Beijing DB11/T 2382-2024 general building services installation: quota item selection for cabinet (box-type) centrifugal fans - Table C.7.8-7 fan box items, discernment between the box-type and machinery-volume centrifugal fan scopes, and the treatment of supports, hangers and bottom bedding

Topic Positioning

Within the general building services installation works of Beijing DB11/T 2382-2024 "Consumption Standard for Construction Works": quota application knowledge for cabinet (box-type) centrifugal fans - installation item selection (including the discernment logic between box-type fans and the machinery-volume "centrifugal forced/induced draft fan" items), cost composition, and the pricing treatment of the accompanying supports, hangers and bottom bedding.

Core Conclusions

1. Installation item selection Fan box installation is priced under Table C.7.8-7 "fan box installation" (C7-1-104 to 115), banded by installation type and airflow and measured per unit. Clause 6.7.17 (original text): "The quantity of fan box installation shall be distinguished by installation type and airflow and computed as the number shown on the design drawings." Work content of the items (C7-1-113 as an example): "handling within the site, unboxing, checking, positioning, aligning and levelling, and trial running; installation of bottom bedding is not included." The consumption covers labour and plant only (lorries, electric winches, hoisting plant etc.); the fan itself is unpriced equipment, billed separately at preparation-period prices. Airflow band reference: two groups of 5000/10000/20000/30000/40000/50000/70000 and 5000/10000/20000/30000/100000, with labour and plant configuration differing between the groups.

2. Box-type vs centrifugal volume discernment

• Clause 6.1.35: "Installation of low- and medium-pressure centrifugal ventilators, dust-exhausting centrifugal ventilators, corrosion-resistant centrifugal ventilators, explosion-proof centrifugal ventilators, high-pressure centrifugal ventilators, boiler centrifugal ventilators, smoke-exhausting ventilators, multi-blade centrifugal ventilators, constant-temperature fan heaters, unit heaters, low-noise centrifugal ventilators, low-noise roof centrifugal ventilators, plastic fans and acid-resistant ceramic fans shall follow the centrifugal forced/induced draft fan installation items."
• Clause 6.1.37: "Ventilator installation in general industrial and civil building works shall follow the applicable items of the ventilation and air-conditioning works." -> Fan boxes in civil HVAC therefore use the dedicated fan box table of the ventilation and air-conditioning chapter (C.7), not the machinery-volume "centrifugal forced/induced draft fan" items. Practical test: equipment delivered in box form (factory inlet/outlet box panels) - use fan box installation; bare machine (fan plus base, no box) - centrifugal forced/induced draft fan scope under clause 6.1.35, with the volume decided by clause 6.1.37.

3. Three-step treatment of supports, hangers and bedding

1. Supplied with the equipment: clause 6.7.5 "the consumption for ventilation and air-conditioning equipment installation shall include installation of equipment supports or bottom bedding supplied with the equipment" - already included in the installation cost, with no further quota item or billed item, their value being carried in the equipment price.
2. Site fabrication: clause 6.7.24 "the quantity of equipment support fabrication and installation shall be distinguished by the weight of each support and computed as the weight shown on the design" - use Table C7.12-1 "equipment support fabrication and installation" (C7-1-172 to 174, banded by each support not over 20/40/60 kg, unit of measurement 10 kg); "the quantity of equipment bottom bedding installation shall be distinguished by material and computed as the weight shown on the design"; "the quantity of fan hanger fabrication and installation shall be distinguished by fan model and computed as the number shown on the design" - use Table C7.12-2 "mixed-flow (diagonal-flow) fan hanger fabrication and installation" (C7-1-175 to 177, sizes 5/7/8, per unit, including vibration-isolator installation, adjustable where the number of isolators differs from the design).
3. Axial fan hangers by analogy: note to C7-1-175 - when an axial fan is suspended, its support fabrication and installation follows the mixed-flow (diagonal-flow) fan hanger item, "all consumptions except the vibration isolators being multiplied by a coefficient of 0.9", a size 5 axial fan corresponding to size 5 mixed-flow, 6.3 and 7.1 to size 7, and 8, 9 and 10 to size 8. Additionally: where ventilation and air-conditioning equipment or materials are installed at a height above 6 m, the labour efficiency reduction caused by excess-height work follows clause 6.1.2 of the standard (clause 6.7.2).

Applicability Boundaries

• Applies to projects priced under DB11/T 2382-2024 in Beijing; other regions must check the local consumption standard / budget quota manuals.
• Discernment follows the delivery form of the equipment: box delivery - fan box table; bare machine - centrifugal forced/induced draft fan scope. Industrial non-civil fans (boiler centrifugal ventilators etc.) remain attributed by clause 6.1.35 to the machinery volume.
• The Table C.7.8-7 items fall in two groups by airflow with identical descriptions but different labour/plant configuration; when compiling, check the selection against the grouping of the original standard tables.
• The fan itself and the supports supplied with it are equipment price / unpriced content, not carried in the installation consumption; bottom bedding is expressly excluded from the work content of the fan box installation items.

Further Reading

• DB11/T 2382-2024 "Consumption Standard for Construction Works", general building services installation works: section 6.1 machinery installation (6.1.33 to 6.1.39 fan installation; 6.1.2 excess-height efficiency reduction), section 6.7 ventilation and air-conditioning installation (6.7.2, 6.7.5, 6.7.17, 6.7.24)
• Annex C: Table C.7.8-7 fan box installation (C7-1-104 to 115); Table C.7.12-1 equipment support fabrication and installation (C7-1-172 to 174); Table C.7.12-2 mixed-flow (diagonal-flow) fan hanger fabrication and installation (C7-1-175 to 177)
• Related scenarios: fan coil unit installation (6.7.11); measurement conventions for equipment supports / bottom bedding (6.7.24)