Thread Content
As a precision measuring instrument, the mass flow meter has very high installation requirements. During installation, it is first necessary to determine the installation location; when installing the sensor, it is important to protect it from damage. Vibration reduction also needs to be properly addressed; of course, there are some other considerations as well, which are detailed in the articles below. I. Installation location of the mass flow meter 1) The installation location should be far away from sources of interference that can cause mechanical vibrations in the pipeline, such as pumps on the process pipelines. If sensors are used in series on the same pipeline, special care must be taken to prevent mutual interference caused by resonance; the distance between sensors should be at least three times the width of the sensor’s physical dimensions. 2) The installation location of the sensor should take into account the expansion and deformation of the process pipeline due to temperature changes; in particular, it must not be installed near the expansion joints of the process pipeline. If installed near an expansion joint, the expansion and contraction of the pipeline will generate lateral stress, causing a change in the sensor’s zero point and affecting measurement accuracy. 3) The sensor should be installed away from sources of industrial electromagnetic interference, such as high-power motors and transformers; otherwise, the natural resonant vibrations of the measuring tube in the sensor will be disturbed, and the weak signals detected by the speed sensor may be overwhelmed by the noise caused by electromagnetic interference. Sensors should be placed at a distance of at least 5 meters away from transformers and motors. 4) The sensor should be installed in such a position that the fluid within the pipeline always fills the sensor’s measuring tube, with a certain pressure buildup; this requires that the installation location be at the lower end of the pipeline. II. Selection of the installation method for mass flow meter sensors The installation method of the sensor is determined primarily based on the phase of the fluid and the conditions of the process; there are three such installation methods. 1) Horizontal installation with the main body facing downward: When the fluid to be measured is a liquid, it is common to install the sensor with its casing facing downward, in order to prevent air from accumulating inside the sensor’s vibration tube and thus ensure accurate measurement of mass flow rate. 2) Horizontal installation with the main body facing upward: If the fluid to be measured is a gas, it is usual to install the sensor with its casing facing upward, to avoid the accumulation of condensation inside the sensor’s vibration tube. 3) Flag installation: If the fluid under test is a mixed slurry of liquids and solids, the sensor should be installed in a vertical pipe; this prevents particles from accumulating inside the sensor’s Coriolis force measurement tube. Furthermore, if the process pipeline needs to be cleaned with gas and steam, this installation method also facilitates cleaning; however, it is more difficult to secure than the first two methods, and it results in higher pressure losses. III. Other precautions during installation 1) Before installing the sensor on the process pipeline, it is necessary to first verify that the DC resistance of the sensor’s speed sensor coil and drive coil, as well as the resistance value of the platinum resistor thermometer, are within normal ranges. 2) The sensor mounting flange must be connected coaxially with the pipeline flange in order to reduce installation stress and ensure measurement accuracy. During installation, it must be ensured that the pipeline supports hold only the process pipelines; it is prohibited to use sensors to support the process pipelines. The sensor housing must be kept suspended, without touching any objects. 3) When installing the sensor on the process pipeline, it is necessary to ensure that the pipeline system is firmly connected to stable supports at two positions upstream and two positions downstream of the sensor; all threaded connections must be tightened, and clamping the process pipeline helps to reduce potential vibration disturbances. 4) During installation, avoid moving the sensor by using its housing. 5) Valves or pumps located on the process piping near the sensor installation location must have their own supports; the supports used for the sensors cannot be used to support these valves and pumps. 6) Shut-off valves should be installed upstream and downstream of the sensor. 7) Eliminate installation stress: When installing sensors, the most effective way to eliminate installation stress is to first lay the piping, pre-installing the process pipelines and valves along with the sensors, then lift them into place and weld them to the main process pipeline. To achieve the best stress-relief effect, the sensor, shut-off valve, and main process pipeline should all be in the same vertical plane. 4. Vibration reduction: 1) When installing the sensor, it is necessary to choose an appropriate location for it; in addition to keeping it away from sources of vibration, support rods should also be used to firmly support the pipes and valves in order to eliminate the impact of vibrations on measurements. The lower end of the support rod must be fixed to a stable base, while its upper end works in conjunction with pipe clamps to support the process pipeline. Never use the sensor housing to support the sensor, as well as pipelines, valves, pumps, etc. 2) After the sensor is installed, its housing should be in a freely suspended state. For the installation methods: (1) horizontal installation with the main body facing downward, and (2) horizontal installation with the main body facing upward, the support rods should be symmetrically distributed around the sensor. For installation method (3) – flag installation – the choice of support pivot point depends on the specific circumstances. If the lower end of the support rod is to be fixed to the ground, it must be a concrete and rebar foundation, in order to provide stability for the support while also serving to reduce vibration. The more stable the foundation, the better its vibration damping capacity.