What are the technical requirements for connecting a high-temperature smoke exhaust fan to ductwork?

For long-distance smoke exhaust systems, once the fan has been securely installed, it must be connected to the ductwork, commonly known as the flue. During smoke extraction, smoke is conveyed through the high-temperature smoke exhaust fan and ductwork to the designated location. This is a form of centralized smoke extraction.

The primary requirement for connecting a high-temperature smoke exhaust fan to ductwork is airtightness; there must be no air leakage. Any leakage will affect the fan’s smoke extraction capacity. The ductwork for high-temperature smoke exhaust fans is made of galvanized steel sheet. The insulation material must be a non-combustible type approved by the relevant local authorities. Duct seams must be tightly joined and uniform in width, with no holes, partially closed seams, or other defects.

The surface irregularities of the high-temperature smoke exhaust fan ductwork must not exceed 5 mm. The connection between the ductwork and flange must be secure, and the flanged edges must be even. A flexible connector is used between the ductwork and the high-temperature smoke exhaust fan to reduce vibration noise (decibels (dB)) during operation. A three-proof fabric can be used; it is corrosion-resistant, flame-retardant, and resistant to high temperatures.

Technical requirements for connecting a high-temperature smoke exhaust fan to ductwork specify that the flexible connector must extend 20 mm beyond the connection points at both the fan and the ductwork. It must then be secured with a metal clamp. The clamp must not be too loose, as this can cause air leakage or the connector to come off. It must not be too tight either: vibration from the high-temperature smoke exhaust fan could cause the clamp to break, resulting in the ductwork falling off.

Connection points between the high-temperature smoke exhaust fan and ductwork are also important locations for regular inspection and maintenance of the smoke exhaust system. Check for looseness to prevent smoke leakage, which can reduce the fan’s smoke extraction capacity and affect its normal operation.