1. Pibell Sgwâr (Tiwb Sgwâr)
Fformiwla:
[(Hyd + Lled) × 2 / 3.14 - Trwch Wal] × Trwch Wal × 0.02466 × Hyd × Nifer
Enghraifft:
Ar gyfer 40 × 40 × 1.2 mm (hyd 6m, 1000 pcs):
[(40 + 40) × 2 / 3.14 - 1.2] × 1.2 × 0.02466 × 6 × 1000
2. Pibell Rownd (Tiwb Crwn)
Fformiwla:
[(Diamedr Allanol) - Trwch Wal] × Trwch Wal × 0.02466 × Hyd × Nifer
Enghraifft:
Ar gyfer 2 fodfedd (OD 59mm) × 1.2 mm (hyd 6m, 1000 pcs):
(59 - 1.2) × 1.2 × 0.02466 × 6 × 1000
3. Pibell Hirgrwn (Tiwb Hirgrwn)
Fformiwla:
[(Hyd + Lled) × 2 - 24] / 3.14 - Trwch Wal × Trwch Wal × 0.02466 × Hyd × Nifer
Enghraifft:
Am 30 × 60 × 1.2 mm (hyd 6m, 1000 pcs):
[(30 + 60) × 2 - 24] / 3.14 - 1.2 × 1.2 × 0.02466 × 6 × 1000
