Analysis of the advantages and disadvantages of the Metso locator ND7000 and the Siemens PS2
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Could some expert help analyze the Metso locator ND7000 and the Siemens PS2? Are their working principles the same? Does the Siemens model with remote feedback come with it, while the ND7000 doesn’t? Does Siemens rely on the principle of electrical balance? Does the ND7000 operate on the principle of torque balance? Could a teacher analyze it from a performance perspective?
This post was last edited by tiger2010 on 2020-4-24 at 10:51. The working principle is similar; the only difference lies in the type of valve inside the actuator (the Metso ND7000 uses a slide valve, while the Siemens PS2 uses a piezoelectric valve)； As for whether feedback is included or not, it depends on your order; the standard version does not include it. I have never used Metso’s ND7000, so it’s difficult to compare the performance of the two.
Hello, are piezoelectric valves better than slide valves? What are their advantages and disadvantages?
This post was last edited by tiger2010 on 2020-4-24 at 18:10. As already mentioned, I have never used Metso’s valve types; it seems that Flowserve offers a combination of piezoelectric valves and slide valves, but I haven’t conducted a detailed comparison yet – it’s necessary to look at actual performance data for comparison.
Metso’s 700 series of positioners includes the electro-pneumatic valve positioner NE700, as well as the pneumatic-pneumatic positioner NP700. These are traditional type positioners that have been around for decades; they are highly classic and offer excellent reliability. The Siemens PS2 electro-pneumatic valve positioner is an intelligent positioner that supports HART communication. I have tested multiple large-scale projects that use this locator, and the PS2 exhibits excellent reliability and stability. Its piezoelectric valve has good reliability. Typically, the adjustment accuracy of intelligent positioners is better than that of conventional mechanical positioners. I recommend using PS2. The selection of a locator is very important. Smart locators are popular these days, but the reliability of smart locators produced by some manufacturers is poor. Never rely on the surface-level data; no matter how well they are promoted, if they don’t hold up under actual testing, they are worthless. FISHER’s 6000 series, SAMSON’s 3730-3, Siemens’ PS2, and Yamaki’s AVP300 are all excellent options; among them, Siemens and SAMSON models allow for the setting of forward and reverse operation, while the other two models require that these settings be specified at the time of ordering. The Metso ND9000 series, and the Foss MD520, lack reliability – multiple units of these models have encountered problems, and the root cause lies in their design; it’s complicated to explain. It’s not clear whether any improvements have been made over these 5 years, so it’s advisable to avoid using them.
Do not use Siemens ones; they leak severely after one year of use (which causes valve surging). We’re excluding our current project (with an investment of 100 billion) right away. Just take a look at Zhejiang Petrochemical, and you’ll understand.
Leakage in Siemens? Is the air supply clean and dry? The piezoelectric valve will get damaged if water gets in it
Agreed; we used a batch of PS2 units (around 300 in total), and the plastic seals on the air intake grills and amplifiers leaked air severely, causing significant fluctuations in the valves.