ZEBIS - air sampler for isotopes aboard the Zeppelin NT
Functional principle
The concept of the air sampler ZEBIS (Zeppelin based isotope sampler) is to sample ambient air probes in special canisters (SilcoCanTM, Restek GmbH). The air samples are later on analyzed in the laboratory for stable isotope ratios.
The following procedure is applied:
Each canister module consists of 4 canisters which are pressurized by an articulated piston pump (NPK 09 DC, KNF Neuberger) at defined times. By exceeding a pressure of 4 bar absolute the canister is closed automatically by a magnetic valve (Fa. Clippard). If the pressure threshold is not reached the valve is closed by the control electronics after a defined time period. This avoids problems with pressure cutoff or with leaks.
In addition to this automatic mode the valves in front of the canisters can be operated manually. The closing of the valves can be carried out by applying the pressure control or manually. The pump is operated permanently which assures a constant flush through the tubing. A NO magnetic valve (normally open) at the end of the tubing system is activated at the same time with the NC magnetic valve (normally closed) of the respective canister.
To analyze this procedure later on, pressure, status of the magnetic valves and some more housekeeping signals (e.g. temperature) are stored by a data logger. The whole control electronics is embedded in a 19'' component part carrier (3 height units). On top of that sub-rack, the data logger is affixed. The readout of the data logger occurs through an external USB access.
