The mass flow meter is a continuous measurement of the medium’s flow rate. The sizes are in weight engineering units such as kilograms or tonnes.
The mass flow meter is not able to control the flow rate. It can only detect the mass flow of liquids or gases. We output the flow rate value using analog voltage, current or serial communication. However, mass flow controllers are instruments that can both detect and control.
1. Mass Flow Meters Need to Ensure Quality
With the continuous popularity of the mass flow meter, there are more and more relevant manufacturers in the market. Therefore, many people will blindly order. If you buy a quality flowmeter that is not up to scratch, then naturally, in the measurement is easy to produce inaccurate results. Therefore, to ensure that the measurement task is carried out properly, you must ensure that the quality of the mass flow meter purchased is up to scratch. When purchasing, the need to choose the formal purchase channels while screening the manufacturer’s qualifications, reputation, etc.
2. Always Pay Attention to the Flowmeter Changes
In the measurement process, there may be some situations. For example, when the medium has the problem of air entrapment, it may lead to sensor failure or trigger the pain of transmitter failure. Therefore, the mass flow meter should pay attention to observation if a failure alarm should immediately stop measuring.
3. How are Mass Flow Meters Installed?
3.1 Why Do General Flow Meters Need Straight Pipe Sections?
A sufficiently long straight section of the pipe allows the flow pattern of the medium to be fully extended. The velocity flowmeter gives a stable flow field and improves the measurement accuracy.
For some flow meters with many mechanical components, a straight section reduces the impact of sudden changes in the flow pattern and extends the service life. For example, some velocity meters require linear upstream areas up to 40 times.
3.2 Why Do Mass Flow Meters Not Require a Straight Pipe Section?
All flow meters based on flow rate have a specific straight section requirement to bring the meter’s metering conditions close to the laboratory calibration.
Due to the influence of pipe flanges, reductions, expansions, rectifiers, elbows, and valves on the fluid. Therefore, we can eliminate the need for straight pipe sections when the mass flow meter does not have any relationship to the flow rate of the medium.
3.3 Mass Flow Meter Installation Location
- Easy to view data.
- Easy to maintain daily.
- Out of direct sunlight.
- Avoid vibration.
- Ambient temperature as required.
- Keep away from electromagnetic solid interference devices.
3.4 Sensor Mounting Orientation
3.5 Sensor Piping Installation
- Avoid twisting/bending stresses.
- Don’t use sensor alignment lines.
- Don’t use sensor support lines.
- Don’t support directly on the sensor.
- Downstream valve for zeroing.
- Elbow to avoid condensation entering the junction box.
- Maximum cable limit between sensor and transmitter 1000ft (300m).
- minimum distance of 0.6m between the sensor and giant transmitter or motor. As the sensor relies on electromagnetic fields for its operation, it is essential to avoid installing the sensor near large interfering electromagnetic fields.
- Choose installation locations to avoid vibrations as far as possible.
3.6 Further Considerations for Installation.
3.6.1 Shut-off and Control Valves
To ensure that there is no flow during zeroing, shut-off valves are installed upstream and downstream of the mass flow meter and are leak-free.
The control valve should be installed downstream of the mass flow meter, and the mass flow meter should be kept at the highest possible static pressure to prevent cavitation and flashover.
3.6.2 Pulsation and Vibration
To prevent external mechanical vibrations from occurring in the process, we should ask the manufacturer for the resonance frequency range of the supplied mass flow meter; the manufacturer can also be provided with the vibration conditions on site and then consulted as to whether the following measures are required, e.g.
- The installation of pulsation attenuators
- Vibration attenuators or flexible connection tubes.
- Special clamping devices for flow sensors, etc.
3.6.3 Prevent the Interaction of Mass Flow Meters
In the same type of two mass flowmeter series installation or more than one mass flowmeter close to the ground in parallel (or parallel) installation. Especially when installed in the same support frame, the measurement tube vibration will make the mass flowmeter between each other, resulting in interference and causing abnormal vibration. In severe cases, the instrument can not work.
3.7 Installation Should Take Precautions
- To the manufacturer proposed staggered close to the resonance frequency value of the instrument.
- Pull away from the flow sensor distance, not set on the same pedestal, independently set up support frame.
- Install the flow sensor in a different direction.
Set up vibration-proof material isolation between flow sensors and other methods.
3.8 Loading and Unloading Metering.
The sensor housing should be mounted upwards or vertically in loading and unloading metering applications. In addition, a check valve should be installed downstream of the sensor to prevent the backflow of the media.
The check valve should be installed as close to the sensor as possible. Sometimes, the process medium cannot be completely removed from the pipeline, and flag mounting is generally recommended.
3.9 Steps for loading or unloading
When loading or unloading the application, we should try to follow the following driving steps.
Install the shut-off valves upstream and downstream of the sensor.
- Close the upstream valve.
- Open the downstream valve partially.
- Slowly open the upstream valve to expel air and fill the sensor with the medium.
- When the flow system starts metering, slowly open the downstream valve until it is fully open.
4. Mass Flow Meter Construction Attention?
If for a new pipeline, we install the sensor after the blowdown process (or if there is a blowdown subline and the hand valves before and after the flowmeter are cut dead during the blowdown).
In the pipeline into the line welding operations, remove the sensor. When installing large diameter sensors, do not support the support on the sensor housing.
① To check the pipe, remove the flange fasteners from the flange on one side. Next, remove the pins from both sides of the support and see if they are aligned. If they are out of alignment, calibrate them.
② The installation position is too high.
③ The installation position is too narrow.
④ The Flowmeter sensor connected to the opposite flange does not match.
⑤ The flow meter is installed at the end of the discharge downwards, as shown in the diagram below (liquid way, gas the opposite.)
⑥ The connection cable is threaded into the meter from the bottom to the top.
⑦ Water is fed from inside the pipeline.
⑧ We can use a steel ruler or angle ruler against both sides of the flange to detect concentricity deviations of ≤ 0.5mm.
5. Conclusion
The mass flow meter is a meter that is currently attracting a lot of attention. It has many advantages such as accurate measurement, simple operation, and reasonable price. But to perform properly, you must learn to use the mass flow meter correctly.
