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Zeta series: High pressure piston pumps

The Zeta pumps were developed for use with all types of fluids, with a focus on gases under very high pressure (70 MPa; 10150 psi).

In addition to the large volume (250 ml), the aim of the development was to enable scientists and engineers to perform long-term experiments with an extremely low leakage rate.

 

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The massive spindle with a diameter of 55 mm and a spindle pitch of 9 mm enables high precision and stability under continuous load.

For precise recording of the thermodynamic state within the cylinder, the pump is equipped with a pressure transducer with an accuracy of 0.05% (FS; optionally 0.01) and a 4-cable Pt100 of the highest accuracy class. The following graph shows an example of the accuracy and precision of the system (Data recording of Carbon dioxide over one hour without piston movement).

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The Zeta pump is controlled with the DACS software. This allows free programming of test sequences. See also under (Data acquisition and control systems). In addition to the typical operating modes of constant flow, constant pressure and freely programmable flow or pressure sequences, DACS offers special operating modes.

The COOLPROP libraries are implemented in DACS, which can calculate the thermodynamic properties of 122 fluids as well as their mixtures. Since pressure and temperature are measured in the cylinder, the density and molar quantity can thus be calculated continuously. This makes it possible to have operating modes that allow a flow based on the molar quantity or a constant density. Other operating modes can be customised.

All surfaces in contact with the medium are made of austenitic steel (1.4435) which is hydrogen resistant.

The tightness of the system is based on several factors. For example, the machining of the piston's raceway is at the limit of what is technically feasible and is perfectly matched with the CNC-milled piston rings made of high-molecular plastic.  Furthermore, the cylinder head does not require a gasket and is welded using a special process so that there can be no losses due to O-rings or fittings.