The pressure switch - indispensable in central lubrication systems
Pressure switches are used in central lubrication systems such as single-line systems to monitor the pressure in the system and to ensure proper lubrication. The main task of the pressure switch is to monitor the intermittent build-up and release of pressure in the single line pump. In central lubrication systems, the single-line pump is responsible for ensuring that the oil or grease is conveyed from a container to the metering device and from there to the assigned lubrication points at a defined pressure. Due to the constantly changing pressure build-up in intermittent single-line systems, the pressure switch has an important task.
In addition to the monitoring function, pressure switches such as the models DS-W20-4, DS-W12-4 or 176-112-000 are responsible for ensuring that the pressure relief in the MonoFlex central lubrication system works properly and that the function of the lubricant metering device is guaranteed. The correctness of the directional control valves, the detection of breaks in the line and the functionality of the filters can also be monitored using pressure switches.
Technical details on pressure switches
Pressure switches such as the models DS-W20-4, DS-W12-4 or 176-112-000 from SKF monitor the pressure in the central single-line system and send out signals at certain, predetermined pressures. These signals can be used, for example, to monitor the runtime of the single-line pump specified by the system and the pressure relief in the main line.
Depending on the type, pressure switches can be used for different lubricants. The spectrum in the SKF model series ranges from oils and greases of NLGI classes 000, 00 and 0 to greases including NLGI class 2 to oiled compressed air and air. With regard to the design, a distinction is essentially made between the three types of break contacts, make contacts and changeover contacts.
Advantages of pressure switches in single-line systems
Single-line systems are used in a wide variety of systems and machines to compensate for the loss of lubricant due to evaporation and aging. The lubricant is supplied intermittently at machine cycle or time-dependent intervals. One of the main advantages of central single-line lubrication systems is the simple monitoring and ensuring their correct functionality. Pressure switches take over this function and ensure smooth operation of the system. Areas of application include machine tools, machining centers, compressors, wind turbines and packaging machines.
The models DS-W20-4, DS-W12-4 or 176-112-000 from SKF
SKF type DS-W20-4 and DS-W12-4 pressure switches are used in single-line lubrication systems with maximum operating pressures of 45 bar. The two models differ in terms of the nominal switching pressure, which is 20 bar for the DS-W20-4 and 12 bar for the DS-W12-4. Both types are designed as so-called changers (CO)and can be used in systems with mineral oils, fluid greases or oiled compressed air. The pressure switches can be used at temperatures of up to 60°C and comply with protection class IP 65.
The comparable model of type 176-112-000 is also manufactured by SKF and, in contrast to the pressure switches DS-W20-4 and DS-W12-4, is designed as a closer (NO). The series can even be used at operating pressures of up to 80 bar and works with a nominal switching pressure of 20 bar. The permissible maximum temperature is 80°C.