Glass rotor flowmeter

Glass rotor flowmeter

The main measuring components of a glass rotor flowmeter are a vertically installed lower small upper large conical glass tube and a float that can move up and down inside. When the fluid passes through the conical glass tube from bottom to top, a pressure difference is generated between the upper and lower parts of the float, and the float rises under this pressure difference. When the upward force, buoyancy, and viscous lift acting on the float are equal to its gravity, the float is in an equilibrium position. Therefore, there is a certain proportional relationship between the fluid flow rate flowing through the glass rotor flowmeter and the rising height of the float, that is, the flow area of the glass rotor flowmeter. The position height of the float can be used as a measure of flow rate.

How to choose a glass rotor flowmeter correctly?

Types and selection of glass rotor flow meters
Glass rotor flow meters can be divided into eight series based on their applications and adaptability: ordinary type, reinforced pipe type, small flow and small shape type, corrosion-resistant type, laboratory type, insulation type, alarm type, and high-pressure resistant type. According to the national instrument series spectrum, regardless of which series, there are a maximum of 12 calibers ranging from 1 millimeter to 100 millimeters. The measurable flow range is: 0.1 milliliter/minute to 40 cubic meters/hour for liquids (water) and 1 milliliter/minute to 1000 cubic meters/hour for gases (air). The glass rotor flowmeter used for environmental protection instruments generally has a diameter of no more than 10 millimeters, and the measured flow rate belongs to the small flow range.
Calibration correction of glass rotor flowmeter
The scale of the glass rotor flowmeter is calibrated by the manufacturer using water and dry air, which are close to ideal fluids, as the medium under local conditions. But in the use of flow meters, there are two situations where their scale values cannot be directly used: one is when the measuring medium is not water and air, and the other is when the measuring medium is water and air, but its state (temperature, pressure) is different from the scale state. In this way, when using a flow meter, there is a problem of needing to correct the scale values in order to obtain accurate measurement results. Therefore, solving the calibration correction of glass rotor flow meters is the key to using this type of instrument effectively.
Considering the extensive use of rotor flow meters in environmental instruments for measuring gas medium flow, the following discussion will only focus on density correction during gas medium measurement. Due to the low viscosity of gas media, the influence of viscosity is omitted in the discussion. Practice has proven that this does not affect the accuracy after correction.