Careful to choose flow switch for water chiller
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In the HVAC field, it is the premise of the normal operation of the main engine, to ensure the appropriate water flow in the medium and large central air conditioning system. Many projects have begun to require the differential pressure type water flow switch, so it has become an irresistible trend that the traditional target paddle type flow switch in the chiller will be replaced by differential pressure type flow switch.
It is very important to ensure the reliable operation of the compressor in the whole central air conditioning system. The condensers and evaporators of water chillers use water as the medium of secondary heat exchange, and proper water flow is the necessary guarantee for the normal operation of the main unit. Therefore, proper water flow detection methods and detection components are to ensure that the unit works under the condition that the system water flow is greater than the allowable minimum water flow, so as to avoid the failure of the air conditioning main unit.
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It is difficult to have a straight pipe section to ensure the installation of the traditional target type flow switch in the project site. The traditional target type flow switch have to be installed at the elbow or valve in the pipe flow system. As a result, the flow switch often misoperates or the target plate breaks during the operation of the water chiller, which seriously affects the normal operation of the water chiller. At present, it is not allowed in all the central air conditioning systems of electronic plants. The traditional target type flow switch is used instead of the differential pressure type flow switch.
According to this situation, “A.YITE TECH IN HONG KONG” introduced the differential pressure type flow switch into the application of medium and large water chillers to solve all the disadvantages of the target type flow switch:
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1. The area of ground water chiller room of differential pressure flow switch is generally small
2. The differential pressure type flow switch has no straight pipe section requirements for water pipes, which can save pipeline cost and installation cost.
3. Its pressure can be as high as 20bar, and the pressure of the traditional target flow switch is only 10bar. Although the pressure can be 16bar by increasing the thickness of the bellows, it is at the expense of the flexibility of the bellows, which increases the frequency of the misoperation of the target flow switch.
4. The differential pressure flow switch can be used in the primary pump variable flow system. For the consideration of energy conservation and environmental protection, many air conditioning systems adopt the primary pump variable flow system. The water flow of the air conditioning system is allowed to change within the range of 30% - 100%. The differential pressure flow switch can be set to protect under the rated flow of 30%. The traditional target flow switch cannot work normally at low flow rate.
5. Each action of the differential pressure flow switch is true and effective, which can reduce the water flow interruption caused by the sudden and unexpected stop of the water pump. The delay time set by the common target flow switch to prevent the misoperation is enough to make the static water in the evaporator of the water chiller freeze, while the differential pressure flow switch can avoid this situation without misoperation without setting the delay time 。
6. The differential pressure type flow switch can be used in the ice storage low temperature situation of - 20 ℃. If the water in the bellows of the traditional target type flow switch is lower than 0 ℃, the part outside the bellows that contacts with the atmosphere will be frozen, which will cause the target type flow switch to fail to operate. Even if the water temperature is not lower than 0 ℃, condensate will be generated on the target type flow switch, which will cause rust of metal parts and microswitch Rust and failure.