| Model | Length | Duct Width |
| M-1 | 12″ (305 mm) | 8″-14″ (203 – 355 mm) |
| M-1.5 | 18″ (457 mm) | 15″ – 20″ (381 – 508 mm) |
| M-2 | 24″ (610 mm) | 21″ – 30″ (533 – 762 mm) |
| M-3 | 36″ (914 mm) | 31″ – 42″ (787 – 1067 mm) |
| M-4 | 48″ (122 cm) | 43″ – 52″ (109 – 132 cm) |
| M-5 | 60″ (152 cm) | 53″ – 64″ (135 – 163 cm) |
| M-6 | 72″ (183 cm) | 65″ – 76″ (165 – 193 cm) |
| M-7 | 84″ (213 cm) | 77″ – 88″ (196 – 223 cm) |
| M-8 | 96″ (244 cm) | 89″ – 100″ (226 – 254 cm) |
| M-9 | 108″ (274 cm) | 101″ – 112″ (257 – 285 cm) |
| M-10 | 120″ (305 cm) | 113″ – 124″ (287 – 315 cm) |
| M-11 | 132″ (335 cm) | 125″ – 136″ (317 – 345 cm) |
| M-12 | 144″ (366 cm) | 137″ – 148″ (348 – 376 cm) |
Standard steam-jacketed manifolds should be used if you are using the 9000 and 1000 Series direct-steam-injection humidifiers, and vapor absorption distance is not critical, or is less than 36″ (91 cm).
The size and number of manifolds can be determined by face area of the duct or air handling unit, capacity, steam pressure, and required absorption distance. Armstrong Humid-A-ware humidification sizing and selection software will assist in these calculations.