Key Technical Points for Fire Protection Pipeline Construction
Fire protection pipeline works are a key component of fire protection systems, and their construction quality directly affects the system's water supply and fire-extinguishing effectiveness. The core technical requirements for fire protection pipeline construction include: Regarding pipe material selection, when the working pressure of indoor hydrant system piping is not greater than 1.2MPa, hot-dip galvanized steel pipes or thickened hot-dip galvanized steel pipes may be used; when the working pressure is greater than 1.2MPa, seamless steel pipes shall be used; the distribution piping of automatic sprinkler systems shall use internally and externally hot-dip galvanized steel pipes (DN100 and above may use plastic-coated steel pipes), and the nominal pressure of the piping shall not be lower than 1.2MPa. Regarding the selection of pipe connection methods, pipes DN50 and below may use threaded connections (after thread machining, burrs shall be removed and sealing shall be done with hemp thread/PTFE tape); DN65-DN100 may use clamp (groove) connections (the clamp material shall be ductile iron or cast steel, and the sealing ring material shall be EPDM); above DN100, flange connections or welding should preferably be used (after welding, internal and external surfaces shall undergo anti-corrosion treatment). Regarding pipe support installation, in accordance with the requirements of GB 50242-2002, the spacing of supports for horizontally installed steel pipes is: DN15 not exceeding 2.5m, DN20 not exceeding 3.0m, DN25 not exceeding 3.5m, DN32 not exceeding 4.0m, DN40 not exceeding 4.5m, DN50 not exceeding 5.0m, DN70 not exceeding 6.0m, DN80 not exceeding 6.0m, DN100 not exceeding 7.5m. Pipe supports shall be fixed to structural beams or floor slabs and shall not be fixed to lightweight partition walls or ceiling keels. Firestop sealing where pipes penetrate fire compartments, fire walls, and floor slabs is a key acceptance item; non-combustible materials (firestop sealant + firestop putty) shall be used for tight sealing, and the sealing thickness should not be less than 200mm. The gap between the pipe and the sleeve shall be filled compactly with firestop sealant. When pipes penetrate fire compartments, firestop collars shall be installed on both sides of the pipe. After pipeline installation is completed, a hydrostatic test shall be conducted (test pressure is 1.5 times the working pressure and not less than 1.4MPa, held for 30min without leakage) and pipeline flushing (flow velocity not less than 1.5m/s until the outlet water is clear).
Key Technical Points for Fire Protection Electrical Engineering Construction
Fire protection electrical engineering is the core support for automatic fire alarm and linkage control, and its construction quality directly affects the reliable operation of the fire protection system. The key technical requirements for fire protection electrical construction include: Regarding cable selection, the signal transmission lines of the automatic fire alarm system shall use flame-retardant twisted pair cables (RVS-2*1.5mm2 or RVVP-2*1.5mm2), fire linkage control lines shall use fire-resistant cables (NH-KVV series), fire power supply lines shall use fire-resistant power cables (NH-YJV series), and fire emergency lighting lines shall use fire-resistant conductors (NH-BV-2.5mm2). Regarding cable laying requirements, fire protection electrical cables shall be laid separately in dedicated cable trays or metal raceways (they shall not share cable trays with strong-current and weak-current cables). Metal raceways shall undergo fire protection treatment (apply fireproof coating or use fire-rated metal raceways). The fill ratio of cables in cable trays shall not exceed 40%. When cables are laid through conduits, the inner diameter of the conduit shall not be less than 1.5 times the outer diameter of the cable. Regarding fire protection of linkage control lines, direct control lines from the fire linkage controller to important fire protection equipment such as fire pumps and smoke exhaust fans shall use mineral-insulated cables (BTTZ or YTTW) or adopt fire protection measures such as laying in metal conduits with fireproof coating applied on the outside of the conduit. Regarding installation of fire power distribution boxes, fire power distribution boxes shall have obvious fire protection identification (red "Fire Protection" wording), the installation location shall facilitate operation, and the spare circuits in the distribution box shall be reserved at not less than 20%. Regarding detector installation, smoke detectors shall be not less than 0.5m from beam edges, not less than 1.5m from air-conditioning supply outlets, and not less than 0.5m from walls. The horizontal distance from detectors to broadcast speakers shall not be less than 0.1m. Manual alarm call points shall be installed at a height of 1.3-1.5m above the ground and shall have obvious "Press to Alarm" identification. The installation spacing of fire emergency lighting shall not exceed 20m, and the height above the ground shall not be less than 2.0m. The installation spacing of evacuation indicator lights shall not exceed 20m, and the height above the ground shall not be less than 0.5m.
Key Technical Points for Smoke Control and Exhaust System Construction
The construction quality of smoke control and exhaust systems directly affects the effective control of smoke during a fire and is a key inspection item in fire acceptance. The key technical requirements for the construction of smoke control and exhaust systems include: Regarding duct fabrication and installation, smoke control and exhaust ducts shall be made of galvanized steel sheet (thickness determined by duct size; for long side below 800 mm, steel sheet thickness not less than 0.75 mm; 800–1250 mm not less than 1.0 mm; 1250–2000 mm not less than 1.2 mm). Ducts shall be connected by flanges, and flange gaskets shall be made of non-combustible materials (asbestos rubber sheet or flame-retardant sealing strips). Where ducts penetrate walls or floor slabs, steel sleeves with thickness not less than 1.6 mm shall be provided, and the gap between the sleeve and duct shall be filled and sealed with non-combustible material. For the installation of fire dampers/smoke exhaust fire dampers, fire dampers shall be installed on both sides of ducts penetrating fire walls, deformation joints and fire compartment partition walls (distance from the wall shall not exceed 200 mm); smoke exhaust fire dampers shall be installed at the inlet of smoke exhaust fans (closing by fusion at 280°C); smoke exhaust fire dampers shall have electric closing function and manual reset function, and the installation orientation shall be correct to ensure the damper body closes automatically under gravity. For the installation of smoke exhaust outlets/supply outlets, smoke exhaust outlets shall be installed at the top or on the side wall within the smoke exhaust zone (distance from the ceiling not less than 800 mm); supply outlets shall be installed in smoke-proof stairwells and vestibules (one every 2–3 floors in stairwells, one per floor in vestibules); the connection between outlets and ducts shall be tight without air leakage. For the installation of smoke curtains, fixed smoke curtains shall be made of non-combustible materials (fire-resistant glass or steel fire-resistant panels), with installation height not less than 500 mm; after installation of electric smoke curtains, the descent speed and limit positions shall be commissioned, and no collision with other pipelines in the ceiling shall occur during descent. For fan installation, supply fans and smoke exhaust fans shall be installed in dedicated fan rooms or outdoors; flexible connections shall be used between fans and ducts (fire-resistant canvas length 150–200 mm); fan foundations shall be provided with vibration isolators; fan inlet and outlet openings shall be provided with protective screens. For system commissioning, after installation is completed, air volume testing shall be carried out (testing total air volume and air volume at each outlet), and the air volume deviation shall not exceed 15% of the design value; positive pressure testing shall also be carried out (stairwell residual pressure 25–30 Pa, vestibule residual pressure 25–30 Pa, corridor residual pressure 5–10 Pa).
Key points of fire protection coordination during decoration construction
Coordination between decoration construction and fire protection engineering is a key link in hotel fire acceptance. The selection of decoration materials, control of construction techniques, protection of and coordination with fire protection facilities directly affect the fire acceptance results. The key points of fire protection coordination during decoration construction include: Control of combustion performance of decoration materials — ceiling materials in hotel guest rooms shall be Class A (gypsum board, mineral wool board, etc.), wall materials not lower than Class B1 (flame-retardant wallpaper, flame-retardant fabrics, etc.), floor materials not lower than Class B1 (flame-retardant carpet, ceramic tile, etc.), and fabric materials such as curtains and drapes shall be Class B1 or reach Class B1 after flame-retardant treatment. Protection of fire protection facilities during decoration construction — during decoration construction, effective protection shall be provided for installed fire protection facilities (smoke detectors wrapped with protective covers to prevent dust ingress, sprinklers wrapped with plastic bags to prevent paint contamination); after decoration is completed, protective covers shall be removed and decoration material residue on the surface of fire protection facilities cleaned. Coordination between ceiling construction and fire protection facilities — sprinkler installation positions shall closely coordinate with ceiling design (concealed sprinkler decorative covers flush with the ceiling panel surface, pendant sprinkler deflectors 15–20 mm below the ceiling); installation holes shall be reserved for smoke detectors and broadcast speakers on the ceiling (hole positions shall be precise, with deviation not greater than 5 mm). Coordination between partition wall construction and fire protection systems — fire protection pipelines within partition walls shall be laid and accepted before the partition walls are closed; openings shall be reserved for fire hydrant cabinets installed on partition walls (opening size about 20 mm larger than the cabinet body for adjustment); the opening angle of fire hydrant cabinet doors shall not be less than 120 degrees. Coordination between fine decoration finishes and evacuation indicators — evacuation indicator lights shall not be obscured by fine decoration finishes (e.g., feature wall designs shall not block evacuation indicator lights); the installation spacing of evacuation indicator lights in evacuation corridors shall not exceed 20 m and they shall not be obscured by ceiling decorations or luminaires. Coordination for fire door installation — fire doors shall open in the evacuation direction; door closers shall be installed in place to ensure fire doors close automatically; fire door sealing strips shall be intact, and intumescent sealing strips shall be able to expand at high temperature to seal door gaps.