Selection of liquid level control system for accident water towers in steel mills
Thread Content
Level control of the accident water tower is extremely important. During construction, I ran an 8-core control cable (not a shielded cable) from the control room, through the power cable trench, to the top of the water tower. Due to the long length of this cable, using analog signals for measurement and feedback would inevitably lead to interference. It’s not feasible to run a new cable, so I had to opt for digital level control based on the existing conditions. Which reliable and practical model of level controller should be chosen?
This post was last edited by zhaohh3211 on 2010-10-19 08:32. Why not simply use a high-level float switch or a pressure switch? Analog values are programmable and offer a high number of segments, but it’s not as satisfying as digital signals. Your goal is simple: to maintain a certain level of water in the water tower, so that the pump can supply water automatically. An eight-core cable is sufficient to install one pressure switch each for the high, medium, and low positions.
There are many types of liquid level controllers; just using one of them proves to be unreliable, as it occasionally sends false signals. So there is a fear of misleading the workers on the job and causing production accidents. Based on the site conditions, I think I should use a power supply of 220V; a 220V digital signal feedback will be sufficient. However, I’m not sure which manufacturer’s models are reliable. Who has some samples? Please help me choose.
This post was last edited by zhaohh3211 on 2010-9-6 at 12:14. If you must use 220V, it is recommended to use direct-current 220V.
Thank you, big bro! Is there a specific model for this type of equipment?
This post was last edited by zhaohh3211 on 2010-10-19 08:33. To be honest, I don’t know much about instruments, but I work with them quite often. If you want to ask questions about this topic, go to the instrumentation area – there are professionals in that field, while those in this electrical area only have a basic understanding.
By using a float switch or pressure switch directly to detect high and low liquid levels, with a voltage of 220V DC, reliability is very high and the cost is low. For such a simple control mechanism, is it really necessary to purchase a dedicated level controller?
This post was last edited by zhaohh3211 on 2010-10-19 08:34. Using a pressure transmitter makes it less likely to occur measurement errors, as this can be achieved simply by adjusting the range. The problems that used to occur with the pressure switches during repairs can be reduced in this way.
This post was last edited by zhaohh3211 on 2010-9-2 07:50. If your water tower in question is an empty tower, it is recommended that you use a cable float level switch. With the right selection regarding the material of the float, cable, and flanges, this type of switch performs better than other types of level switches, and it is also cost-effective; however, its control accuracy is not very high.
In that case, a special type of cable similar to crane cables should be used!
A rod-type level switch is cheaper and also very reliable; I saw such switches being used for controlling the water level in dust collectors at power plants. There are 4 different level settings, and they can be installed directly. Given that your water tower is quite tall, it should be fine to install them at various levels. I just can’t remember what the voltage rating is; a relay is necessary, as it’s not a simple conductive switch.