(Compliant with EN 837-1 / ASME B40.100 / OIML R109)
1. Scope and Reference Standards
This specification applies to visual inspection, incoming inspection, and in-service inspection of liquid-filled Bourdon tube pressure gauges and their supporting pressure gauge syphons (pigtail siphons/condensation siphons).
It is implemented in accordance with EN 837-1 (Europe), ASME B40.100 (North America), and OIML R109 (International Legal Metrology) to ensure compliance of product appearance, structure, marking, and accuracy for global industrial applications.
2. General Appearance and Structural Components Inspection
Visible Surface QualityVisible parts including the case, bezel, and window shall be free of apparent dents, deformations, scratches, corrosion, or coating peeling. Surface finish shall be uniform and smooth.Connection threads shall comply with ASME B1.20.1 / EN ISO 228-1, free of burrs, nicks, damaged threads, or sealing surface defects. Threads shall engage smoothly without defects affecting sealing or mechanical strength.
Filling Liquid Quality and LevelLiquid filling (glycerin/silicone oil) inside the case shall be clean, transparent, non-turbid, free of bubbles, impurities, or separation.Liquid level shall be strictly controlled at 0.25D to 0.3D above the center of the case (D = outside diameter of the gauge case), meeting damping and anti-vibration design requirements. No leakage or abnormal level due to evaporation is permitted.
Window and Reading ComponentsThe gauge window shall be colorless, transparent, and shatter-resistant, free of scratches, fogging, deformation, or defects impairing readability, in compliance with EN 837‑1 safety window requirements.The dial shall be flat and smooth with clear, durable markings, scales, numerals, and symbols, free of blurring, peeling, or misalignment for clear visibility at normal and long‑distance viewing.
3. Dial Marking and Labeling Inspection (International Standard Requirements)
The dial or case shall be permanently and legibly marked with:
Manufacturer name or registered trademark;
Product name: Liquid‑filled Pressure Gauge;
Legal units of measure (MPa/bar/psi, in accordance with SI units);
Pattern approval marking for measuring instruments (corresponding to MID/ANSI markings);
"-" (minus sign) for vacuum gauges;
Accuracy class: 1.0, 1.6, 2.5, 4.0 (consistent with OIML R109);
Serial number, manufacturing date, and standard compliance marking (EN 837‑1 / ASME B40.100).
4. Pointer and Scale Matching Inspection
The pointer tip shall cover 1/3 to 2/3 of the shortest graduation length.The width of the pointer tip shall not exceed the width of the graduation line.The pointer shall be straight, free of bending or deformation, and rotate smoothly without sticking.Clearance between the pointer and dial shall be uniform with no scraping, meeting ASME B40.100 pointer alignment and parallax requirements.
5. Zero Position Compliance Inspection
Gauges with a stop pin:Under no pressure or vacuum, the pointer shall rest against the stop pin.Zero offset shall not exceed the maximum permissible error for the accuracy class.
Gauges without a stop pin:Under no pressure or vacuum, the pointer shall lie within the zero mark.The width of the zero mark shall not exceed twice the maximum permissible error.The pointer shall not shift significantly after gently tapping the case, in compliance with OIML R109.
6. Visual Inspection of Pressure Gauge Syphon Pipes
As protective accessories, syphons shall also comply with international standards:
Material and Surface:Corrosion‑resistant metal, free of cracks, porosity, corrosion, or impact deformation. Welded and bent areas shall be smooth and defect‑free, with no mechanical damage affecting strength.
Structure and Dimensions:Uniform bend radius, no flattening or kinking, unobstructed bore. Threaded ends shall be intact with smooth sealing surfaces, compatible with gauge and equipment connections per DIN/ASME dimensions.
Installation Compliance:No leakage risk or excessive stress deformation. For high‑temperature media such as steam, the condensation loop shall be complete, meeting EN 837‑1 protective installation requirements.
7. Acceptance Criteria
All items meeting requirements of this standard and EN 837‑1, ASME B40.100, OIML R109 are deemed visually acceptable.Any non‑conformity results in rejection; the product shall not be placed into service.
