The field display of electromagnetic flowmeter is 0, with or without empty pipe alarm
The usage rate of electromagnetic flowmeter is relatively frequent. Today, we will introduce some fault analysis and solutions of electromagnetic flowmeter. In general, we should consider several of the most critical causes of failures of the electromagnetic flowmeter. The key points to consider are that the on-site display of the electromagnetic flowmeter is 0, with or without empty pipe alarm, the display of the electromagnetic flowmeter is inaccurate, the current output of the electromagnetic flowmeter is abnormal, and the frequency or pulse output of the electromagnetic flowmeter is abnormal.
First of all, we will analyze that one of the reasons why electromagnetic flowmeter often appears is that the flowmeter field display is 0, with or without empty pipe alarm. Then we need to know about the general situation of the customer, about the caliber of the electromagnetic flowmeter, about the actual flow of the electromagnetic flowmeter on site, about the grounding situation on site, about the type of medium, about the parameter settings of the electromagnetic flowmeter, and about the wiring situation on site.
After understanding the above situations, let’s analyze the caliber of the electromagnetic flowmeter. The caliber of the electromagnetic flowmeter should know the effective range of the flowmeter. Actual flow. To understand the actual flow, it is necessary to know what range the field flow is within the range of the electromagnetic flowmeter. If the grounding condition is not ideal, the flowmeter is easy to generate empty pipe alarm. PVC pipes must be used on site. Use grounding wire to ground. Medium Type Knowing the medium type is to know whether the medium is within the measurable medium of the flowmeter. The conductivity shall be above 5us/cm. Most organics are non-conductive. Parameter setting: whether the air traffic control alarm is set as allowed, and the threshold value of air traffic control alarm. Wiring condition: the electrode wire is disconnected and short circuited with the grounding wire.
Case analysis
Example: An electromagnetic flowmeter has not been used by the user for a period of time. When the flowmeter is reused, the user reported that the flow rate displayed as 0 for a period of time, and an empty pipe alarm occurred. However, one day later, the flowmeter showed flow again, and the customer asked for an explanation.
Need to know the customer
1. Diameter
2. On site flow
3. Grounding
4. Medium
5. Pipeline
1. Diameter
Understand the effective measuring range of flowmeter
2. Actual flow
To know the actual flow, it is necessary to know whether the on-site flow is within the range of the flowmeter
3. Pipeline installation
Understand the length of the straight pipe before and after the flowmeter, the upstream bend of the flowmeter, and the length of the water outlet from the flowmeter
4. Media type
To know what the medium is, it is necessary to know whether there are large particles of non-conductive materials mixed in the medium. If the mixture solution is uneven, it may also shake
5. Whether the vibration of pipeline with or without vibration source will cause flow vibration
6. Whether there is interference source
If there are some high-power electrical appliances on site, such as motor, transformer, water pump frequency converter, they will interfere with the electromagnetic flowmeter.
7. Table body fault
Water entering the meter body may cause the zero point to rise and affect the normal flow display.
After asking the customer, we learned that the customer used an electromagnetic flowmeter with DN100 caliber and was equipped with a 211B converter. The flow used usually is about 80m3/h. The grounding is in good condition. The environment where the flowmeter is used is the printing and dyeing factory, and the main function of the flow is to serve as the cooling water to cool the machine. Through inquiry, we know that most of the fuels and chemicals used in printing and dyeing plants are organic solvents. We know that most of the organic solvents have no conductivity. The printing and dyeing factory will leave most of the organic dyes in the machine due to long time work. From this, we can guess that the concentration of organic matters in the water is very high for a period of time. The low conductivity leads to no flow display and an empty pipe alarm. After a period of time, the organic matter concentration in the water can be detected normally when it decreases.
Solution
It is recommended that the customer set the empty pipe alarm threshold to 2000 and replace the cooling water with new water after a period of use.
Post time: 19-10-22