1. As the title shows, let’s briefly understand what a central air-conditioning system is:
1. The central air conditioning system is composed of one or more cold and heat source systems and multiple air conditioning systems. This system is different from traditional refrigerant air conditioners (such as single unit, VRV) to centrally process air to meet comfort requirements. The principle of liquid vaporization and refrigeration is used to provide the required cooling capacity for the air conditioning system to offset the heat load of the indoor environment; the heating system provides the required heat for the air conditioning system to offset the cooling and heating load of the indoor environment.
2. What is a fan coil:
Fan coil unit is abbreviated as fan coil. It is one of the end devices of the air conditioning system composed of small fans, motors and coils (air heat exchangers). When chilled water or hot water flows through the coil tube, it exchanges heat with the air outside the tube, so that the air is cooled, dehumidified or heated to adjust the indoor air parameters. It is a commonly used terminal device for cooling and heating.
3. What is a soft metal connection:
Metal soft connection is an important connection component in engineering technology, which is formed by the combination of corrugated flexible pipe, net sleeve and joint. Used in various gas and liquid pipeline systems and length, temperature, position and angle compensation systems as compensation components, sealing components, connection components and shock absorption components, used in aerospace, petrochemical, mining electronics, machinery and shipbuilding, and medical Health, textile and electronics, energy construction and other fields.
2. Why should a hose connector be installed on the fan coil unit:
The chilled water of the central air conditioning system circulates continuously in the pipeline. The temperature of the pipeline blows out the cold air through the work of the fan coil. The work of the fan causes the pipe to produce vibration and noise. In order to better satisfy the quietness of each fan coil, Install hose joints at the inlet and outlet of each fan coil, which can greatly reduce vibration and noise. In addition, install 4 hanging spring shock absorbers above the fan coil, so that the fan coil can be completely connected to the floor. The piping system is isolated to achieve the effect of fan vibration and no vibration of floors and pipes.
3. What should be paid attention to in the central air-conditioning system of the soft metal connection:
Flexible metal connections should be easy to check regularly. I suggest that the work of a soft metal connection is compression, not tension, and no torsion is allowed.
Please install an effective chlorine ion removal device at the water inlet of the pipeline (chloride ion content does not exceed 25mg/l) to avoid excessive chloride ion content in the water and pinhole corrosion.
4. Summary:
According to the above photos, the analysis result of the technical department of our factory:
The central air-conditioning system fan coil is in normal operation, and the chloride ions in the water flow in the pipeline. When the equipment stops working and is in a static state, the chloride ions in the water will adhere to the inner wall of the corrugation, causing pinhole corrosion. Due to the small diameter and the wall thickness of the corrugation is less than 1mm, the chloride ion will quickly corrode the corrugation on the inner wall of the corrugation. There are salt in the air-conditioning water, sodium chloride in the salt, and chloride ions in the sodium chloride. Stainless steel 304 is not resistant to chloride ions.
5. The solution given by the technical department of our factory:
1. Install a chloride ion elimination device in the pipeline to ensure that the chloride ion content of the circulating water does not exceed 25mg/l;
2. Replace the metal soft connection with a PTFE lined metal hose;
3. Replace the metal soft connection with a rubber hose;
