Orifice flowmeter, rotor flowmeter, Venturi flowmeter, measuring principle, respective Annubar flowmeter
It Annubar flowmeter:It is separated by a Annubar flowmeter root middle pipe, pipe detection ends with small holes, which leads to the small positive pressure fluid to the fluid along the side holes for suction side. When you encounter Annubar flowmeter detection fluid pipe, a fluid into the bull positive holes, the internal pressure is transferred to the positive pressure side tube through the detection tube. The same is due to the inertia of the fluid in the detection zone of negative pressure. But there is a small range of pipe back, the fluid flow is large, in the detection zone of negative pressure tube. Bull back longer, resulting in negative pressure is greater, the negative pressure delivered to the suction side pressure guiding pipe through the detection tube. The differential pressure transmitter converts the sampled differential pressure into electrical signal output. Because it has a direction detecting tube Annubar, attention must be paid to the installation in the installation direction.
Venturi flowmeter:The Venturi flowmeter consists of a section of Venturi tube. It is characterized by its inner diameter, big diameter and small diameter, and the big diameter at both ends is connected with the pipe. When fluid flows, if the flow rate remains the same, the pressure remains the same, which is the basic principle of fluid mechanics. When the fluid passes through the Venturi tube, the flow velocity of the fluid is accelerated due to its small inner diameter, which reduces the pressure. The pressure pipe is taken out and the pressure difference is formed by comparing with the pressure taken out at the entrance of the Venturi pipe, and then the differential pressure transmitter converts it into an electric signal output.
Rotor flowmeter:The rotor flowmeter is made up of a cone with an inner diameter, an outer circle tube and flanges at both ends, wherein the lower part is conical, and the upper part is cylindrical. When the fluid enters the lower part of the flowmeter, the upward thrust of the fluid causes the rotor to rise. Because the inner pipe of the flowmeter is conical, the rotor has an annular space between the floating pipe and the inner pipe, and the fluid bypasses the rotor from the annular space, and the flowmeter flows out from the upper part of the flowmeter. When the amount of fluid increases, the higher the height of the rotor floating, the ring space also increases. Therefore, the rotor flow meter is also called the equal area flowmeter, its rotor does not form the differential pressure between the upper and lower. Since the rotor in the flowmeter is up and down in the detection of flow, so when the installation of the rotor flow time, must keep the flowmeter is installed vertically, otherwise it will affect the accuracy of its detection.
Orifice flowmeter:The orifice plate is a ring made of stainless steel whose inner diameter is smaller than the inner diameter of the pipe and the outer warp is the same as the outer pipe of the pipe; the end face of the inner circle and the upper surface of the orifice plate is 90 DEG, and a chamfer is arranged at the lower end. When the fluid through an orifice in the round, due to fluid inertia, lower than the static pressure of the negative pressure pipe is formed between the lower end plate and pipe inner circle, so in the orifice of the upper and lower reaches for a differential pressure, the differential pressure of the fluid depends on the velocity, also is the size of the flow. The differential pressure of the upper and lower reaches of the orifice plate is taken into the differential pressure transmitter by a pressure guide pipe, and the differential pressure is converted into an electric signal by the transmitter. The orifice differential pressure guide pipe pressure is required, the positive pressure side pressure in the upstream orifice, orifice distance distance is a pipe diameter suction side pressure in orifice distance downstream, orifice distance of half a pipe diameter, a term called D-D/2. Because the orifice plate has a certain obstruction to the fluid in the fluid pipeline, we also call the orifice plate the throttling element. Because of the hole - plates downstream direction, the installation must pay attention to the installation direction.
