EN 14850: Measurement of Contact Height for 25.4 mm Aerosol Containers

Standard Overview

EN 14850 defines the standardized measurement method for contact height on metal aerosol containers with a 25.4 mm aperture.

It does not define container geometry, but specifies how clinch-relevant geometry must be measured to ensure repeatability across filling lines and suppliers.

Scope and Applicability

• Tinplate containers according to EN 14847
• Aluminium containers according to EN 15006
• Valve cups according to EN 14848

The method applies exclusively to 25.4 mm aerosol systems.

Definition of Contact Height

Contact height (h) is defined as the distance between:

• The horizontal tangential plane of the aperture lip
• The centre of curvature of the clinching jaw extremity

• Di – Internal diameter of aperture = 25.4 mm
• t – Wall thickness of valve cup = 0.3 mm
• R – Radius of clinching jaws = 1.2 mm
• CD – Clinch diameter of jaws = 27.1 mm
• h – Contact height

Measurement Principle

The measurement reproduces the real clinching condition by simulating the geometry of the clinching jaws acting through the valve cup wall.

Key – Figure 2

• 1 – Point of hard contact between measuring radius and internal aperture profile
• 2 – Diameter of the clinching jaws (CD)

Instrument Geometry

To achieve equivalence with real clinching, the clinching jaws are replaced by a dedicated measuring instrument.

Key – Figure 3

• 1 – Contact height (h)
• 2 – Constant of the measuring instrument

Measurement Procedure

Equivalent Measuring Radius

The measuring radius r is defined as:

r = Rc + t

• Rc – Radius of curvature of clinching jaws = 1.2 mm
• t – Valve cup wall thickness = 0.3 mm

Resulting in:

r = 1.5 mm

Instrument Constant (0.35 mm)

The centre of the measuring radius is positioned at a fixed horizontal offset from the internal tangent of the aperture.

This constant is derived from:

R + t − (CD + 2t − Di) / 2 = 0.35 mm

Measurement Steps

1. Zero the instrument using the reference setting piece
2. Position the instrument to achieve hard contact
3. Measure contact height at three equidistant positions
4. Record mean, maximum, and minimum values

Why Contact Height Matters

Correct contact height supports:

• Consistent clinch geometry
• Uniform gasket compression
• Stable sealing performance

However, EN 14850 clearly states that contact height alone does not guarantee leak-tightness.

Relationship with Other Standards

• EN 14847 – Tinplate aperture dimensions
• EN 15006 – Aluminium aperture dimensions
• EN 14848 – Valve cups
• EN 15010 – Clinch-related tolerances
• FEA 216 – Clinching jaw bearing surfaces

FAQ – Engineering & QA