Advantages of Rotameter :
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. Suitable for measuring low flow rate and small flow rate, taking liquid as an example, the nominal pipe diameter of glass tube rotor flowmeter full-scale flow rate below 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 type instruments 1 × 104 ~ 1 × 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.
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 is only suitable for gas. Metal tube rotor flowmeters have no risk of rupture of the cone. Compared with glass tube rotor flowmeters , 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.
Disadvantages of rotor flowmeters :
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.
Rotor flowmeter applications are limited to small and medium pipe diameters. Ordinary full-flow type rotor flowmeters cannot be used for large pipe diameters. The maximum diameter of glass tube rotor flowmeters is 100mm, and the metal tube rotor flowmeters are generally 150mm. For larger tube diameters, only shunting Instrumentation.