Our pressure switch test units PRO VC or the “dynamical pressure controller ” PRO VC are in use where very low pressures has to be reguated with high precision or the pressure has to be in-/ decresed stepless.
Electro pneumatical controllers (see EPK) that generate these very low pressures with a static system, have the disadvantage that pressure and temperature fluctuation in the environment can impair the measuring results very quickly or even make a measurement impossible, because the setpoint specification is readjusted to the actual value and is then not stable enough at higher requirements.
The pressure controllers PRO VC don´t have such a disadvantage because they generate the reference pressure by an “open” system. This openness of the reference pressure generation provides a highly stable comparative pressure even when large membranes of the pressure switches change their own volume up to the nominal pressure very significantly.
The pressures controlled in this way can still work with a resolution of 0.001 mbar (100mPa) at the smallest ranges of 0…2 mbar. For economic reasons, the maximum control range is around 40 bar, because the PRO VC has a steady low air consumption, which is not relevant for supply from the house network, but interferes with higher pressure.
The PRO VC can be used for the dynamic pressure generation, which is particularly necessary for pressure switch calibration, or can generate a quasi-static reference pressure. The nozzle, which is very precisely controlled by a stepper motor, provides the freely selectable rising or falling output pressure. If a static pressure is required, the device precisely regulates the setpoint.
During pressure switch calibration, the switching points are precisely checked and adjusted to maintain a high quality standard. So far, in many cases, this check has been carried out manually, with all the resulting error possibilities such as nonlinear pressure increase and pressure drop.
Pressure rise and pressure drop times can be determined to ensure the greatest possible reproducibility of the tests.
Specimen outputs are measured and displayed by the PRO VC in mV, V or mA data, with pressure switches the switching event is frozen or stored.
For dynamic specimens a range can be defined for the upper and lower switching points; it is also possible to repeat a pressure curve several times.
Different software versions allow a customized configuration of a test station.
At the beginning of a test process, the specimen is connected to the PRO VC pneumatically and electrically. A type definition is loaded on the screen that represents the type properties of the specimen. This means that the test procedure is defined and the calibration can be started.
The pressure changes now depending on the stepper motor-driven throttle. The pressure curve is displayed numerically or graphically and the program records the measured values for defined events and displays them. These recorded values can be saved or printed out after completion of the testing process.
Due to our own software development in-house, we can take customer requirements for connection to database systems or networks into account.
An important argument for the use of computer-controlled test systems is an easy operability. After configuring the unit and describing the type definitions, reproducible results can also be carried out by unskilled and / or changing personnel.
Summary:
- The pressure specification of the dynamic pressure regulators PRO VC is carried out by a stepper motor-controlled nozzle.
- Due to the constant minimum flow of the open pressure system, pressure fluctuations in the calibration environment practically do not affect the calibration system.
- Measuring range 0…1 mbar to -1…40 bar
- If several measuring ranges are required, these are realized by a dynamic pressure line with corresponding “taps” for the pressure outputs.
- To each pressure output a reference pressure sensor is assigned, which converts the pneumatic pressure into an electrical signal and makes it available for the computer add-on card or for the PC for further processing.
- Standard measurement accuracy of the reference sensors < ± 0.1 % of full scale, via selection < ± 0,01% of full scale
- With isolating valves at the respective pressure outputs, these can be inactivated or activated in each case and further a possible leakage of the connected specimen can be measured.
- For faster pressure rise and, above all, pressure drop times, there is a “pressure jump valve” in the throttle supply line.
- The desired output pressure is generated by the computer by positioning the stepper motor. The system pressure is displayed digitally on the computer screen and can also be removed analogously.
- A variety of measuring ranges and interfaces are available (options).
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