Correction measures: bimetallic dial thermometer should be used, and the point should be set nearby.
Corrective measures: the flexible short pipe of the smoke exhaust system must be made of non combustible materials; it shall not be made of ordinary canvas, but shall be made of silicon titanium or glass fiber flexible connection (non combustible test is required).
Compensation measures shall be taken when the air duct passes through the building deformation joint.
Problem: the condensate of air conditioning unit is not provided with water seal, There is a large amount of water in the machine room during shutdown.
The method of passing through the firewall, the method of passing through the floor and the method of going out of the roof: the side length or unilateral area of the air duct is larger than the specification, no reinforcement measures are taken, and vibration and noise are generated during operation.
The ground of the machine room on the floor should be waterproof.
The figure shows “Three Prevention cloth” for air supply and exhaust ducts The fabricated flexible short pipe and connection method the air-conditioning fan and the air duct shall be connected by flexible short pipe, the flanges on both sides shall be parallel and not misplaced, and the short pipe spacing shall be 150 ~ 300mm.
About the production and installation of air duct 1: the protective sleeve is not set in the fire-proof and explosion-proof wall and floor slab or the protective sleeve is too thin.
The spacing between supports is 4.56M, More than 3m (specification requirements).
Correct practice: the chilled water pipeline shall be laid vertically, the manufacturing and installation of load-bearing support, the distance between casing and pipeline in the drawing must be greater than the thickness of pipeline insulation layer, the floor support and accessories shall be welded with reinforcing plate, the accessories of large-size chilled water pipeline shall be provided with floor support, the support shall be isolated, the heat-conducting rubber gasket shall be flush with the steel plate, and the surface shall be smooth.
Corrective measures: strictly implement Article 6.2.1 of GB50243 1 mandatory provision stipulates that when the air duct passes through the fire-proof and explosion-proof wall or floor that needs to be closed, the pipe or protective sleeve shall be embedded, the thickness of the steel plate shall not be less than 1.6mm, and the flexible material that is non combustible and harmless to human body shall be used between the air duct and the protective sleeve.
The condensate drainage pipe in the surface cooling section shall be provided with a water seal, and the height of the water seal shall be greater than the wind pressure to facilitate condensate discharge, At the same time, internal air in the machine room shall be prevented from entering the unit (measures must be taken to prevent air backflow due to dry condensate in winter).
When the diagonal length of the air duct is less than 1500mm, two angle steel and two pull rods shall be used to fix the air duct, and the air duct shall be fixed on the angle steel with bolts, solid rivets or self tapping screws; When the diagonal length of the air duct is ≥ 1500mm, the air duct shall be fixed with angle steel around, and the air duct shall be fixed on the angle steel corresponding to the long side of the air duct with bolts, solid rivets or self tapping screws.
The glass magnesium air duct and fan shall be connected by flexible short pipe.
For example, when the fan pressure is 800pa and the condensate pipe diameter is 50mm, H1 ＞ 800 / 10 + 50 = 130mm and H2 ＞ 800 / 10 / 2 + 50 = 90mm.
Cause analysis: the application conditions of the flexible connection materials used in the general ventilation system and the fire control and smoke exhaust system are confused, and the on-site management is not in place.
The distance between pipe butt weld and support and hanger shall be greater than 50mm.
Problem: the thermometer setting and selection is unreasonable, and the temperature test value is inaccurate.
Cause analysis: the understanding of the drawings is not thorough, and the on-site construction is random.
Corrective measures: the general design of civil installation does not provide the processing and installation drawing of support and hanger.
Problem: the thermometer on the expansion water tank The connection point between the expansion pipe and the system pipeline is not set near the suction inlet of the circulating water pump according to the construction drawing, and the water pump produces “cavitation”..
Problem: the quality of the installation of the flexible connection of the air duct.
Problem: the setting of equipment piping supports and hangers in the machine room is unreasonable.
2.
Floor mounted combined air handling unit: 1.
Cause analysis: the water seal is not set according to the design requirements, the ponding pan is under negative pressure, and the water seal height shall overcome the negative pressure height.
(gb50738-2011 code for construction of ventilation and air conditioning engineering) Section 11.2 Article 5.3: the distance between pipeline interface weld and the edge of support and hanger shall not be less than 100mm).
Every time they find a quality problem, they verbally say that the problem is not big.
Preventive measures: generally, the pipeline in the machine room is suspended by the horizontal main pipe, and the horizontal three ends are connected with the ground equipment.
Before construction, the installation and civil engineering drawings shall be combined to determine which walls and floors in the project have fire protection requirements, and the protective casing shall be set to cooperate with embedding in the civil structure construction.
Corrective measures: pipeline welding shall be in accordance with article 9.3.1 of GB50243 Article 2: the assembly and groove form of pipe butt welded junction shall comply with the provisions in the following table; The straightness of the butt joint is 1 / 100, and the total length is no more than 10mm.
On the installation quality of air conditioning water system: pipe welding.
In order to reduce the cost, the residual material of 0.75-1.2mm is used.
Don’t panic, but it will eventually affect the actual use and even delivery.
Cause analysis: the pipeline is misaligned, there is no gap between the pipeline counterparts, the end face of gas cutting blanking of the pipeline is uneven, the gap width is incorrect or the groove is not made, resulting in the pipeline is not easy to weld through, the welding slag is not cleaned in time after the pipeline is welded, and the antirust paint is directly applied.
The reason analysis: it is considered that the thickness of the sleeve has little to do with it.
Cause analysis: the setting of equipment piping supports and hangers in the refrigeration room is unreasonable, and the anti cold bridge measures are not taken for the chilled water pipe supports.
Cause analysis: it is considered that the edge or cross-sectional area of the air duct has no direct impact on the operation, and the construction unit considers saving costs and cutting corners.
The fixed welded junction of the pipeline shall be far away from the equipment and shall not coincide with the center line of the equipment interface.
The flexible short pipe of the smoke exhaust air duct shall be made of non combustible material.
Corrective measures: the water seal height of the condensate discharge pipe of the air conditioning unit shall meet the drainage requirements.
Corrective measures: according to Article 4.2.1 of GB50243-2002 Article 10 stipulates that the rectangular side length is about 630mm, the side length of thermal insulation air duct is greater than 800mm, the pipe section is greater than 1250mm, or the area of low-pressure air duct is greater than 1.2m2, and the medium and high pressure is greater than 1.0m2, reinforcement measures shall be taken.
People who have contacted the construction party know that they are very “cunning”.
When the air duct is manufactured, the corner treatment is not in place, the connecting bolt spacing of the air duct shall be less than 150mm, the thickness of the sealing gasket shall be no less than 3mm, and the bolt direction shall be consistent, The length of the nut is 2-3 buckles.
