Balancing valve is a valve which can adjust static or dynamic balance under hydraulic condition. Balance valve is mainly used to regulate the flow rate. Balance valve is equivalent to a resistance element in the water system.
As far as the HVAC water system is concerned, the flow of water in the pipeline is resistive, and the resistance increases gradually with the extension of the pipeline, and the water will naturally flow to the place where the resistance is small, resulting in the flow obtained by different pipelines far from the engine room can not meet the actual needs of the system, that is, the flow of the nearby pipeline is too large, and the flow of the remote pipeline is too small, which is manifested as different areas of a building. The indoor temperature is uneven. Balance means to balance the resistance of different pipelines in the system by some method or product, and to ensure that each pipeline of the system obtains the actual flow needed. The ultimate goal is to make the indoor temperature of the whole building reach equilibrium.
Design of Balancing Valve
Balancing valves in the main engine room are best on the equipment table.
Technical Requirements for Bidding of Balance Valve
1. Function and Technical Requirements of Static Balance Valve
1) The static balance valve should have the function of regulating hydraulic balance between parallel circuits, and should also have the function of turning off.
2) Valve characteristic curve should have equal percentage regulation characteristics.
3) The static balance valve body should have a special water-proof pressure gauge, with special tools, to accurately measure the flow of pipelines on site. In order to facilitate the commissioning work, the measurement channel should be on the same side of the valve body and ensure that the pressure difference between the inlet and outlet of the valve is measured.
4) In order to ensure the balance state of the water system after commissioning, the static balance valve should have the maximum opening and locking function.
5) Flow Control Accuracy: When the opening is 50-100%, the error is less than (+5%).
6) Work pressure: PN16
7) Working temperature: -10-120 C
8) Valve body material: DN15-DN50: copper alloy > DN50: cast iron (PN16) or ductile iron (PN25)
2. Function and Technical Requirements of Dynamic Differential Pressure Balancing Valve
1) It can stabilize the flow and differential pressure of the branch, has adjustable flow or differential pressure setting point, and has shut-off function.
2) It has measuring points for system diagnosis, can set flow or pressure difference on site, and has on-site monitoring means.
3) Work pressure: PN16
4) Working temperature: -10-120 C
5) Valve body material: DN15-DN50: copper alloy > DN50: cast iron (PN16) or ductile iron (PN25)
3. Function and Technical Requirements of Dynamic Flow Balancing Valve (Fixed Flow Valve)
1) The dynamic flow balancing valve should have the function of maintaining the constant flow in the pipeline of the water system.
2) Flow control accuracy, error less than (+5%)
3) Work pressure: PN16
4) Working temperature: 0 ~120.
5) Working pressure difference range: 14-220 kPa or 34-276 kPa
6) Material: Valve Body: DN15-DN50: Copper Alloy (> DN65): Ductile Iron
Valve gallbladder: stainless steel
7) In order to ensure the normal operation of the system, under the premise of meeting the design flow rate, the valve resistance is less than 35kPa.
4. System Deepening Design and System Debugging Requirements
1) After winning the bid, the tenderer shall conduct hydraulic calculation and inspection by the balance valve manufacturer according to the air-conditioning water system diagram and provide the hydraulic balance calculation sheet.
2) All the bidding companies should have the ability to debug the hydraulic balance system. They should have special debugging instruments, professional debuggers and provide the water balance debugging plan when bidding.
3) All bidders should have the Chinese version of intelligent debugging instrument, which should be used for flow measurement, differential pressure measurement and temperature measurement.
4) The supplier shall provide the balance debugging report which is formally approved by the user. The debugging report shall include the measured flow, the designed flow, the valve opening, the flow deviation and so on.
5) Debugging must be done by professionally trained personnel.
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