Orifice Bore: Diameter Ratio (β) 0.2-0.75, Taper ≤ 0.0005d

Q: What is the beta ratio in orifice bore design?

Beta ratio (β) is the ratio of bore diameter to pipe internal diameter (d/D). Critical for flow calculation accuracy, typically maintained between 0.2-0.75 per ISO 5167.

Q: How does bore edge condition affect measurement?

Sharp, square edges (≤0.0004d radius) ensure consistent vena contracta formation and predictable pressure drop. Worn or rounded edges cause flow coefficient drift and measurement errors up to 5%.

Component Specifications

Definition

The orifice bore is the precisely machined circular opening in an orifice plate, a primary element in differential pressure flow measurement systems. It creates a constriction in the fluid flow path, generating a measurable pressure drop that correlates to flow rate according to Bernoulli's principle and continuity equations. The bore's geometry, edge sharpness, and dimensional accuracy are critical for measurement precision.

Working Principle

Creates a controlled flow restriction, converting kinetic energy to pressure energy. The pressure differential across the bore (upstream vs. downstream) is measured and calculated using standardized equations (ISO 5167) to determine volumetric or mass flow rate.

Materials

Stainless steel (AISI 304/316), Hastelloy, Monel, carbon steel, or specialized alloys matching process fluid compatibility; hardness ≥150 HB; surface finish Ra ≤ 0.8 μm.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Taper	≤ 0.0005d
Thickness	1/8 to 1/2 plate thickness
Bore Diameter	0.25-12 inches (6-300 mm)
Concentricity	≤ 0.005D
Edge Sharpness	≤ 0.0004d radius
Diameter Ratio (β)	0.2-0.75

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards

ISO 5167, ASME MFC-3M, DIN 1952

Engineering Analysis

Risks & Mitigation

Erosion/corrosion altering bore geometry
Fouling/blockage affecting flow
Improper installation causing flow distortion
Thermal expansion mismatch

FMEA Triads

Trigger: Abrasive particle impingement
Failure: Bore diameter increase >0.5%, edge rounding
Mitigation: Hard-faced materials, upstream filtration, regular calibration

Trigger: Cavitation in high ΔP applications
Failure: Pitting erosion, noise/vibration
Mitigation: Limit ΔP to <0.25P1, multi-stage orifice plates

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

±0.05% of bore diameter for d≥50mm, ±0.1% for d<50mm per ISO 5167-2

Test Method

Optical comparator measurement, air gauge calibration, flow calibration against master meter

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

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Manufacturers of Orifice Bore

Manufacturer profiles associated with Orifice Bore.

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Frequently Asked Questions

What is the beta ratio in orifice bore design?

Beta ratio (β) is the ratio of bore diameter to pipe internal diameter (d/D). Critical for flow calculation accuracy, typically maintained between 0.2-0.75 per ISO 5167.

How does bore edge condition affect measurement?