units==='mm')return value;if(units==='mil')return value*MIL_TO_MM;throw new Error('Choose a supported distance unit.')}\nfunction fromMm(value,units){if(!Number.isFinite(value))throw new Error('Distance must be finite.');if(units==='mm')return value;if(units==='mil')return value\/MIL_TO_MM;throw new Error('Choose a supported distance unit.')}\nfunction proximityInterpolationModel(x){if(!x||![x.gap1Mm,x.voltage1,x.gap2Mm,x.voltage2,x.query].every(Number.isFinite))throw new Error('Every numeric input must be finite.');if(x.gap1Mm<0||x.gap2Mm<0)throw new Error('Calibration gaps must be zero or greater.');if(x.gap1Mm===x.gap2Mm)throw new Error('Calibration gaps must be distinct.');if(x.voltage1===x.voltage2)throw new Error('Calibration voltages must be distinct for an invertible relation.');var slope=(x.voltage2-x.voltage1)\/(x.gap2Mm-x.gap1Mm),intercept=x.voltage1-slope*x.gap1Mm,gapMin=Math.min(x.gap1Mm,x.gap2Mm),gapMax=Math.max(x.gap1Mm,x.gap2Mm),voltageMin=Math.min(x.voltage1,x.voltage2),voltageMax=Math.max(x.voltage1,x.voltage2),gapMm,outputVoltage,fraction;if(!Number.isFinite(slope)||slope===0||!Number.isFinite(intercept))throw new Error('The entered points do not define a finite invertible line.');if(x.mode==='distance-to-voltage'){if(x.query<0)throw new Error('Query gap must be zero or greater.');if(x.query<gapMin||x.query>gapMax)throw new Error('Query gap is outside the controlled calibration span; extrapolation is not allowed.');gapMm=x.query;outputVoltage=slope*gapMm+intercept;fraction=(gapMm-x.gap1Mm)\/(x.gap2Mm-x.gap1Mm)}else if(x.mode==='voltage-to-distance'){if(x.query<voltageMin||x.query>voltageMax)throw new Error('Query voltage is outside the controlled calibration span; extrapolation is not allowed.');outputVoltage=x.query;gapMm=(outputVoltage-intercept)\/slope;fraction=(gapMm-x.gap1Mm)\/(x.gap2Mm-x.gap1Mm)}else throw new Error('Choose a supported solve mode.');if(![gapMm,outputVoltage,fraction].every(Number.isFinite))throw new Error('A result is outside the finite numeric range.');return{slopeVPerMm:slope,interceptV:intercept,gapMm:gapMm,outputVoltage:outputVoltage,fraction:fraction,gapMinMm:gapMin,gapMaxMm:gapMax,voltageMin:voltageMin,voltageMax:voltageMax}}\nwindow.vbmProximityInterpolationModel=proximityInterpolationModel;window.vbmProximityParse=parseNumber;window.vbmProximityToMm=toMm;window.vbmProximityFromMm=fromMm;window.vbmProximityConstants={MIL_TO_MM:MIL_TO_MM};\nfunction fmt(n){if(n===0||Object.is(n,-0))return'0';var a=Math.abs(n),s;if(a>=1e9||a<1e-7)s=n.toExponential(9);else s=n.toPrecision(10);return s.replace(\/(\\.\\d*?[1-9])0+(e|$)\/,'$1$2').replace(\/\\.0+(e|$)\/,'$1').replace('e+','e')}\nfunction fail(message){byId('vc-error').textContent=message;byId('vc-error').classList.add('vc-show');byId('vc-results').classList.remove('vc-visible')}\nfunction hideOutput(){byId('vc-error').classList.remove('vc-show');byId('vc-results').classList.remove('vc-visible')}\nfunction unitText(){return byId('vc-units').value==='mm'?'mm':'mil'}\nfunction updateLabels(){var unit=unitText(),inverse=byId('vc-mode').value==='voltage-to-distance';document.querySelectorAll('.vc-distance-unit').forEach(function(node){node.textContent='('+unit+')'});byId('vc-query-label').textContent=inverse?'Query output voltage (V)':'Query gap x ('+unit+')';byId('vc-primary-label').textContent=inverse?'Interpolated gap':'Interpolated output voltage'}\nfunction clearNumbers(){['vc-gap1','vc-voltage1','vc-gap2','vc-voltage2','vc-query'].forEach(function(id){byId(id).value=''});byId('vc-confirm').checked=false;hideOutput()}\nfunction calculate(){var g1=parseNumber(byId('vc-gap1').value),v1=parseNumber(byId('vc-voltage1').value),g2=parseNumber(byId('vc-gap2').value),v2=parseNumber(byId('vc-voltage2').value),q=parseNumber(byId('vc-query').value),units=byId('vc-units').value,mode=byId('vc-mode').value,basis=byId('vc-basis').value.trim();if([g1,v1,g2,v2,q].some(function(n){return n===null}))return fail('Enter complete finite numbers. 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