1. Introduction of divergent tubes
The divergent pipe, also known as the air conditioning divergent, branch pipe, multi-line diverger, etc., is used for VRV multi-connected air conditioning system, connecting the main engine and multiple terminal equipment (evaporators), and is divided into air pipe and liquid pipe. The diameter of the trachea is usually thicker than that of the liquid tube. Note: Divergent tubes cannot be replaced with tees.
The air conditioner manifold is equivalent to the tee joint of the water pipe, which is used to divert the refrigerant, and the multi-connection manifold is used as an accessory to connect several air outlets. The selection of divergent tubes is determined according to the capacity of the indoor unit connected to each divergent tube.
2. Selection criteria for divergent tubes
The divergent tube is made of copper tube processing and welding, and it is also important for its selection. Such as R410A refrigerant, this refrigerant is more environmentally friendly than the traditional refrigerant, but its pressure is also greater than the traditional refrigerant, if the choice is not right, there may be leakage after installation, burst. It causes a lot of damage to the refrigeration system and causes unnecessary trouble.
Here are a few of the main reference standards:
Copper material: the divergent tube is mainly made of copper pipe, the quality of the copper tube directly determines the quality of the divergent tube, now many central air conditioners use R410A refrigerant, its working pressure is higher than the traditional refrigerant, so R410A special copper tube should be used, R410A copper tube is stronger than ordinary copper tube, the pressure resistance can reach more than 50KG, suitable for the operation of R410A Freon system pipeline.
Thickness: The thickness of the copper pipe used in the divergent tube should be determined according to the size of the diameter, the larger the diameter, the later the copper tube should be used. Under normal circumstances, 1mm thick copper pipes are used for diameters below 22.3, 1.3mm copper pipes are used for 31.8 and below, and 1.5mm copper pipes are best used for 35 and above.
Welding: The branch mouth of the divergent pipe is welded, and the weld is also the most prone to problems, a good divergent pipe should be uniform, regular, smooth, no virtual welding, no desoldering, etc
Oxide: During the processing of the divergent pipe, a large amount of oxide will be left, so it is necessary to pickle after processing to clean the oxides and other impurities inside and outside the pipe. A good split tube should have a clean wall, no black spots on the inner wall, and no impurities.
3. Installation of divergent pipes
If you understand the principle of central air conditioning refrigeration, you will know that there are 2 copper pipes connected to the indoor unit, one is a circulation gas and the other is a liquid, so the divergent pipe is generally divided into a gas pipe and a liquid pipe, also called a large tube and a small tube, as the name suggests, the gas tube is a gas, and the flow area of the relative gas is much larger than that of the liquid, so the gas pipe is also a large tube, and the liquid pipe is a liquid, so you can use a small tube.
The installation of divergent pipes is very important for the operation of the central air-conditioning multi-online system, and the installation specifications of divergent pipes should be observed on the basis of the correct selection of divergent pipes:
Divergent pipe connection: the inlet is connected to the outdoor unit or the previous branch, and the outlet is connected to the indoor unit or the next branch.
1. Before installation: Before installation, look at whether the diameter size of the copper pipe and the diameter size of the required divergence pipe are consistent, if the size of the copper pipe at the installation site and the diameter size of the required divergence pipe are different, then use a cutter to divide the different parts, note: choose the same diameter size to cut off. This article comes from the Refrigeration Encyclopedia.
2. Placement: When installing the divergent tube, try to place the divergent tube vertically or horizontally. When placed horizontally, the inclination deviation is ±10°.
When installed vertically: it can be up or down, to ensure that the three ports are on the same façade, and the tilt is not allowed.
3. Precautions: For the divergent pipe multiplex system, each pipe is labeled to make the connecting pipe after the branch correspond to the indoor unit to prevent wrong connection.
4. Purging: Blowing is to remove impurities in the pipe with nitrogen pressure. (Mainly dust, moisture, oxides caused by welding, etc.) ）
Fourth, the installation of divergent pipes precautions
The divergent pipe adopts a horizontal installation method, and the following matters should be paid attention to when installing:
1. The distance between the divergent pipe and its front and rear bends is too close: If the distance between the divergent pipe and its front and rear bends is too close, it will also affect the normal diversion of the refrigerant flowing through here, and the cooling effect of the indoor mechanism downstream will be affected. Therefore, it is necessary to ensure that the distance between the divergent pipe and its front and rear bends is more than 500mm (as shown below). Similarly, the distance between the two elbows (bending points) should be more than 500mm.
The spacing between the divergent tube and the divergent tube should be more than 1000mm; Otherwise, it is easy to cause refrigerant bias and refrigerant flow noise. (as shown below)
Divergent tube installation error cases:
Divergent tube installation example:
2. The pipeline direction is too complicated: the divergence of the main pipe coming out of the tube well on the first floor of the villa is too complicated, and some pipelines even go to one end and then turn back again, so that on the one hand, it wastes materials, and more importantly, it increases the resistance of the pipeline and reduces the refrigeration capacity of the indoor unit; Some pipelines are laid in stacks, which is not conducive to the normal oil return of the system, which will leave hidden dangers to the normal operation of the main engine. Regarding the design and laying of pipelines, please follow the principle of "the length of the pipeline is as short as possible, and the elbow is used as little as possible", otherwise it will affect the normal operation of the unit in the future, and even damage the unit, so it must be changed. This article comes from the Refrigeration Encyclopedia.
3. The outlet pipe does not retain a certain straight section: we often find this problem at the construction site: the pipeline separated from the divergent pipe does not retain a certain straight pipe section, but bends immediately after the separation, which will have a great impact on the indoor unit behind the divergent pipe.
4. Welding of divergent pipes: In the actual engineering maintenance, we found that the last two A and B of a set of 12 multi-connected indoor units, when A is opened, the refrigeration effect of B is poor, and if A is not opened, then B is good, so we will take off the last divergent pipe together with the pipeline connecting B, and cut the suspicious pipeline to find the situation, and after shortening the insertion depth treatment, the unit is running normally. (There are peers in the refrigeration encyclopedia technology exchange community who have asked about this kind of fault several times, which shows that the on-site construction personnel need to pay more attention)
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