With the government authorities in accordance with the 'building smoke and exhaust system technical standards' GB 51251-2017 specification of smoke and exhaust fire-resistant duct fire resistance limit design and implementation of further strict requirements, the current smoke and exhaust fire-resistant duct application form of good and bad, this paper is based on the smoke and exhaust duct engineering practice related to the thinking of the current market use of fireproof coatings, rock wool, the external cladding fireproofing materials, the integration of the air duct to analyze.

Galvanized iron + rock wool + fire prevention board belongs to the original traditional way of fire duct production, as shown in Figure 1. Early through the firewall or partition wall has been used, galvanized iron duct production, iron outside the paste rock wool, rock wool exterior and then laying fire prevention board.

The body of all on-site production, the site workload is huge; rock wool thickness of 50mm, fire prevention board for 8-12mm, occupying a large space, the structure is not solid; due to on-site production, there may be safety hazards; fire prevention board exposed, not adapt to the humid environment; due to all on-site production, the assembly rate is very low, the high cost of labor, the cost is high.

This way of galvanized iron made on site, iron outside the high-temperature centrifugal cotton, centrifugal cotton thickness of 50mm, occupying a large space, the site of the workload, centrifugal glass wool outside and then wrapped in aluminum foil veneer, the production method is similar to the air-conditioning ducts + centrifugal glass wool + aluminum foil.

If set in the underground garage and other exposed space, the aluminum foil is easily damaged, resulting in exposed heat insulation layer, poor durability, and affects the appearance, the production process of artificial workload.

The product test report shows that the weight of the specimen is obviously too heavy unreasonable, for example, 1.0mm thick steel plate is 8kg / ㎡, 50mm thick glass wool weight 2.5-4kg / ㎡, why the specimen in the test report on the weight of up to 30kg / ㎡? One can't help but question whether so much heat-insulating adhesive is also applied during on-site production, and whether it can pass the re-inspection.

此产品被认为是规范从严实施时间不明晰，现场镀锌铁皮已经制作吊装完成，情理上无法拆除，为尽力迎合新规范验收条件，不得已而为之采取补救措施的过渡产品。

类似于棉被一样，内部芯是棉絮状的硅酸盐。硅酸盐纤维卷毡状，大面积安装无法确保平整度，观感太差，内部纤维分散，铝箔破损或燃烧后内部纤维会飘落。

  

铁皮+漂珠硅酸钙+岩棉三层复合的工业一体化复合板，还是铁皮风管的包裹材料，需要包覆在铁皮风管上，作为复合型包裹材料并不能降低铁皮厚度。在这样的厚度下是可以达到耐火极限的，但成本过高。

Can only factory assembly finished products, can not site processing, can not be flexible to face the site changes, color steel plate thickness of 0.3-0.5mm or so, the strength in the application to the large diameter duct is slightly insufficient. Fireproof insulation for the sandwich material, the intermediate sandwich material, thickness, full of degree can not visually check, the material can not be replaced in a timely manner after the decay of moisture.

To sum up, whether it is fireproof coating or glass wool products directly as a smoke pipe fireproof material can not stand up to scrutiny; fire insulation outside the parcel material is also subject to the cost of labor, the material itself, the limitations; integration of composite air ducts are a mixed bag of good and bad, should be from the characteristics of the material, the type of inspection and other aspects of strict control. The market is in urgent need of a fireproof and heat insulation performance is stable under the premise of meeting the national standards, the site can be flexibly processed, low-cost fireproof air duct solutions.