Tips of using the metal tube variable area flowmeter
Author:vacorda Source:vacorda.com Date: 2016-12-29 15:47:36
Metal tube rotameter variable area flowmeter is one of the variable area flow meter, and it is most commonly used in the industrial and laboratory, and it has the characteristics of simple structure, intuitive, small pressure loss, easy maintenance and so on. Here, we will provide you some tips about using this type of variable area flow meter.
1. Installation direction of the flow instruments
There are two types of the installation, horizontal and vertical installation.
2. For dirty fluid installation
The filter should be installed upstream of the flowmeter. When magnetically Coupled Metal Tube flow flowmeter applications for the fluid with magnetically-impulisable, it should be installed a magnetic filter in front of the meter. And need to maintain the float and cone cleaning, especially small-diameter flow instruments, float cleanliness significantly affect the measured accuracy.
3. Pulsating flow installation
The pulsation of the fluid itself, if there are reciprocating pump or regulating valve in the upstream position of the instrument, or downstream of a large load changes, etc., should change the measurement position or remedy improvements in the pipeline system, such as the installation of buffer tank; If the instrument itself oscillation, such as gas pressure is too low when measuring, the instrument upstream valve is not fully open, the regulator valve is not installed in the instrument downstream or other reasons, should be targeted to overcome, or choose the instrument with a damping device.
4. Expanded range of installations
If the measured flow range is wide, and over 10, you can put in to two different shapes and weight of the float in a single instrument, when small flow, take the value of the light float, after the float up to the top, taking the value of the heavy float, the range of degrees can expanded to 50-100.
5. To drain all the gas in the liquid used instrument
The inlet and outlet of the metal float flowmeter is non-linear angle, when used to liquid, it need to pay the attention to the gas is all drained in the casing of the outside float the displacement; If the liquid contains tiny bubbles, when the liquid flow, it is easy to accumulate in the casing, this is more important for small diameter instruments, otherwise it will effect the flow accuracy.
6. flow value need to do the necessary conversion
If the flow instrument is not produced by the actual density, viscosity and other media parameters, the liquid instrument is usually demarcated with water, gas meter with air calibration, fixed value in the engineering standard state. When the use of the conditions of the fluid density, gas pressure and temperature is not the same as the calibration value, it need to do the necessary conversion. And the conversion formula and method always conclude in the manufacturer's instructions.
7. Calibration of the float rotameter
As to the calibration of the float flowmeter, generally, the standard table method, volumetric method and weighing method for liquids; for gas commonly used the bell method, small flow with soap film method. Some foreign manufacturers of bulk products have been using the dry calibration method, that is, control the size of cone-shaped tube and float weight and size, indirectly determine the flow value, in order to reduce costs, only for the high-precision instruments will do real flow calibration. The instrumentation manufacturers , including the conical tubes and floaters of these are interchangeable and do not require complete replacement. The standard table method of calibrating the float flowmeter is a high efficiency method.