4'' Enclosure Seal Diameter & Custom Flange Diameter

We need to make custom end caps for 4’’ BR enclosures.

For the 4’’ enclosure - I’ve seen that the endcap flange diameter (F) must be 103.95 ± 0.05mm. We have specified a f7 fit so 103.95 [-0.036, -0.071) which ensures it will always fit, though the minimum diameter is outside of the 0.05 boundary - we will need to revise this.

For the enclosure sealing surface diameter I’ve measured it and and it varies around 104.44mm, 104.51mm, 104.35mm.

This gives 104.44 - 103.95 = 0.49mm diameter clearance and 0.245mm radial clearance between the flange (piston) and housing (bore).

This this seems quite loose. Should we adjust our flange diameter or should we keep it to 103.95 ± 0.05mm to ensure correct fitment and pressure rating? (the caps fail deeper than enclosure).

What are the housing sealing flange diameter/specifications?

Thanks