Full-bore Flow

• Flow conditions under which the water (and any entrained air carried by the water) occupies the full cross section of the pipe.

• Flow of water in a pipe where theoretically 100% of the cross-section of the pipe bore is filled. In practical terms, full-bore flow is regarded as achieved at water content greater than 95% by volume.

Siphonic systems are designed on the principle of full bore flow which means have higher drainage capacity and velocity, no gradient requirement of piping and requires smaller in pipe diameter. Therefore, flexibility and easier coordination of piping with other building elements and makes siphonic system far more superior on roof drainage system.

References

1. BS 8490:2007 Guide to siphonic roof drainage system
2. ASPE Standard 45 Siphonic Roof Drainage