Level switches play an important role in level control. The main types of level switches are Float Level Switches, Tuning Fork Level Switches, Rotary Paddle Level Switches, and Ultrasonic Level Switches.
This article will cover installation considerations for each type of level switch. The following recommendations are for reference only. We recommend that the installation be carried out in accordance with the operating instructions provided by the supplier. Professional help can be sought when necessary.
Float Level Switch Installation
Float level switches work based on the magnetic coupling principle. When the liquid level of the controlled liquid reaches the set value, the Float Level Switch sends out a corresponding switching signal to control the liquid level. Float level switches can be used with corresponding external circuits or DCS, PLC systems. It can realize remote alarm and control of the liquid level.
Nowadays, the switching devices are more convenient. The installation of a float level switch is relatively complicated:
1. The installation position should be away from the water inlet. Otherwise, the switch will cause false operation due to the fluctuation of the water inlet.
2. If the switch device is in the wall of the vessel pool, it can be installed with an L-type angle bracket.
3. If the switch device is located in the mixing area, a wave-proof tube or wave-proof baffle can be installed.
4. The inner diameter of the selected pipe should be larger than the diameter of the float flange connection pipe.
5. Wiring is recommended to use a multi-piston cable.
6. The load of the controlled line must be matched with the contact capacity of the float switch.
7. The specific gravity of the measured liquid must be greater than the specific gravity of the float.
8. The action point of the float has been adjusted at the factory according to the customer’s ordering requirements. So please do not adjust the float position at will.
Tuning Fork Switch Installation
Tuning Fork Level Switch is a special level control instrument for vessels, tanks and various pipelines. Different installation methods are available for different working conditions. In order to enable users to install tuning fork level switches correctly, the installation of tuning fork level switches and the precautions are introduced as follows.
1. Instructions before installation
Before installation, please reconfirm whether the instrument model of the tuning fork liquid level switch meets the requirements of the working conditions on site. Such as: process pressure, process temperature, chemical properties of the medium, etc.
It is important to ensure that the instrument can be used normally after installation.
2. Method of installation
There are three kinds of mounting methods for tuning fork level switches: threaded, flange and clamp mounting. We need to determine which mounting method to use according to the tank structure.
3. Installation direction
Generally speaking, the tuning fork level switch can be installed in any position as required. There are three types of mounting methods for tuning fork level switches: horizontal mounting, vertical mounting and inclined mounting.
When installing the tuning fork level switch, the fork face and the liquid lift or flow should be kept in the same direction. However, when the measured medium is viscous, the instrument should be installed vertically to avoid the phenomenon of material hanging.
To avoid hanging material or measurement error due to the resistance of the medium to the fork body. Please refer to the following figure for installation.
① Marking point of threaded connection ② Medium flow direction.
4. Installation should avoid the feeding port
The probe is the key component of the level switch. When choosing the installation position of the tuning fork level switch, attention should be paid to avoiding the feeding port for installation. Because the installation in the feeding port position is likely to cause measurement errors or even damage to the instrument.
5. Installed in a pressure/vacuum environment
For over-pressure or under-pressure or even vacuum environments, the sealing integrity of the process connection must be ensured. Before installation, make sure the sealing material meets the requirements of process temperature and process pressure.
6. Do a good job of moisture-proof measures
If it rains or there is condensation, rain and condensate will flow down with it. Therefore, before connecting the cable, please bend the cable and lead it downward to prevent water or moisture from entering the instrument, as shown in the following figure.
Ultrasonic Level Switch Installation
Ultrasonic level switches are suitable for almost most applications due to their own advantages. For crude oil storage tanks and liquid hydrocarbon storage tanks, ultrasonic level switches are the best choice. However, the cost of ultrasonic level switches is high. So for atmospheric product storage tanks, the choice of tuning fork level switches is safer, more reliable and economical.
1. The basic principle of instrument and probe installation
(1) When the product is installed, it should be equipped with a cable introduction device that has obtained an explosion-proof certificate and the explosion-proof mark is ExdIIC Gb. And the protection level is not less than IP67. And the assembly should ensure that the explosion-proof thread connection dimensions are in accordance with the provisions of GB3836.2-2010.
(2) Please do not use other ultrasonic equipment or electromagnetic equipment in the vicinity. so as not to cause the instrument to operate incorrectly due to mutual interference of the equipment;
(3） The two probes of the double probe level controller must be arranged horizontally on the tank wall;
(4) There should be no weld between the two probes, and the position of each probe should be far away from the weld.
2. Probe installation process on the tank
(1) For ferromagnetic tanks, just use the magnetic adsorption method to adsorb the suction cup directly to the vessel wall.
(2) For non-ferromagnetic glass, stainless steel and other materials, they can be used to glue or bracket fixing, welding and other ways to fix the probe on the outside of the container wall can choose other installation methods.
Take the magnetic adsorption method as an example, the probe installation process is as follows:
a. Select the monitoring position on the tank wall;
b. Handle the installation joint surface: clean out two planes of about 120mm long and 90mm wide on the tank (the spacing between the two planes is arranged horizontally according to the actual probe spacing size). So that the joint surface of the probe is as flat and smooth as possible.
If there is an insulation layer on the tank wall, the insulation layer should be cleaned up and removed from the middle rectangular area. To ensure that there is no weld in the middle of the two probe positions!
c. Probe Installation: Apply a layer of silicone grease uniformly on the probe sensing surface and the tank wall mounting joint surface. Note: Apply a moderate amount, thin and even.
① Make sure that the waterproof pad around the probe is filled tightly, flat. So that the curved flow-guiding groove opens down, the probe and the seat of the whole adsorption in the tank wall. Do not rotate, shaking so as not to squeeze off the silicone coupling probe badly;
② probe 1 and probe 2 installation method is the same. To ensure that the two probes are at the same level, and the spacing range of the actual distance between the probes;
③ The two probes are installed in the direction of: If the tank is a small pipe diameter, please follow the conventional ③ Installation direction of the two probes: if the tank is a small diameter, please install according to the general direction in the following figure. When the tank diameter is large, it is recommended to rotate the two probe seats respectively 90 degrees to install.
Installation and fixation of the probe to the installation of the joint surface coated with silicone grease to deal with the installation of the joint surface.
Selection of the installation position of the external ultrasonic liquid level controller User’s Manual.
④ Probe installation and debugging is completed; it is recommended to fill the probe seat surrounded by glass adhesive on the overall sealing of the probe to ensure that the rain will not be installed to wash away the ultrasonic probe front surface. Silicone grease applied on the front surface of the ultrasonic probe!
Note: After the probe is adsorbed and installed, try not to collide and move it again, so as not to accidentally pull the probe to slip, vibration and affect the measurement accuracy of the liquid level controller.
Rotary Paddle Level Switches Installation
The Rotary Paddle Level Switch is the most widely used level switch. It is the ideal level controller for solid particles and powder materials. It has a wide range of applications in modern industrial processes and warehousing sectors.
The Rotary Paddle Level Switch utilizes a miniature motor as the drive unit, with the drive shaft connected to a clutch. When not in contact with the material, the motor operates normally. When the blade touches the material, the motor stops rotating and cuts off the power supply by itself. And at the same time, the detection device outputs a contact signal to control the material transportation.
Rotary paddle level switch can be widely used in mining, chemical, beverage, cement, plastic, chemical fiber industry, powder, granules and other solid materials. In specific applications, special attention should be paid to the installation position. For different working conditions, selecting the optimal installation position can significantly extend the product’s service life. while avoiding false alarms.
When installing the rotary material level switch, generally pay attention to the following points:
1. Before installation, please confirm whether the power supply voltage is the same as the voltage above the sign.
2. Confirm the density of the measured material and choose the best blade shape and size. Generally, the higher the density, the smaller the blade.
3. Confirm whether to install horizontally or vertically before installation:
I. When installing horizontally, install the blades at an angle of 10-20° from the horizontal downwards. To reduce the impact of materials.
II. When installed horizontally, the junction box inlet should be vertically facing down. The cable fixing nut must be locked, and a rain cover can be added if necessary.
4. It should be avoided from being installed in the material inlet part. When it can’t be avoided, it can be installed protection baffle plate at 200mm above the switch to protect the blade from the impact of the material.
5. Do not knock the transmission part and the blade part when installing the product. So as not to cause unnecessary damage.
Sino-Inst Featured Level Switch
Level Switch Maintenance
Level switches and other instruments are widely used. Especially in extreme environments where they can also be found. Therefore, in order to make the level switch work stably for a long time. It is indispensable to maintain these instruments in daily work. According to the working conditions and the nature of the level switch, we should pay attention to the following points for the maintenance and repair of the level switch:
1. Maintenance and maintenance should be targeted
Different instruments have different characteristics. Therefore, our level switch maintenance and maintenance requirements are not the same. Such as whether contact with corrosive media, there is no mechanical wear and tear, what load, etc. To take appropriate maintenance measures, one can not take a one-size-fits-all approach. Otherwise, both increase the cost, but also can not play a proper protective role. ”
2. Pay attention to where the instrument is installed in the appropriate location
Different installation positions have a great influence on the accuracy of level switch measurement and service life. Generally speaking, if the instrument can be installed indoors, it should not be installed outdoors. If it can be installed in a cool and dry place, it should not be exposed to sunlight or installed in a dark and humid place. A level switch is best not to be installed in extreme environments.
3. Good level switch maintenance.
Generally speaking, before purchasing, you should choose the level switch structure with better protective materials, protective layer process and level switch. However, in the later maintenance, we need to take into account the material, protective layer process and structure of the three aspects.
Generally speaking, the selection of protective materials and protective layers should be determined according to the degree of permissible erosion of the instrument.
Since the absolute non-erosion of the material and maintenance and maintenance layer does not exist. In many chemical equipment, the corrosion of the metal is not more than 1mm per year to meet the requirements. Level switch protection requires that the corrosion resistance of the metal be controlled to a certain rate per year.
Like the meter head of some level switches, some components are exposed and are very easy to be damaged by erosion. But the meter head of Sino-Inst is designed in an encapsulated form, which has a high protection level. Therefore, when purchasing Level switches, give priority to meters with protective materials, protective layers and a reasonable meter structure design.
4. Pay attention to the correct protection method
In order to ensure the accuracy of the level switch, try not to use isolators or other isolation devices to protect the level switch. If compelled to, must also pay attention to careful selection, to determine the isolation fluid, and the correct choice of isolation membrane.
If the level switch is susceptible to medium impact damage, you can take the addition of protective baffles or niche installation for protection.
5. Do a good job of level switch labeling and other parts of the maintenance and maintenance
The nameplate of the liquid level switch generally records the specification model of the instrument, the scope of use and so on. It is indispensable for the installation, use and maintenance personnel of the instrument. Therefore, in the daily maintenance process, one must pay attention to do a good job in the instrument labeling and other parts of the maintenance and maintenance work.
Why are there three wires on a float switch?
1. Float level switches are generally three-wire. There is a public line, and the other two wires are to control the induction of high and low level. Equivalent to a ball with two switch points and three wires. A normally open, a normally closed.
2, generally 3 lines, black line public, normally open (brown), normally closed (blue), different manufacturers may be different colors. It is best to use a multimeter to measure, respectively, arbitrarily selected 2 of them. shake the float to simulate the float action, to find the public line, so you can know the other 2 a normally open and normally closed.
What are the disadvantages of a float switch?
1. The measurement accuracy is limited:
The measurement accuracy is affected by the volume of the float, magnetic switch sensitivity and other factors. Generally can only realize rough level measurement. In the need for high-precision measurement occasions. such as precision chemicals, pharmaceuticals, etc., may not be able to meet the requirements.
2. susceptible to contamination:
The float may be contaminated after a long time running in the liquid. Affect the buoyancy of the float and the sensitivity of the magnetic switch. This results in increased measurement error. Especially in the liquid containing impurities, particles, it is more likely to have such problems.
3. Limited installation:
The installation position and mode of the float switch level meter are limited by the shape and structure of the container. In some special shape of the container, it may not be able to find a suitable installation position.
4. Maintenance cost:
Although the structure of the float switch level meter is simple, it still needs regular inspection and maintenance after long-term use. Such as float, rod, and other parts of the cleaning, replacement, etc., all need certain maintenance costs.
What is the lifespan of a float switch?
The lifespan of a float level switch is about 1-5 years. Its lifespan is affected by the material used, the liquid environment, the ambient temperature and pressure, and so on.
In short, the installation of a switch does not allow any deviation. Because correct installation means high measurement accuracy and long service time. I believe that after reading the above article. You have learned the methods of the relevant level switch installation.
If you still have related technical questions, please feel free to contact Sino-Inst. We are a level switch supplier from China. Our level switches are of good quality and cost-effective.
