According to the company, the new frictionless plunger bearing gives the control valves even better response and repeatability. In addition, the turn-down ratio (span) of the valves has been increased from 100:1 to 200:1 in comparison with the previous models.
The introduction of a new plunger bearing principle now makes it possible to eliminate a guide bush, therefore providing a completely frictionless bearing for the plunger. The elimination of solid-to-solid friction on the guide bush offers many benefits. Valves with frictionless plunger bearings feature better response, meaning the position of the plunger already changes with minimal differences in the input signal.
With the frictionless bearing Bürkert was also able to improve the behaviour in use with low pressures (< 100 mbar). Stick-slip effects, which could be observed in the valves of the previous generations in some applications, have now been eliminated. No friction at the guiding elements of the solenoid control valves also means no temperature increases at the bearings during operation of the valve
In addition to the standard Types 2871, 2873 and 2875, Bürkert offers a second series of solenoid control valves with simplified technology as a more economical basic version. The Types 2861, 2863 and 2865 are aimed at customers who use large quantities of solenoid control valves in standard applications, with less stringent requirements for performance of the valves in favour of reducing costs.
