Constant air volume valve
The utility model is a mechanical self-supporting device, which is suitable for the ventilation and air conditioning system requiring constant air volume. The constant air volume valve does not need external power to control the air volume. It relies on the air flow force in the air duct to locate the position of the control valve, so as to maintain the air flow at the preset flow within the whole pressure difference range.
I. application in fresh air system
At present, in China, the air conditioning mode of fan coil plus fresh air system is still relatively common, especially in the guest rooms of hotels, most office buildings and office buildings adopt this mode. The common practice is to set up fresh air units on each floor, lay fresh air main pipes in the walkway, and connect dozens of branch pipes from the main pipe to each room.
Take the guest room of the hotel as an example: the fresh air volume of each guest room is generally 100m? / h, how to make the air volume of each branch pipe consistent?
Generally speaking, the designer often adds an air volume regulating valve to the fresh air branch pipe, expecting to complete the air volume distribution through later debugging means. In general, the fresh air system is characterized by long main pipe and short branch pipe, while the adjustment of air volume regulating valve is not intuitive and the adjustment accuracy is not ideal. Moreover, the fresh air volume of each guest room is only 100 m3 / h, and the air volume is very small, so the commissioning is almost impossible.
People who live and work in high-rise buildings often worry about the lack of new air volume, while designers often feel aggrieved. As seen from the drawings, the value of fresh air volume standard is not low, but how to ensure the actual effect from the design point of view is ignored, and the application of constant air volume valve in the fresh air system is a powerful measure.
II. Application in exhaust system
A good air conditioning system design, its exhaust system must be very reasonable, and this is often ignored. In civil buildings, especially in high-rise buildings, the air tightness of the enclosure is very good, and the positive pressure value of the room can be maintained with less air volume. About 85-90% of the fresh air must be discharged out of the room through organized exhaust, so as to ensure the balance of air supply and exhaust, otherwise no amount of fresh air can be delivered into the room. In civil buildings, the exhaust air is generally discharged out of the room through the toilet, boiled water room and other auxiliary rooms.
In addition, sometimes a set of exhaust system should be added to ensure the balance of air supply and exhaust. For toilet ventilation, it is usually done that each toilet is equipped with one or two toilet ventilators, which are interlocked with the exhaust fans on the exhaust shaft. We know that the fresh air system in high-rise buildings should be operated all the year round, and the corresponding exhaust system should also be operated all the year round. That is to say, people who use the toilet can't control the opening of the ventilator in the toilet, so it's unnecessary to set the ventilator in the toilet.
Moreover, it is difficult to match and uneconomical for a large fan with dozens of small fans. The noise of the ventilator in the toilet with the exhaust air volume of 400m3 / h is about 40dB, which makes the toilet lose its tranquility. A large number of toilet ventilators also bring great trouble to maintenance. To solve this problem, we can cancel the ventilator in the toilet, add a constant air volume valve on the branch pipe of each floor of the exhaust shaft, and set a exhaust fan on the top of the shaft. This kind of exhaust system can ensure that the exhaust air volume of each floor is approximately the same, and the system control is simple, the operation is reliable, and the toilet can be very quiet.
III. application in VAV air conditioning system
In the VAV air conditioning system, the VAV mode is generally adopted in the outer area and the constant air volume mode is adopted in the inner area. In an air supply system with constantly changing air volume and air pressure, the constant air volume design in the inner area is inseparable from the constant air volume valve.
IV. application in purification air conditioning system
It is very important to maintain the positive pressure value of clean room in the purification air conditioning system. The positive pressure value of clean room can be effectively guaranteed by setting the air volume valve in the exhaust or supply exhaust system.
The positive pressure of the operating room shall be maintained during and during the operation in the clean operating room. During the operation, the fresh air volume is to ensure the fresh air volume required by the positive pressure plus the fresh air volume required by the personnel. During the operation, the fresh air volume is only to ensure the fresh air volume required by the positive pressure, so the double position constant air volume valve shall be set on the fresh air pipe.
V. application in air duct pipeline balance
In the whole air system, due to the influence of the building conditions, the resistance between the branches is definitely uneven. Generally, three-way control valve or split multi leaf control valve is used to complete the air distribution. In order to ensure that the air volume on the important room or main branch pipe is not too large or too small and reduce the blindness of commissioning, the air volume valve can be set appropriately to replace the three-way regulating valve or the opposed multi leaf regulating valve.
Vi. features of constant air volume
The constant air volume valve is an automatic mechanical mechanism, which can change the flow setting by adding an electric actuator through remote control signal without external power. The constant air volume valve can be used in the air supply and exhaust system. The working temperature is generally 10-50 ℃, and the pressure difference range is 50-1000pa, that is, at least 50pA pressure difference shall be applied behind the valve in front of the valve, otherwise the constant air volume valve cannot work. It should be noted that the wind pressure value of the fresh air unit of the fresh air system is generally not large.
When installing the constant air volume valve, it is not limited by the position, but the valve blade shaft shall be level. Generally, it is required to have a straight inlet air pipe 1.5 times the distance of the long side of the valve and a straight outlet air pipe 0.5 times the distance. The control accuracy of the constant air volume valve is high, with external pointer to display the flow scale, and the adjustment accuracy is about ± 4%. The current limiting mechanism does not need maintenance. In order to match the system, the rectangular, circular, heat preservation and noise elimination types of the constant air volume valve can be selected.
Source: HVAC