Controlled-source comparison · relative radial shaft vibration

Controlled Relative Shaft-Vibration Boundary Worksheet

Compare one documented vibration magnitude with three ordered boundaries copied from the exact applicable controlled standard, OEM specification or alarm philosophy—without inventing ISO zones or speed curves.

µm and milSigned boundary marginsNo embedded ISO limits

No automatic ISO zone or action verdict. The ISO 7919-1:1996 general document is withdrawn and was revised by ISO 20816-1:2016. Machine-specific parts, amendments, measurement quantities, locations and operating conditions are not interchangeable. This worksheet performs only unit conversion, ordering and subtraction using boundaries that you document from a controlled source.

Measured value and controlled boundaries

Reported relative radial shaft-vibration magnitudeNon-negative plain decimal; point or comma.

Shared displacement unitThe measured value and all three boundaries must use this same unit.

Boundary 1 (lowest)

Boundary 2

Boundary 3 (highest)

Boundaries must be non-negative and strictly increasing. They are not supplied by this website. At exact equality the worksheet reports the boundary explicitly and does not assign either adjacent band.

Project / machine train

Rotor / bearing / measurement plane

Machine type / power / bearing / shaft orientation

Speed / load / operating state

Probe / channel / calibration record

Signal processing / bandwidth / filtering

Exact measurement quantity and value convention

Controlled standard / OEM document / edition / part

Amendments / corrigenda / document status

Clause / table / figure / page for boundaries

Applicability / exclusions check record

Uncertainty / repeatability record

Controlled decision rule / alarm logic reference

Prepared / reviewed by

Record date

Notes and exclusions Optional: transient state, probe orientation, shaft surface, electrical/mechanical runout, baseline/change criteria

The reported value and all boundaries use the same measurement quantity, value convention, bandwidth, unit and measurement location required by the controlled source. The exact machine-specific part, edition, amendments, scope, power, speed, bearing type, shaft orientation and operating condition were checked. Any required interpolation, corrections, electrical/mechanical runout treatment and baseline/change criteria were applied outside this worksheet according to the controlled method. I understand that position relative to entered boundaries is not by itself an ISO conformance, alarm, trip or shutdown decision.

Arithmetic comparison

Position relative to entered boundaries

—

Measured magnitude

—

Normalized boundaries 1 / 2 / 3

—

Signed margin to Boundary 1

—

Signed margin to Boundary 2

—

Signed margin to Boundary 3

—

Equations and interpretation

1 mil = 25.4 µm exactly
signed margin to boundary i = Bᵢ − M

M is the documented measured magnitude and Bᵢ is an entered controlled boundary. A positive margin means M is below that boundary; zero means equality; a negative margin means M is above it. These are subtraction and exact unit conversion, not ISO evaluation formulas.

The worksheet reports seven mutually exclusive positions: below B1; exactly B1; between B1 and B2; exactly B2; between B2 and B3; exactly B3; or above B3. Exact equality is deliberately not assigned to either neighbouring band because the boundary convention and decision rule must come from the controlled source.

Model boundary and removed unsafe logic

No invented speed curves. The former page generated limits from hard-coded functions such as 0.9√n, 1.8√n and 3.1√n with arbitrary clamps. No verified ISO clause or table supported those functions, so all generated A/B/C/D thresholds were removed.
No universal 50/100/170 or 80/160/260 table. Those values were applied across unrelated machine classes and then presented as simplified ISO 7919 limits. Exact values must come from the correct current part and controlled source.
ISO 7919-1 is withdrawn. ISO 7919-1:1996 was withdrawn in 2016 and revised by ISO 20816-1:2016. Machine-specific ISO 7919-2, -3, -4 and -5 documents were also replaced by corresponding ISO 20816 parts.
Parts are not interchangeable. For example, ISO 20816-2 has a greater-than-40 MW, fluid-film-bearing and discrete-speed scope; ISO 20816-4 covers certain gas turbines above 3 MW; ISO 20816-5 covers specified hydraulic plant sets and varies criteria by turbine type, shaft orientation and bearing location.
Quantity and signal processing matter. Relative versus absolute, rotating versus non-rotating part, radial versus axial, displacement convention, broadband bandwidth, measurement plane, operating state and runout treatment must match the source.
No orbit-shape diagnosis. A single scalar cannot establish an orbit or diagnose unbalance, misalignment or rub. Orthogonal time-synchronous probe signals and appropriate analysis are required.
No generic action advice. “No action,” “monitor,” “plan maintenance” and “immediate shutdown” were removed. Alarm/trip settings require the controlled standard/OEM philosophy, machine history, protection design and engineering authority.
No guessed values. Exact numerical criteria, interpolation, boundary ownership and decision rules remain NEEDS_LICENSED_SOURCE unless a controlled document is supplied.

Current standard traceability

Document	Verified public status/scope	Use here
ISO 7919-1:1996	Edition 2; withdrawn; revised by ISO 20816-1:2016	Historical warning only; no limits used
ISO 20816-1:2016	Edition 1; published but to be revised; covers general measurement/evaluation including absolute and relative radial shaft vibration; excludes axial shaft vibration and torsional vibration	Scope/status only; no numerical criteria copied
ISO/FDIS 20816-1	Edition 2 final draft, stage 50.00 in 2026; under development	Not treated as a published normative replacement
ISO 20816-2:2017 + Amd 1:2024	Land-based gas/steam turbines and generators above 40 MW, fluid-film bearings, rated 1500/1800/3000/3600 r/min; published and confirmed	Exact machine scope and amendment must be checked
ISO 20816-3:2022	Industrial machinery above 15 kW and 120–30000 r/min; published but to be revised by ISO/FDIS 20816-3, stage 50.00 in 2026	Scope/status only; current controlled edition required
ISO 20816-4:2018	Certain land-based gas turbines above 3 MW, 3000–30000 r/min, with fluid-film bearings; published and confirmed	Scope/status only
ISO 20816-5:2018	Specified hydraulic generating/pump-storage sets, typically 60–1000 r/min, oil-lubricated shell/pad bearings; criteria depend on turbine type, shaft orientation and bearing location; confirmed 2024	Scope/status only
ISO 10817-1:1998	Rotating-shaft vibration measuring systems; relative and absolute sensing of radial vibration; published and confirmed 2021	Measurement-system scope only
NIST SP 811, Appendix B.8	1 inch = 25.4 mm exactly	Exact mil/µm conversion

Accessed: 15 July 2026. Official public cards establish only the displayed status and scope. They do not establish the three entered boundaries, interpolation, equality convention or decision rule. Worksheet URL: https://vibromera.eu/calculators/shaft-vibration-iso7919/

Arithmetic reference example

For M = 15 µm and entered boundaries B1 = 10 µm, B2 = 20 µm and B3 = 30 µm, the position is between B1 and B2. Signed margins Bᵢ − M are −5 µm, +5 µm and +15 µm. These arbitrary numbers verify subtraction only; they are not ISO criteria or an operating recommendation.

Questions

Why are ISO zone values no longer built in?

The previous values and square-root speed functions could not be tied to a verified current clause or table and mixed incompatible machine scopes. A controlled machine-specific part or OEM document is required before any numerical comparison.

Does “below Boundary 1” mean acceptable?

Not automatically. It means only that the entered measured number is smaller than the entered Boundary 1 number. Acceptance, alarms and trips also depend on the correct quantity, scope, operating state, change criteria, uncertainty and controlled decision rule.

Why is equality reported separately?

Assigning an exact boundary to the lower or upper band is a decision-rule detail. The worksheet does not guess it; consult the exact controlled clause or OEM alarm philosophy.

Can one probe magnitude diagnose an orbit?

No. An orbit requires two appropriately oriented, time-synchronous relative-displacement signals and validated processing. Orbit shape alone also does not prove a unique fault cause.