How to choose Flow Measurement InstrumentThe flow detection is installed on the test pipe of DN65, no matter how big the rated flow rate of the pump is, it is installed on DN65 pipe, is it appropriate to do so？ can the flow rate of the pump be detected effectively? Of course not! When the pump flow is large, DN65 pipe diameter simply cannot meet the requirements. !
According to the provisions of the fire protection code: when the flow of a single fire protection pump is no more than 20L/s and the design working pressure is no more than 0.5mpa, the pump set shall reserve the flowmeter and manometer interface for measurement, and other pump sets shall set the flow and pressure testing device of the pump set. The measuring accuracy of the flow detection device of the fire pump shall be level 0.4, and 75% of the maximum range shall be greater than 175% of the designed flow value of the maximum fire pump. The measuring accuracy of the pressure detection device for fire pump shall be 0.5, and 75% of the maximum range shall be greater than 165% of the maximum design pressure of a fire pump.
The flow test device is generally used to regularly test the water outlet capacity of the fire pump, to detect whether the water outlet capacity of the fire pump is reduced, if the water outlet capacity of the fire pump is reduced, it will not meet the requirements of the fire outlet. The diameter of the flow test device shall generally be the same as or similar to that of the water outlet of the pump
The fire code has very high requirements on the accuracy and range of the flow test device. The accuracy is required to be 0.4, and the range is required to be 2.33 times of the maximum water output of the pump. Because of the high technical difficulty, this kind of flow measurement instrument cannot be produced in China. At present, only EU-106 series flowmeter of A.YITE brand can meet this requirement.
The fire code does not require the flow test device to be installed in the test pipe. Our technicians have contacted many design institute designers who have installed the flowmeter in the outlet pipe of the pump (in the middle of a straight pipe far from the outlet of the pump). Because the diameter of the water test pipe is only DN65, if the water pump is DN150 or DN200, then because the water test pipe is too small, the water will not flow out properly, causing water resistance, that is, because the water pipe suddenly becomes smaller, the water cannot flow out normally, the water capacity of the pump is artificially inhibited.
The main purpose of the flow test device is to test whether the actual working conditions of the water pump meet the design requirements. The setting position can be flexible and can be set on the outlet main pipe. If they are all installed in DN65 calibre, the large test flow will exceed the water pipe load limit flow, affecting the water output, unable to accurately measure the water pump flow.
Therefore, the author suggests that the installation of the fire flow test device should not be limited to the test pipe, can be installed in the water pump above the main pipe. In addition, the author suggests that the designer choose the eu-106 series flow test device of Hong Kong ayit brand, which has stable performance, high precision and far greater range than ordinary flowmeter products.
About the fire pressure test device, the Hong Kong A.YITE brand GE-204 series products, can meet the fire requirements