Definition & axiom
⚠ Conflicts with the ISO 15926-4 primary definition
Label (EN)
sight glass
Label (PT-BR)
Definition (EN)
Definition (PT-BR)
Semi-formal axiom (Aristotelian)
Axiom type
LLM classification basis: function-based → ≡
The concept is consistently defined by its designed function across all sources: ISO 15926-4 states 'purpose is to enable seeing the internals' and CFIHOS defines it as 'intended for viewing'. The physical form (transparent glass) serves this function but is not the primary identity criterion — many transparent materials and configurations can realize visual inspection. The subtypes (BULL'S-EYE, OBLONG, ROUND) vary in shape/construction but share the same visual inspection function.
Validation status
Why primitive (necessary only)
Reviewer notes
FOL theory & disjointness
First-order logic theory (generated)
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Disjoint with
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Expert review
Axiomatization steps
1
Identity-Giving Function
✓ done
⚠ not anchored
VisualInspectionFunction → VisualInspectionProcess
▼
COPI-Core operation
⚠ Process parent
PlannedProcess reaches no COPI-Core operation, and no gap (out of scope / coverage gap) is recorded.
LLM rationale:
Visual inspection is the identity-giving function that distinguishes sight glasses from other instrumentation. The function encompasses all operational uses: level monitoring, flow observation, phase detection, and general process visualization. InstrumentationFunction is the appropriate parent as sight glasses are instrumentation devices that provide process information through visual means.
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Expert review
2
Genus Proximus
✓ done
Instrument · Assembly
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Genus (genus proximum)
Most specific superclass — may be a domain class like "Valve" or an IOF-Core root.
BFO/IOF-Core Root
bfo:Object branch
bfo:ObjectAggregate branch
bfo:ImmaterialEntity branch
LLM rationale:
Both source hierarchies classify sight glass under instrumentation categories: ISO 15926-4 relates subtypes to 'INSTRUMENTATION ITEM' and CFIHOS classifies under 'general instrument'. Sight glass is more specific than the generic 'Instrument' class but belongs to that category as it provides process information through visual indication. Assembly is the appropriate BFO root as sight glasses are causally unified artifacts with removable components (glass, frame, gaskets, mounting hardware) assembled into a single maintainable unit.
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Expert review
3
Differentia Specifica
✓ done
∃bearerOf.VisualInspectionFunction
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Conditions that distinguish
Sight Glass
from sibling classes under genus
Instrument.
Only what is not already entailed by the genus.
Differentia expression
Differentia (natural language)
LLM rationale:
The VisualInspectionFunction is the minimal differentia that distinguishes sight glass from other instruments under the same genus. Other instruments provide quantitative measurements or specific process parameter indication, while sight glass uniquely provides direct optical access for qualitative visual assessment.
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Expert review
4
Necessary Parts
✓ done
no necessary parts
▼
Consider part-whole relations beyond subsumption:
hasComponentPartAtAllTimes (universal, structurally essential)
· hasComponentPartAtSomeTime (contingent, optional component)
LLM rationale:
No component terms are available in the Known Component Terms list, and the source definitions do not explicitly name necessary parts beyond the general reference to transparent material. While sight glasses typically have glass/transparent elements, frames, gaskets, and mounting hardware, these specific components are not named in the provided sources and are not in the Known Component Terms list, so no parts can be formally specified.
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Expert review
5
Process Participation Signature ⟨I, O, T⟩
✓ done
PortionOfFluid → VisualIndication
▼
Inputs (I)
Outputs (O)
Transformation (T)
LLM rationale:
Sight glass enables visual observation by transmitting light through a transparent barrier, allowing operators to observe fluid characteristics without direct contact. The input is the contained fluid being observed, and the output is visual information about that fluid's state. This constitutes measurement transduction as it converts physical process states into observable information for human interpretation.
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Expert review
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Alternative labels
none
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Synonyms / alternative labels (comma-separated) — skos:altLabel
Language auto-detected on export (PT if the label contains accents, EN otherwise).
Properties as BFO qualities
no CFIHOS/DEXPI properties
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No CFIHOS/DEXPI properties found for this cluster.
Custom axioms
none
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Axioms not produced by the pipeline. Each is appended verbatim as an
rdfs:subClassOf restriction on Sight Glass.
Write the restriction block in Turtle syntax (without the leading
rdfs:subClassOf).
Example: [ owl:onProperty :hasPart ; owl:someValuesFrom :Wellhead ]
Cross-standard divergences
none detected yet
▼
Click "Detect divergences" to analyse cross-standard disagreements for this cluster.
Source Definitions (2)
SIGHT GLASS — ClassOfFunctionalObject
Definition text hidden (copyrighted standard) — sign in to view, or follow the source link above.
cfihos V2.0
sight glass — TagAndEquipmentClass
Definition text hidden (copyrighted standard) — sign in to view, or follow the source link above.
Provenance tiers (2)
Sources the pipeline cited while building this entry. Verbatim = the quote was copied word-for-word from that source; summary = paraphrased.
Linked competency questions
- open What is a sight glass?
- open Is sight glass the correct genus for level sight glass in the COPI ontology?
OWL/Turtle preview
Download .ttl
Numeric
COPI_* IRIs from copi-iri-map.tsv, with the readable name as a trailing comment. Names not yet in the map stay readable.
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ID 388 · claude-sonnet-4-20250514
Created 2026-05-04 18:27
Updated 2026-09-08 12:26
