Rotameters are used for small pipe diameters and low flow rates. The diameter of commonly used instruments is below 40-50mm, and the minimum diameter is 1.5-4mm. 稍高些，流速在0.5-1.5m/s之间。 It is suitable for measuring low flow rate and small flow rate. Taking liquid as an example, the nominal pipe diameter of full-scale flow rate of glass tube float flowmeter with a diameter of less than 10mm, the flow rate is only between 0.2-0.6m / s, even lower than 0.1m / s; metal The tube rotor flowmeter and the glass tube rotor flowmeter with a diameter greater than 15mm are slightly higher, and the flow rate is between 0.5-1.5m / s.
Rotary flowmeter can be used for lower Reynolds number, choose float with insensitive shape, as long as the Reynolds number at the circulation gap is greater than 40 or 500, the flow coefficient of Reynolds number change will remain constant, that is, the change of fluid viscosity will not affect the flow coefficient. This value is far lower than the minimum Reynolds number of the standard orifice plate and other differential pressure instrument 104-105 requirements.
Most rotor flowmeters do not have upstream straight pipe requirements, or the upstream straight pipe requirements are not high.
Rotary flowmeters have a wide flow range, which is generally 10: 1, the lowest is 5: 1, and the highest is 25: 1. The output of the flow detection element is close to linear. Low pressure loss.
结构简单，价格低廉。 The glass tube rotor flowmeter has a simple structure and a low price. As long as the flow indicator is convenient to use at the scene, the disadvantage is that there is a risk of fragility of the glass tube, especially the non-guided structure float for gas.
Metal tube rotor flowmeters have no risk of rupture of the cone. Compared with the glass tube float flowmeter, the operating temperature and pressure range is wide.
Most structured rotor flowmeters can only be used for pipe installations with vertical flow from bottom to top.
Float flowmeter applications are limited to small and medium pipe diameters. Ordinary full-flow type float flowmeters cannot be used for large pipe diameters. The maximum diameter of glass tube rotor flowmeters is 100mm, and the metal tube float flowmeters are 150mm. meter.
When the fluid used is different from the factory calibration fluid, the flow indication value should be corrected. Rotary flowmeters for liquids are usually calibrated with water, and gases are calibrated with air. If the density and viscosity of the fluid used are different, the flow rate should deviate from the original graduation value and conversion correction should be made.
The rotor flowmeter is an indicator instrument that directly observes the fluid flow in the pipeline through the conical glass tube engraved with a flow scale and the position height of the float in the tube. It is used to measure the flow of one-way media such as non-turbid liquids or gases. It is more convenient and intuitive than other instruments. Therefore, it is widely used in various industrial departments and scientific research units.
在使用安装前，应先检查其技术参数如：测量范围，精确度等级，额定工作压力，温度等参数是否符合使用要求。 Before using the glass rotor flowmeter , check its technical parameters such as: measurement range, accuracy level, rated working pressure, temperature and other parameters that meet the requirements for use. Before installation, the top lining for transportation protection should be removed. And check the cone tube for damage, whether the float can move up and down freely, and it can be installed only after it is normal. The newly installed pipeline should be flushed before the glass rotor flowmeter is installed. The minimum graduation value of the rotor flow meter should be below and installed vertically on the pipeline without vibration. The angle between the center line of the rotor flow meter and the plumb line should not exceed 5 degrees. Large-caliber flowmeters are heavy. To avoid pipe bending, measures such as reinforcement and support can be taken if necessary. It is also necessary to prevent the rotor flowmeter from being subjected to excessive tension, pressure, and torque during installation. So as not to generate excessive external force and damage the tapered tube. According to different working conditions in use, if necessary, a filter should be installed upstream of the rotor flowmeter to prevent contamination by impurities and block the rotor flowmeter. If the fluid is unstable and has a pulsating flow, a buffer can be installed to ensure the good measurement of the rotor flow meter to eliminate the pulsating flow. When the rotor flowmeter is in use, first slowly open the control valve on the upstream pipe of the flowmeter, and then use the regulating valve to adjust the flow rate, so as to avoid the sudden rise of the float to cause damage to the cone tube. In order to ensure the measurement accuracy of the rotor flow meter in use, it is recommended that the common flow rate of the measured fluid be selected to be more than 60% of the upper limit value of the flow rate of the rotor flow meter.