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Fixed air valve in the ventilation and air conditioning system applications
Fixed air volume valve, is a mechanical self-force device, suitable for fixed air volume ventilation and air conditioning systems. Air Volume Control Air flow control does not require additional power, it relies on air flow within the duct to position the control valve to maintain airflow at a pre-set flow rate over the entire pressure differential. (A) the application in the fresh air system At present, in our country, the fan coil plus fresh air system air conditioning is still more common, especially in the hotel room part, most of the office buildings, office buildings have adopted this approach. The usual practice is to set up a fresh air unit at each level. The walkway should be laid with fresh air pipes, and dozens of branch pipes are respectively connected to the rooms from the main pipe. To hotel rooms, for example, each room fresh air volume is generally 100 m3 / h, how to achieve the same amount of air flow in each branch it? In general, designers often add an air flow control valve to the fresh air branch pipe, expecting to finish the air flow distribution through later debugging means. Because the fresh air system is generally dry pipe length, branch pipe is short, and the air volume control valve regulation is neither intuitive nor the regulation accuracy is not ideal Moreover, each room fresh air volume is only 100 m3 / h, the air volume is very small, this debugging almost Can not be completed. The construction unit can only measure the total amount of air delivered by the fresh air mains and ensure that there is a sense of airiness in the air supply branches. In order to ensure that the amount of fresh air delivered in each room can reach the design value, and there is no need for the construction unit to go to the balance of a room again, we only need to add a fixed air volume valve on each fresh air branch pipe to solve the above problems. People living in high-rise buildings, office workers often worry about the lack of fresh air, and designers often feel very aggrieved. Because from the drawing point of view, the value of the new air volume standard is not low, but we often overlook a problem, how to ensure the actual effect from the design point of view, and air volume valve in the fresh air system is a powerful measure. Due to the current air volume valve is still mainly rely on imports, the price is more expensive, I suggest four or five-star hotels, high-end office use more appropriate. (B) the application in the exhaust system A good air conditioning system design, its exhaust system must be very reasonable, and this is often not valued. In civil buildings, especially in high-rise buildings, the containment structure is airtight and requires only a small amount of air to maintain the positive pressure of the room. About 85-90% of fresh air volume must be discharged through the organized exhaust air outdoors, so as to ensure that the air supply and exhaust air volume balance, or more fresh air volume can not be sent to the room. In civil buildings, exhaust air generally through the bathroom, boiled water and other auxiliary room out of the room. In addition, sometimes an additional exhaust system should be added to ensure delivery and exhaust ventilation. For the bathroom exhaust, the usual practice is to set up one or two bathroom ventilators in each bathroom, interlocking with the exhaust fan on the exhaust shaft. We know that the fresh air system in high-rise buildings should be operated all year round, and the corresponding exhaust system should also be operated all year round. In other words, people who use the bathroom can not control the opening of the bathroom ventilator, there is no need to set up the bathroom ventilator. Moreover, a big fan with dozens of small fan exhaust system operation is difficult to match, but not economical. Exhaust volume of 400m3 / h bathroom fan noise about 40dB, so that the bathroom lost its peace. A large number of bathroom ventilators also bring great trouble to maintenance. In order to solve this problem, we can cancel the bathroom ventilator, add a fixed air volume valve on each branch of the exhaust shaft, and an exhaust fan on the top of the shaft. This exhaust system, to ensure that all levels of the exhaust volume is roughly equal, and the system control is simple, reliable operation, the bathroom can be very quiet. (C) in the VAV air conditioning system In the VAV air conditioning system, the general use of variable air volume outside the way, the inner area with a fixed air volume, air volume, air pressure in the changing air supply system, the inner zone set Air volume design is inseparable from the fixed volume valve. (D) in the purification of air-conditioning system In the purification of air-conditioning system to maintain a clean room of the positive pressure value is crucial in the exhaust or send exhaust system plus set the amount of air valve, you can effectively ensure the clean room of positive pressure value. Clean operating room When the operation is performed with or without the need to keep the operating room positive pressure, when the operation of fresh air volume to ensure positive pressure required fresh air volume plus staff required fresh air volume, the operation is not carried out when the amount of fresh air is only guaranteed positive pressure The amount of fresh air required, so the need to set a new air duct set double-volume valve. (E) the balance of the air duct in the air system In the whole air system, due to the impact of the construction conditions, the resistance between the branches certainly not balanced, the general use of three-way control valve or leafy multi-leaf control valve to complete the air volume distribution. In order to ensure that the air volume in an important room or main branch pipe will not be too large or too small, the blindness of debugging may be reduced and the air volume valve may be appropriately set to replace the three-way control valve or the multi-leaf control valve. (F) the use of fixed air volume features Fixed air volume valve is an automatic mechanical institutions, without external power, plus an electric actuator by remote control signal to change the flow setting. The fixed air volume valve can be used in both sending and exhausting systems. The working temperature is generally 10-50 ℃ and the pressure difference is 50-1000Pa. That is, at least 50Pa differential pressure is applied after the valve before the valve, otherwise the fixed air volume valve can not work. It should be noted that, because the fresh air system, the fresh air unit wind pressure values ​​are generally not large. The fixed air volume valve is installed without position limitation, but the valve shaft should be guaranteed level, usually require 1.5 times the length of the linear inlet duct and 0.5 times the distance straight outlet duct. The fixed air volume control valve has high control precision, and the external pointer shows the flow scale. The adjustment accuracy is about ± 4%. The current limiting mechanism does not need to be maintained. For the matching with the system, the fixed air volume valve can be rectangular, circular, thermal insulation, Just as the balancing valve is more and more used by the majority of designers in the air-conditioning water system, the constant-air valve has been widely used in the air-sending and exhausting systems due to its characteristics of being accurately adjustable and automatically balancing.