1. Requirements for straight pipe sections
Inlet/outlet straight pipe section: inlet should be ≥10×DN; outlet should be ≥5×DN
2. Grounding point requirement
In order to make the instrument work reliably, improve the measurement accuracy, free from external parasitic potential / the sensor should have good grounding, the grounding resistance is less than 10. (If the metal pipe is well grounded, no special grounding device is required) 3.3 Pair installation Location requirements as shown
Insert the electromagnetic flowmeter according to the situation of the pipeline in the field. If the flowmeter without the ball valve is installed, it should be installed on the pipeline without overpressure (that is, the flowmeter without the ball valve can be installed without pressure), and the hole is opened in the pipeline. Diameter 50, ready to weld the connecting welded pipe to the opening of the pipe; for occasions requiring constant flow loading or unloading or no media spillage, a ball valve must be installed, that is, a plug-in electromagnetic flowmeter with a ball valve structure is selected; With a diameter of 50, it is ready to weld the connecting welded pipe to the opening of the pipe.
Measuring range : Recommended range: 0.5m/s to 10m/s continuously adjustable. Maximum use range: continuously adjustable from 0.2m/s to 15m/s
Signal output: 1, the switch quantity can be set to: pulse output (up to 1000HZ); high/low flow alarm; empty pipe alarm; flow direction indication;
Fault alarm; 2, current output: 4-20mA output
Configuration method: 1. Field configuration through three manual keys. 2. Field configuration via remote control. 3. Perform on-site configuration through the handheld communicator.
Memory: The memory that the EEPROM does not disappear, no battery saving.
Variable area flowmeter (equal pressure drop flowmeter)
The float placed in the upper and lower small tapered flow passages is moved by the force of the fluid flowing from the bottom to the top. When this force is balanced with the "display weight" of the float (the weight of the float itself minus the buoyancy of the fluid it receives), the capture is stationary. The height at which the float is stationary can be used as a measure of the flow rate. Since the cross-sectional area of ??the flowmeter varies with the height of the float, and the pressure difference between the upper and lower parts is equal when the float is stationary, the flowmeter is called a variable area flowmeter or an equal pressure dropmeter. A typical instrument of this type of flow meter is a rotor (float) flow meter.
Momentum flowmeter
A flowmeter weighing flowmeter that uses the momentum of a measuring fluid to reflect the flow rate. Since the momentum P of the flowing fluid is proportional to the density of the fluid and the square of the flow velocity v, i.e., p v2 , when the flow cross section is determined, v is proportional to the volumetric flow rate Q, so p Q2 . Set the proportional coefficient to A, then Q=A. Therefore, P is measured to reflect the flow rate Q. In this type of flowmeter, most of the flowmeters are used to convert momentum into pressure, displacement or force, and then the flow rate is measured. Typical meters for such flow meters are target and rotary wing flow meters.
Some experiences on using ultrasonic flowmeter
1. The flowmeter has two modes, diagonal and reflective. When the reflection mode is not detected, it can be measured in diagonal mode, so that we have been using the reflection mode.
2. The flowmeter requires a relatively high pipe, and the insulation layer must be scraped off, otherwise it cannot be measured. When we measured the air conditioning water system, we cut the insulation layer with a knife to prevent the sensor. After the measurement, the cut insulation layer was glued. The surface of the pipe should be as bright as possible. If it is too rough, it must be sanded.
3. It is difficult to measure when the fluid in the pipeline is not full, so the measuring position should be as straight as possible, away from elbows, valves and other places.
4. The authenticity of the flowmeter reading depends on the signal strength. When the signal is too low, the result is basically unreliable, generally more than 60% or even more.
5. Since the readings may vary greatly, the approach we take is to have the flowmeter read continuously, such as continuously recording one minute of reading and then taking the average.
6. Measuring hot water lines is more difficult than cold water lines. Because the wall temperature of the hot water pipe is high, the coupling agent is easily formed at a high temperature. In addition to the product's own coupling agent, we have tried toothpaste.
The summary of ultrasonic flowmeter measurement accuracy and accuracy needs to be improved.