Product introduction of constant air volume air valve
Category : Blog
Constant air volume valve is a mechanical self-operated device suitable for ventilation and air conditioning systems that require constant air volume. The air volume control of the constant air volume valve does not require external power. It relies on the air flow in the air duct to position the control valve, so as to maintain the air flow at the preset flow rate in the entire pressure difference range.
Classification of constant air volume valve
One is to sense the air flow through the air duct through the silicone airbag in the balancer, and automatically shrink and expand according to different static pressures to achieve a constant air volume. When the static air pressure at the inlet and outlet is the smallest, the air bag is in a contracted state. When the static pressure at the air inlet and outlet increases, the air bag begins to expand, thereby reducing the gap around the air bag. Keep the flow constant within a certain wind pressure range.
The other type is a mechanical self-contained device, which relies on the airflow pressure in the air duct to locate the position of the control valve, so as to maintain the airflow at a preset flow rate within a certain pressure difference range. It does not require external power, and an electric actuator can be added to change the flow setting through remote control signals.
Application of variable wind system
In the variable air volume air-conditioning system, generally the outer area adopts the variable air volume method, and the inner area adopts the constant air volume method. In an air supply system with constantly changing air volume and air pressure, the constant air volume design of the inner area is inseparable from the constant air volume valve.
Exhaust system application
A good air conditioning system design, its exhaust system must be very reasonable, and this is often overlooked. In civil buildings, especially in high-rise buildings, the airtightness of the envelope structure is very good, and the positive pressure value of the room can be maintained with less air volume. About 85 to 90% of the fresh air volume must be discharged outdoors through organized exhaust air, so as to ensure the balance of air supply and exhaust air, otherwise no amount of fresh air can be sent into the room. In civil buildings, exhaust air is generally discharged outdoors through auxiliary rooms such as toilets and boiling water rooms. In addition, sometimes an exhaust system should be added to ensure the balance of air supply and exhaust.
Features
The constant air volume valve is an automatic mechanical mechanism that does not require external power. An additional electric actuator can be added to change the flow setting through remote control signals. The constant air volume valve can be used in air supply and exhaust systems. The working temperature is generally 10 to 50 °C, and the pressure difference range is 50 to 1000 Pa, that is, at least 50 Pa pressure difference is applied before the valve and behind the valve, otherwise the constant air volume valve cannot work. This should be noted, because the wind pressure value of the fresh air unit of the fresh air system is generally not large. The fixed air volume valve is not limited by position when installed, but the valve shaft should be kept horizontal. Generally, a straight inlet air duct with a distance of 1.5 times the long side of the valve and a straight outlet air duct with a distance of 0.5 times are required.
The constant air volume valve has high control accuracy, an external pointer shows the flow scale, the adjustment accuracy is about ±4%, and the current limiting mechanism does not need maintenance. Just as the balance valve is more and more adopted by the majority of designers in the air-conditioning water system, the constant air volume valve will also be widely used in the air supply and exhaust system due to its precise adjustment and automatic balance characteristics.
Air Duct Application
In an all-air system, due to the influence of building conditions, the resistance between the branch pipes must be unbalanced. Generally, a three-way regulating valve or a split multi-leaf regulating valve is used to complete the air volume distribution. In order to ensure that the air volume in important rooms or main branch pipes will not be too large or too small, and reduce the blindness of debugging, a set air volume valve can be appropriately added to replace the three-way regulating valve or the split multi-leaf regulating valve.
Purification system application
It is very important to maintain the positive pressure value of the clean room in the purification air conditioning system. Adding a set air volume valve in the exhaust or air supply and exhaust system can effectively ensure the positive pressure value of the clean room. The clean operating room needs to maintain positive pressure in the operating room during and when the operation is not in progress. The fresh air volume during the operation is the fresh air volume required to ensure the positive pressure plus the fresh air volume required by the personnel. When the operation is not in progress, the fresh air volume is only to ensure positive pressure. The required fresh air volume, so a double-position fixed air volume valve needs to be set on the fresh air duct.