Level switches for monitoring central lubrication systems
In central lubrication systems such as single-line systems or progressive lubrication systems, a whole range of peripheral components are used to monitor the functions of the system. Thermodynamic variables such as volume flow, pressure, temperature and others must be continuously measured and monitored to ensure proper lubrication of the system.
One of the central monitoring tasks in central lubrication systems is performed by the level switch, which is responsible for checking the level in the unpressurized lubricant containers. The reservoir represents the container of lubricant in central systems and is essential for continuous lubrication of the system. The fill level monitoring is responsible for sending a signal to the operator of the system if the maximum value is exceeded or falling below the minimum value or initiating the automatic refilling of the container. The signal can be generated, for example, with a float switch or a liquid level switch. Some switch systems are even able to issue an early warning before the reservoir is at a minimum level.
Technical background for level monitoring in central lubrication systems
Depending on the intended use, different types of level switches can be used to monitor the level in lubricant containers. A basic distinction is made between switches for horizontal or vertical installation.
The level switches with horizontal installation position include, for example, the models WS63 and WS68 from SKF. Both variants are suitable for lubricants with a maximum effective viscosity of 1,500 mm/s². If the viscosity is higher than this limit value, inaccuracies in the monitoring result due to shear forces. Each of the level switches has a switching point. This means that a signal is issued as soon as the minimum fill level in the lubricant reservoir has been reached. While the WS 68 is used at temperatures between +5 and +60°C, the sister model WS 63 is even suitable for a range from -10 to +60°C.
If you use oil in a central lubrication system in connection with a pump unit of the type MKx, the vertical level switch of type 175-210-01x is recommended. This also has a switching point for the minimum level and works with a magnetically operated reed contact for signal transmission. With regard to the type of function, you can choose between two versions of the float switch. The difference is that the contact is either opened or closed when the minimum fill level is reached.
Model 995-001-901 is also installed vertically and used to monitor MKx systems. It is suitable for central lubrication systems with fluid grease and covers a temperature range from -25 to +80°C. The contact of the float switch opens when the level in the tank is too low.
The models in the WS32-x, WS33-x and WS35-x series are used for liquids with a maximum viscosity of 1,500 mm²/s and are equipped with either device or circular plugs. The WS35-x level switch even has two different switching points. As usual, one switching point is responsible for monitoring the minimum level in the container, while the other point generates a warning when there is a remaining amount of approx. 25 mm. All three float switches are installed in a vertical position.