About the Four Tank System


Pictured here is a labeled diagram of the Four-Tank System.

Labeled 4-Tank System
Legend

Setup

  • All tanks have an electric level sensor installed at the bottom
  • Manual as well as automatic controls are placed to control tank flow
  • Tank 4 is connected to Tank 1, as Tank 2 is to Tank 3.
  • PLC interfaces between HMI and Valves

The Process

When execution begins, the operator of the HMI will set a level for the lower tanks to be at (4 inches, 3 inches, etc.,) as well as input a value between 0 and 100 to regulate the position of the system valves. The values of the two tank levels or valve positions do not have to be the same.

Once the process is started, the pump and flow control valve on the left will circulate water into the system. The tank control valve will begin to distribute water into Tank 2 to meet the level input by the operator. At the bottom of Tank 2 there is a manual valve that allows water to drain into the tank below. Once the sensor informs the PLC that it has met the designated level, the tank control valve will switch and begin distributing water to Tank 3. As Tank 3 fills with water, it will drain into Tank 4. The same process applies to Tanks 4 and 1, where Tank 1 will drain into Tank 2. 

Through this setup, an interconnected system is created that will effectively work against itself in order to maintain proper lower tank levels.