The Velleman K2639 Liquid Level Controller is a versatile and reliable instrument for controlling the level of various liquids such as water, oil, and other fluids. The controller can be used for industrial and home applications for the purpose of switching on/off pumps, controlling heaters, etc. It features an adjustable delay time of 1 to 999 seconds, and can be used for controlling up to 2 valves, which allows for simultaneous liquid level control. The controller comes with two 1/2" BSP threaded ports for connection to valves, and can also be used for connecting to various accessories such as pressure sensors or float switches. Additionally, the unit is certified to EN61000-6-1 and EN61000-6-2, and is RoHS compliant.