What are the requirements for installing galvanized ventilation pipes in hotel dining area?

The installation of galvanized air duct in hotel dining area (especially kitchen) focuses on fire prevention, oil prevention, sealing, slope oil collection, stable support and hanger, and compliance acceptance. The following is a complete requirement for direct disclosure according to the system.

I. Material and wall thickness (kitchen fume/air supply must be separated)

Material: Hot-dip galvanized steel plate (GB/T 12771), galvanized layer ≥80g/㎡, without shedding and pinholes.

Kitchen oil fume (medium and high pressure, oily):

Long side ≤ 500mm: 1.0mm.

500～1000mm：1.2mm

＞1000mm：1.5mm

Fresh air/air supply in restaurant (low pressure):

≤450mm：0.6mm； 450～630mm：0.75mm； ＞630mm：1.0mm

It is forbidden to use 0.5mm thin material and ordinary iron sheet instead; It is forbidden to use a common flange for oil fume pipes (insufficient strength).

Second, the kitchen fume exhaust duct (the most important thing, fire prevention+oil prevention)

1. Slope and oil collection (preventing oil accumulation and backflow)

Horizontal section **≥2% slope **(1m drops by 20mm), and the slope direction is hood or oil collecting device.

Horizontal straight pipes are provided with inspection ports and oil collecting cups every 3 ~ 5m; The lowest point must be equipped with an oil collection sewage outlet.

Avoid "U-bend" and prevent oil pollution and water blockage.

2. Wind speed control (anti-oil hanging and anti-odor)

Main air duct: 10 ~ 15m/s; Branch pipe (smoke hood): 8 ~ 12m/s.

Wind speed < 8m/s is easy to hang oil; > 15m/s, with high noise and fast adhesion of oil dirt.

3. Flange and seal (smoke and odor prevention)

Angle flange: ∠ 40 ~ 50, bolt hole spacing ≤150mm, and bolts must be set at four corners.

Gasket: oil-resistant rubber pad for oil fume pipe/8501 flame retardant pad (3 ~ 5 mm); It is forbidden to use glass glue instead of gasket.

Fully apply oil-resistant sealant at the four corners of the flange; Tighten the bolts diagonally evenly, and add flat pad+spring pad.

4. Fire prevention and fire fighting (mandatory)

Passing through fire compartment, machine room and important room: 70℃ fire damper is set.

Where the kitchen oil fume exhaust branch pipe is connected to the vertical shaft, a fire damper of 150℃ (280℃ is for smoke exhaust only and cannot be mixed) is provided.

The distance between the air duct and combustible structure is ≥150mm, or it is insulated by non-combustible materials with a thickness of 50 mm..

The lampblack pipe is strictly prohibited to be shared with the fire smoke exhaust pipe; It is forbidden to cross sensitive areas such as guest rooms and lobbies.

Third, fresh air and air supply in restaurants/public areas

Slope: 0.5% ~ 1% slope drainage point to prevent condensation and dripping.

Flange seal: 8501 flame retardant pad, coated with weather-resistant adhesive; Add silencing soft joint (150～300mm) at the air supply outlet.

Dew-proof: The cold air pipe must be 25mm+centrifugal glass wool insulation+aluminum foil moisture-proof layer, and the interface is tightly sealed.

Four, the hanger and fixed (anti-fall, anti-vibration)

1. Spacing (kitchen encryption, anti-vibration loosening)

Horizontal (long side ≤ 400 mm): ≤ 3m; ＞400mm：≤2.5m； Kitchen oil fume pipe: ≤2m.

Vertical: ≤2.5m, and each riser has ≥2 fixed points; Each floor is provided with a bearing bracket.

Elbows, tees, fire dampers, and soft joints shall be provided with supports and hangers independently, and shall not be supported by supervisors.

2. Material and anticorrosion

Support and hanger: hot-dip galvanized angle steel/channel steel, screw rod M8 ~ M12, expansion bolt into the wall ≥ 70 mm..

Add 3mm rubber pad between the air duct and the bracket to prevent electrochemical corrosion and shock absorption.

Cut and joint rust removal+two anti-rust paints+topcoat to prevent rust.

3. Anti-sway and earthquake resistance

Horizontal pipe length > ＞20m: anti-sway supports, each system ≥1; Long-distance kitchen pipes: ≤10m.

Seismic fortification area: diagonal braces (45 ~ 60) are added and fixed with structural beams and columns.

Five, through the wall/floor and waterproof

Through-the-wall hole: the gap between the air duct and the wall is sealed with fireproof rock wool and waterproof mortar, and the outer side is sealed with weather-resistant sealant, and the water stop slope is low outside and high inside.

Through the floor: leave 50mm expansion joint, use fire sealant+incombustible material to block it, and set waterproof reverse edge.

Roof exit: add rain cap+bird net, and the air duct is higher than or equal to ≥1.5m above the roof to avoid rainwater backflow.

Vi. Anti-odor and hygiene

Keep negative pressure in the kitchen: make-up air volume is 80% ~ 90% of exhaust air volume to prevent oil fume from overflowing.

The fresh air inlet shall be far away from the oil fume outlet and garbage outlet, with a distance of ≥10m, so as to avoid inhaling peculiar smell.

Internal cleaning of air duct: no oil, dust and welding slag before installation; After the completion of the seal protection, to prevent debris from entering.

Seven, acceptance must check items

The material wall thickness meets the design, and the galvanized layer is intact.

The slope of the oil fume pipe is ≥2%, and the oil collection/inspection port is set correctly.

The flange seal has no smoke leakage, and the bolts are fully loaded and tightened diagonally.

The specifications (70℃/150℃) and position of the fire damper are correct, with independent supports and hangers.

Spacing between supports and hangers shall be in compliance, corrosion protection shall be in place, and sway/earthquake resistance shall be reliable.

Wall-penetrating/floor-blocking is tight in fire prevention and waterproof, and there is no hidden water seepage.

System trial operation: no air leakage, no odor, no abnormal vibration and noise.

Eight, common fatal mistakes (strictly prohibited)

Using 0.6mm thin material as kitchen oil fume pipe, it will deform and leak smoke in 1 ~ 2 years.

There is no slope or reverse slope in the horizontal section, and the oil and water are blocked and backflow.

Flange is not glued or glass glue is used instead of oil-resistant pad, which leaks smoke and smells.

The fire damper is installed at the wrong temperature (280℃ instead of 150℃) or there is no independent support.

The hanger is fixed on the ceiling keel/insulation layer and falls off later.