Installation arrangement and heat preservation method of branch pipe
1. Introduction and function of branch pipe
The branch pipe is also the central air-conditioning branch pipe, commonly known as the splitter (diverter). As the name implies, it is a pipe with one input but multiple outputs. Mainly used in the pipeline installation of the central air-conditioning VRV system. Its role is to divert the refrigerant in the pipeline to the indoor unit in the central air-conditioning multi-line installation system, playing a role of diversion.
The branch pipe connects the host and multiple terminal equipment (evaporators). There are gas pipes and liquid pipes. The diameter of the gas pipe is usually larger than that of the liquid pipe. The selection of the branch pipe is based on the indoor connection after each branch pipe. The capacity of the machine is determined.
2. Requirements of branch pipe
Usually the branch pipe is processed and welded with red copper pipe, which is very important for the selection and installation process of the branch pipe. Such as R410A refrigerant. Compared with traditional refrigerant, this refrigerant is more environmentally friendly, but its pressure is higher than that of traditional refrigerant. If it is not selected properly, it may leak and burst after installation.
Use 1mm thick copper pipe for diameters below 22.3, 1.3mm copper pipes for diameters below 31.8, and 1.5mm copper pipes for diameters above 35. The branch pipe should be uniform, regular, smooth, without false welding, and no desoldering. Welding installation will leave a lot of oxides, so the system must be nitrogen-filled welding, the pipe wall is clean, the inner wall has no black spots and no impurities.
3. Installation of branch pipe
requires attention! The branch pipe cannot be replaced by a tee, and the connection method cannot be reversed. Before installation, check whether the diameter of the copper pipe is consistent with the required branch pipe diameter.
The branch pipe has the following two arrangements:
When installed horizontally, the three ports are required to be on the same horizontal plane, and the included angle should not be greater than 15°; when installed vertically, it can be upward or downward. It is necessary to ensure that the three ports are on the same elevation, but tilt is not allowed;
note! The direction of the branch pipe and branch pipe must be the same, otherwise it will cause uneven distribution of refrigerant and affect the cooling and heating effect of the equipment.
Selection of branch pipe position:
The length of the straight pipe section between two adjacent branch pipes is not less than 500mm;
The straight pipe section before the main pipe port of the branch pipe is not less than 500mm;
The straight pipe from the branch pipe to the indoor unit is not less than 500mm.
note! Adequacy of the distance between straight pipe sections has a great influence on the equipment effect.
The distance between the branch pipe and the branch pipe should be more than 1000mm, otherwise it is easy to cause refrigerant drift and refrigerant flow noise.
note! After the branch pipe is welded, the pipeline should be kept pressure and leak tested, and the weld joint of the branch pipe should not be insulated before leak detection. Use nitrogen to maintain the pressure of 40kgf/c㎡. After 24 hours, there is no leakage before the branch pipe can be insulated. The insulation material must be the same as the pipeline.
4.Branch pipe case and analysis
Case: In a multi-connected central air-conditioning refrigeration piping system, a branch pipe cracked at the root of the elbow after 1 year of use. Replaced with a new branch pipe. After 1 year of normal use, the replaced branch pipe appeared to be the same again. malfunction. We made an anatomical analysis of the faulty branch pipe and came to the following conclusions. For reference.
Analysis of the cause: The branch pipe was not bent sufficiently when the copper pipe was connected to change its direction during installation. The elbow of the branch pipe was in forced operation, and the branch pipe had creeping fracture after a long time.
Force analysis
Anatomical diagram of the welded joint of the product
When the pipeline changes direction, the bend should be more than 0.5m away from the branch pipe (to buffer stress).
If the installation space is limited, the direction must be changed within 0.5m. The branch pipe should be protected from external force when connecting with the pipeline. At the same time, the two output pipelines of the branch pipe should be tightened appropriately with a flexible clamp to offset possible occurrences. External force
5.Insulation method of branch pipe
