Siemens: Air and cost savings with SIPART PS2
24 October 2016
Advantages of switching principle with piezopneumatic technology for positioners.
The Issue
Compressed air is one of the easiest sources of power to distribute and use. Unfortunately, compressed air as a transfer medium and method of energy storage is very cost-intensive in comparison to other options.
Pneumatic actuators are widely used because they are low in cost, fast-acting, flexible and inherently suitable for potentially explosive atmospheres. They require a permanent supply of compressed air at an appropriate pressure, quality and quantity. Air from the surrounding atmosphere must be compressed for this purpose, then purified of oil and particles to maximize the service life of the supplied components. The cost of compressed air is important, as about 18% of the total energy consumed by industrial electric motors is used to generate compressed air. Furthermore, the energy used by compressors makes up the largest component (65%) of the cost of compressed air.
The Solution
The use of an electropneumatic positioner with switching principle reduces air consumption, which affects energy costs and emissions. This technology allows facilities to reduce compressor sizes and quantities.
The air loss associated with conventional positioners is very expensive. The SIPART PS2, by comparison, uses air only when required, with the result that the SIPART PS2 quickly pays for itself.
The Principle
Due to the switching principle, the SIPART PS2 does not require compressed air in a steady state. Because it uses piezo elements the positioner don ́t need any additional power supply, but can be powered up with 4-20 mA or a fieldbus.
The SIPART PS2 uses a pneumatic valve block with piezo pilot valves to eliminate the need for a traditional I/P and spool valve, both of which bleed air.
Piezo-bending elements, functioning as electromechanical transducers, are the base technology of the pilot valves in the SIPART PS2 positioner. With the so-called direct piezoelectric effect, a piezo element is deformed when a voltage is applied to it, thus generating mechanical motion. Thanks to this principle, piezo valves require virtually no energy to maintain an active state.
When opening and closing the pilot valves of the PS2, the electrical energy consumption is very low as a result of the piezo elements. The energy is theoretical and ideally the piezo element only required during the switching operation. Once a switching position is reached, the piezo position is maintained with virtually no energy expenditure.
Compared to other transducer principles, the switching principle together with piezo elements enables higher switching dynamics of the pilot valve and thus leads to a higher dynamic control characteristic of the control valve.
Compared to analog positioners, the air consumption drops significantly.
The Benefit
Siemens offers a positioner with very low air consumption. The SIPART PS2 digital valve positioner has an internal air consumption of just 0.036 Nm3/h in a steady state, so the required electrical power to generate compressed air, energy costs and emissions is very low.
This offers you higher savings compared to other installed positioners and reduces your total cost, including the costs incurred by air generation, maintenance and material.
With the provided Cost of Air tool from by Siemens you can easily compare the cost savings between different manufacturer and Siemens SIPART PS2 positioner.
From standard applications to the fastest particle accelerator
in the world – SIPART PS2 masters all control tasks.