How to Choose a Vibration Sensor: 4 Stages — Measurand and Sensing Principle, Frequency and Range, Mounting and Cables, Environment and Wiring

For a vibration sensor, first decide the measurand and sensing principle (measuring shaft displacement and gap, or casing acceleration; using a proximity probe or an accelerometer); then look at frequency and range (how high a frequency must be measured, the sensitivity, and the amplitude limit); next, mounting and cables (how it is fixed, the type and length of cable, the matching parts of a probe system); after that, deal with environment and wiring (temperature, sealing, grounding, power, and hazardous areas). This article focuses on sensors that measure vibration on rotating machinery and equipment, including proximity probes and accelerometers; vibration motors, vibration analyzers, and seismic monitoring are outside its scope. The 4 stages:

• Stage ①｜Measurand and sensing principle: displacement, acceleration, proximity probes, piezoelectric, piezoresistive, and capacitive.

• Stage ②｜Frequency and range: frequency range, sensitivity, amplitude limit, the linear range of probes.

• Stage ③｜Mounting and cables: fixing method, cables, extension cables, probe systems.

• Stage ④｜Environment and wiring: temperature, sealing, grounding, power, hazardous areas.

This article starts from the point where you already know you need to measure a machine’s vibration. Each stage below covers: what to do, what the public sources say, and what Jiahon can help with; the data from each source and the basis are in the “Notes” at the end. This is the general case; individual cases still have to be judged on their own.

Figure 1: The four stages of choosing a vibration sensor. ① Measurand and sensing principle — shaft or casing: displacement or acceleration; proximity probe: measures the distance to the shaft; accelerometer: piezoelectric, piezoresistive, capacitive; at the end of this step: measurand and principle settled. ② Frequency and range — frequency range: the top end must be below resonance; sensitivity: choose high sensitivity for small signals; range: must not exceed the input range; at the end of this step: frequency and range settled. ③ Mounting and cables — fixing method: the firmer the attachment, the higher the frequency; cables: prone to problems; probe system: use matched parts; at the end of this step: mounting and cables settled. ④ Environment and wiring — temperature and sealing: check against site conditions; grounding and power: isolation and constant current; hazardous areas: per site conditions and maker data; at the end of this step: environment and wiring settled. (Illustration, not to scale.)

Stage ①: Measurand and sensing principle — first decide whether to measure shaft displacement or casing acceleration

What to do:

• First write down: what machine (turbine, pump, fan, compressor and their bearings), which point is measured, and whether what is to be measured is the motion of the shaft itself or the vibration of the casing.

• Proximity probe: a non-contact displacement sensor that measures the distance from the probe tip to the shaft, used to look at shaft vibration and gap.

• Accelerometer: mounted on the casing or bearing housing, it measures the acceleration of vibration; most vibration monitoring uses accelerometers.

• Velocity sensor: the sources say it is used for low- to mid-frequency measurement.

• Accelerometer principles: piezoelectric (including IEPE with built-in amplification), piezoresistive, and capacitive; to measure static acceleration, choose a type that can measure DC.

What the public sources say: An online encyclopedia entry says: vibration in industrial machinery is monitored with accelerometers, covering rotating equipment such as turbines, pumps, fans, compressors, and their bearings; piezoelectric types excel at high-frequency measurement, piezoresistive types tolerate shock (very high acceleration) better, and capacitive types use silicon micromachined sensing elements. Another online encyclopedia entry says: eddy current sensors are used to measure shaft displacement in rotating machinery. A software company’s community article (undated) says: the three main accelerometer technologies are piezoelectric (including IEPE), piezoresistive, and variable capacitance; piezoresistive types are DC-coupled and can measure static acceleration, such as one times gravity; IEPE cannot measure static acceleration. An instrument maker’s selection guide (undated; the page is reposted by a distributor) says: most vibration monitoring prefers accelerometers; velocity sensors are used at low to mid frequencies; displacement sensors are used to measure shaft motion and internal clearances, and proximity eddy current probes are used to sense shaft vibration. A measurement instrument company’s technical page (undated) says: an eddy current probe is a non-contact displacement sensor that measures the distance from the probe tip to the shaft (Notes, Table 1).

What Jiahon can help with:

• Vibration Displacement Probe: the product page says this is an eddy current (non-contact) probe that measures the radial vibration and axial position of a rotating shaft relative to the bearing housing, outputting a DC voltage of −1 to −17 V proportional to the gap, and must be used with a proximitor (signal conditioner). The product page lists probe diameters of 8 mm and 11 mm, threads of M10×1, 3/8-24 UNF, and 1/2-20 UNF, armored and unarmored versions, case lengths of 40 to 210 mm, and cables of 0.5 m and 1.0 m (the description table lists 7 models, and the options list 11 models). The linear range of the 8 mm probe is given as 2 mm (gap 0.25 to 2.3 mm), and that of the 11 mm probe as 4 mm; at the recommended gap of 1.27 mm the output is about −9 V. Sensitivity and frequency response are not stated on this page, so please inquire.

• Vibration Accelerometer: the product page says this is a piezoelectric ceramic accelerometer: sensitivity 100 mV/g (±5%), measurement range 80 g (peak), frequency response 10 Hz to 10 kHz (±3 dB), amplitude linearity ±1%; output is IEPE (2-wire constant current drive), top exit, 2-pin MIL connector; mounting is a 1/4-28 UNF screw base, and weight about 362 g.

Stage ②: Frequency and range — sensitivity times range must not exceed the input range

What to do:

• Frequency range: look at the flat usable bandwidth; the high-frequency end must be below the sensor’s resonant frequency.

• Sensitivity: choose high sensitivity for small signals, and low sensitivity for large shocks.

• Range: sensitivity multiplied by the measurement range gives the upper limit of the output voltage; if it exceeds the range of the acquisition system, the signal will be clipped.

• Amplitude limit: look at the linear range in the dynamic specifications; the environmental shock limit is only a survival figure, not a measurement range.

• Proximity probes: look at the linear range and standard sensitivity; at installation, set the initial gap near the middle of the range.

What the public sources say: An instrument maker’s selection guide (undated) says: most vibration in general industrial machinery is below 1000 Hz; the sensitivity of industrial accelerometers (in mV/g) is usually between 10 and 100; when a machine exceeds 10 g rms, a low-sensitivity one (10 mV/g) is better. A software company’s community article (undated) says: choose by the flat usable bandwidth, and the top of the frequency range should be well below the resonant peak; sensitivity multiplied by the measurement range equals the upper limit of the output voltage, and beyond it the signal is clipped by the fixed range of the data acquisition system. A 2009 selection article says: choose high sensitivity for small signals and low sensitivity for high-g shocks; use the linear range of the dynamic specifications, as the environmental shock limit is only a survival figure. An example from a 2022 eddy current probe system data sheet (maker; 8 mm range) is: linear range 0.5 to 8.5 mm, standard sensitivity 1.97 V per mm, frequency response DC to 5 kHz. A measurement instrument company’s technical page (undated) says: most probes have a range of 10 to 90 mil (the source unit), and at installation the initial gap should be as close as possible to 50 mil (Notes, Table 2).

What Jiahon can help with:

• Proximity Probe (reverse mount, metric thread): the product page says this is an 8 mm eddy current proximity probe, reverse mount (installed through the casing wall from the inside outward, with the probe tip facing the shaft center); linear range about 2 mm (80 mil), centered on a −10 V gap; sensitivity 7.87 V/mm (200 mV/mil, standard 4140 steel target); frequency response DC to 10 kHz (−3 dB); the page also says a 5 mm diameter is optional. The product page also says the default calibration target is 4140 steel, and if the shaft is not steel, a custom calibration must be ordered (it affects sensitivity and linearity); the total length of probe plus extension cable must not exceed the system’s distance limit (usually a 5 m system). The options offer only one model (1.0 m cable).

• Proximity Probe (reverse mount, inch thread): the product page says this page is also an 8 mm eddy current proximity probe, reverse mount; the difference from the previous page is the thread: this page is 3/8-24 UNF, the previous M10×1; the figures for linear range, sensitivity, and frequency response are the same on both pages. The options have 3 models (0.5 m and 1.0 m cables, with different certification suffixes), and a fluid-resistant cable is optional (preventing oil from leaking along the cable). The meaning of each segment of the model code is explained in a table on the page; when ordering, please give the full model of your existing probe.

Stage ③: Mounting and cables — fix it firmly, use the right cable, and match the system

What to do:

• Fixing: the firmer the attachment, the higher the frequency that can be measured; stud mounting gives better high-frequency response; use adhesive sparingly, as too much damps the vibration response.

• Weight: the accelerometer’s weight should not exceed ten percent of the weight of the object measured.

• Cables: the cable is usually the weak link of a measurement system; charge-mode types need low-noise cable, and IEPE can use ordinary cable; the longer the cable, the more noticeable the high-frequency attenuation.

• Proximity probe system: the probe, extension cable, and proximitor must be matched; the total cable length of the system must follow the maker’s data.

• Check: use the DC gap voltage from the proximitor output to confirm the probe is installed correctly and the cable length is not mismatched.

What the public sources say: A software company’s community article (undated) says: the firmer the attachment between accelerometer and object, the higher the frequency that can be measured; wax, quick-drying glue, magnetic bases, or studs can be used, and silicone grease can improve high frequencies; the cable is usually the weak link of the measurement system and fails more easily than the accelerometer; lengthening the cable increases resistance and capacitance, and long cables cause high-frequency attenuation; charge-mode types need low-noise cable. A 2017 maker contribution (published in an instrumentation magazine) says: stud mounting gives excellent high-frequency response; the less glue the better, as too much damps the vibration response; charge accelerometers need low-noise cable, while IEPE works with almost any cable. The 2009 selection article says: the accelerometer’s weight should not exceed 10% of the object measured. An example from a 2022 probe system data sheet (maker) is: the system consists of a calibrated probe, a possible extension cable, and a universal proximitor; total system cable length can be 5, 7, or 9 meters. A measurement instrument company’s technical page (undated) says: the proximitor outputs a DC gap voltage, and most monitoring system panels have a button to check it; if the cable length does not match, the actual output will differ from what is expected (Notes, Table 3).

What Jiahon can help with:

• Extension Cable: the product page says this is an interconnect cable of fixed length 20 feet (about 6.1 m), three-core shielded, 22 AWG, with a stainless steel armored outer jacket (described as resisting mechanical impact, oil, and chemical corrosion); one end is a 3-socket plug (to the proximitor) and the other end has terminal lugs. The page notes that the last two digits of the model are the length code, and the length should be chosen by the actual distance from sensor to proximitor plus a 10 to 15% margin, to keep the cable from being under tension. The product page describes what it pairs with in two ways (the title says eddy current probe system, the specification table says accelerometer or seismic / vibration sensor system), which is inconsistent, so please inquire to confirm which it connects to.

• Proximity Probe System (combined page for probe, extension cable, and proximitor): the product page says this is a combined page for the three components of an eddy current measurement system — proximity probe, extension cable, proximitor — with 10 options in total (2 probes, 5 extension cables, 3 proximitors). The page stresses that the three components must use the same system length (5 m or 9 m): when replacing any one changes the total length, the proximitor must also be changed to one for the matching system length, or the output sensitivity (V/mm) will shift and readings will be wrong; this is the same thing the source above says, “if the cable length does not match, the actual output will differ from what is expected.” The description table lists extension cable lengths of 4.0 to 8.5 m, and the proximitor’s frequency response is DC to 10 kHz. For how the options pair up, please inquire to confirm.

• Proximity Probe System for Small Machines: the product page says this is another series of eddy current probe system, designed for small machines with shaft diameters under 51 mm: total system length 6.0 m, 3/8-24 UNF thread, armored, miniature coaxial connector; linear range 0.635 to 6.35 mm, frequency response DC to 10 kHz, output sensitivity 7.87 V/mm; mounting on DIN rail or panel. The options offer only one model.

Stage ④: Environment and wiring — temperature, sealing, grounding, and power

What to do:

• Temperature: piezoelectric, IEPE, and capacitive (MEMS) types have different temperature ranges, as do probes and proximitors; check them against the site.

• Sealing: check whether the sensor is sealed against high humidity and moisture; temperature transients from hot air or oil splash may expand the case and cause false output.

• Grounding: the accelerometer case must be electrically isolated from ground, to avoid power-frequency noise from ground loops.

• Power: IEPE and other sensors with built-in amplification need a constant-current DC supply.

• Hazardous areas: where there are flammable gases or dusts, the sources mention intrinsically safe types; for actual requirements, follow the site conditions and the maker’s data.

• Calibration: the sources recommend periodic calibration, including a check of the transverse axis.

What the public sources say: A 2017 maker contribution says: piezoelectric types can be used up to 260 °C, IEPE is 125 °C as standard and 185 °C in a high-temperature version, and MEMS types have a limited temperature range; it recommends annual calibration and asks for the transverse axis to be checked during calibration. The 2009 selection article says: IEPE is used where the vibration range is known and temperatures are up to about 125 °C, and charge-mode types above 175 °C or when the upper acceleration limit is unknown. A software company’s community article (undated) says: IEPE is powered with a constant current of 4 mA; the accelerometer case must be electrically isolated from ground to avoid ground loops, which add 50 or 60 Hz spikes. An instrument maker’s selection guide (undated) says: most sensors with built-in amplification need a constant-current DC supply; temperature transients can expand a metal case and cause false output; that maker’s sensors are all sealed against high humidity and moisture; intrinsically safe sensors are, as the page puts it, incapable of ignition, and should be used where flammable gases or combustible dusts may be present. An example from the 2022 probe system data sheet (maker) is: proximitor operating temperature −30 to +90 °C, probe −30 to +180 °C (Notes, Table 4).

What Jiahon can help with:

• Vibration Accelerometer: the product page says this is an intrinsically safe type with a stainless steel case; the description lists hazardous area classification markings (one each for North America and Europe), and says it must be used with an intrinsic safety barrier installed on the safe-area side; it also mentions a high EMI/RFI shielding design and says magnetic mounting should be avoided (it lowers high-frequency response, consistent with the fixing methods in the sources above). This is the product page’s statement; whether it can be used in places with flammable gases or combustible dusts, and how to configure it, should follow the site’s hazardous area classification and the maker’s written data, confirmed by someone who knows explosion protection. The product page does not state operating temperature or protection rating, so please inquire.

• Vibration Displacement Probe: the product page states an operating temperature of −52 to +177 °C (cable up to +260 °C), a PPS probe tip, stainless steel case, and O-ring differential pressure seal; for outdoor or high shock and vibration environments, the page recommends choosing an armored model.

• Proximity Probe (reverse mount, metric thread): the product page states probe tip −40 to +177 °C, with the cable section of the high-temperature version up to +260 °C; explosion-proof certification depends on the model suffix. The inch-thread page (reverse mount) gives the same temperature figures, and the suffix explanation is on that page.

• Proximity Probe System for Small Machines: the product page states an operating temperature of 0 to +45 °C (with a high-temperature version extendable to +177 °C).

• Grounding and power conditions are mostly not stated on the product pages (only the accelerometer page states IEPE constant current drive); please inquire, and include the machine type, measurement point, temperature, whether there is a hazardous area, and the controller input.

When you need to match a type, please prepare six items first: whether you are measuring shaft displacement or casing acceleration, the frequency and amplitude range, the mounting position and fixing method, the cable length and system matching, the site temperature and environment, and the input of the controller or monitoring system. You are welcome to contact Jiahon.

Further reading: “Accelerometer vs. Eddy Current Displacement Probe“

Notes: sources and exceptions

The following is for those who need to verify; skipping it does not affect the method above. Where your equipment specifications, the sensor maker’s written data, or conditions of use differ from this article, they take precedence.

Sources for each stage

Table 1｜Measurand and sensing principle

Sources: 1, 2, 3, 6, 7

Table 2｜Frequency and range

Sources: 3, 4, 6, 7, 8

Table 3｜Mounting and cables

Sources: 3, 4, 5, 7, 8

Table 4｜Environment and wiring

Sources: 3, 4, 5, 6, 8

This is the general case; individual cases still have to be judged on their own.

Exceptions and limits

• What we saw and did not see: this article looked at two online encyclopedia entries (edited by many people), a software company’s community article (undated, no author), a 2009 selection article (republished by industry media), a 2017 instrument maker’s contribution (promoting its own products), a selection guide reposted by a laboratory equipment distributor (the content is a sensor maker’s material, undated), a measurement instrument company’s technical page (undated), and a 2022 maker data sheet for a probe system (a single model). We did not read the full text of any vibration measurement standard (the sources only mention the names of standards, and this article does not say “complies with such-and-such standard”); the sources give no selection details for velocity sensors, so the main text says only that they are used at low to mid frequencies; the sources do not explain the effect of target material on readings, so the main text does not discuss target material; we did not read the specification sheet of any Jiahon product.

• The figures are examples: 1000 Hz; 10 to 100 mV/g; 10 g rms; 0.5 to 8.5 mm, 1.97 V per mm, DC to 5 kHz; 10 to 90 mil, 50 mil; ten percent of weight; 5, 7, 9 meters; 260, 125, 185, 175 °C; 4 mA; −30 to +90 °C, −30 to +180 °C — these are each source’s examples, not selection thresholds; Source 5 is a maker’s contribution, and Source 8 is a data sheet for a single model; the unit of 10 to 90 mil in the source is mil (one thousandth of an inch), and the main text does not convert it.

• The sources do not say exactly the same thing: for IEPE temperature, Source 4 says up to about 125 °C and Source 5 says 125 °C standard and 185 °C for a high-temperature version; the two do not conflict and are listed side by side; Source 2 says only that eddy current sensors are used to measure shaft displacement, without giving range or frequency response, and those figures are taken from Sources 8 and 7.

• Single sources: piezoresistive types measuring static acceleration while IEPE cannot (Source 3); most vibration in general industrial machinery being below 1000 Hz, the sensitivity range, and the 10 g rms advice (Source 6); accelerometer weight not exceeding ten percent of the object (Source 4); probe system cable lengths of 5, 7, 9 meters (Source 8); gap voltage checks and initial gap (Source 7); annual calibration and transverse axis check (Source 5); the statement on intrinsic safety (Source 6) — this records only what the source says and is not to be taken as a basis for safety.

• Sources with a stake: Source 3 is a software company, Source 5 is an instrument maker’s contribution promoting its own products, Source 6 is a distributor reposting maker material, Source 7 is a measurement instrument company, Source 8 is a maker’s single-model data sheet, Sources 1 and 2 are an online encyclopedia edited by many people, and Source 4 is a 2009 industry media article; none is a standard itself or a third-party test report.

• The sources are in English: the Chinese version of this article is a translation.

• Hazardous areas: this article only relays what the sources and product pages say (intrinsically safe type, used with a safety barrier); it does not say “complies with such-and-such regulation” or “this makes it safe”; for places with flammable gases or combustible dusts, follow the site’s hazardous area classification and the maker’s written data for actual requirements, confirmed by someone who knows explosion protection.

• This article’s own synthesis: the main text does not use the “this article’s synthesis” label; each statement can be traced to the sources above.

• Scope: this article is a selection summary; vibration motors, vibration analyzers, and seismic monitoring are outside its scope; it also does not discuss model cross-references between makers, prices, or lead times.

• Equipment and products: the figures and statements in “What Jiahon can help with” were read from the text of the product pages on October 13, 2026; we did not look at product images or read any specification sheet, and they were not verified by this article; specifications are as on the product pages, and for anything the product page does not state, please inquire. This article does not cite the models, brands, claims of standard compliance, “interchangeable without calibration,” marketing wording, or descriptions of other products on the product pages. The product pages are inconsistent with one another in a few places, which this article records as they are without reconciling them: first, “reverse mount” for proximity probes is described on one page as installed through the casing wall from the inside outward, and on another page (the combined page for probe, extension cable, and proximitor) as the cable exiting from the rear of the probe; second, several pages say the probe, extension cable, and proximitor are interchangeable without calibration, while the combined page says they must use the same system length or the sensitivity will shift — this article did not verify how the two statements relate; third, the extension cable page’s title says eddy current probe system, while its specification table says accelerometer or seismic / vibration sensor system. Please inquire to confirm these.

This article is a compilation of the general case. It is not a restatement of the clauses of any standard, nor an endorsement of any maker, equipment maker, or service provider, and it does not mean your equipment and process will get the same results. Go by your equipment specifications, the sensor maker’s written data, and your own verification; this is the general case, and individual cases still have to be judged on their own.