
\documentclass[english,landscape]{ptbposter}
%\documentclass[ngerman,sanserif]{ptbposter}

\phone{+49-30-3481-7467}
\fax{+49-30-3481-7503}
\email{Ute.Becker@ptb.de}
\workingGroup{7.54 Vacuum Metrology}
\department{7.5 Heat and Vacuum}
\location{10587 Berlin}
\street{Abbestraße 2--12}
\QRcode{http://www.ptb.de/cms/fachabteilungen/abt7/fb-75/ag-754.html}

\Author{Peter}{Silie}[Physikalisch-Technische Bundesanstalt]
\Author*{Max}{Mustermann}
\Author{Gerhold}{Dosenkohl}[Muster Universität Forschungsstadt]
\Author*{Ellen}{Bogen}[XYZ GmbH]

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\title{Das Liebesleben der Maikäfer}

\begin{document}

\begin{multicols}{2}
\section{Introduction}

Regarding to the Kyoto Protocol, the European Union and its members have
committed themselves to reduce the emissions of refrigerant greenhouse gases,
like R-134a, during the period 2008--2012. To control the emission of
refrigerant equipment, it is necessary to check the accuracy of leak detectors
and room controllers. In the European standard EN 14624 it is pointed out, only
to use calibrated leaks (called sniffer test leaks) based on a primary
standard.

\begin{itemize}
 \item The range of the PTB primary standard is from $4\cdot10^{-11}$ mol/s to
 $4\cdot10^{-9}$ mol/s which is the most needed range in industry of around 1 g
 loss per year of the cooling agent R134a.

%%%\includegraphics[width=0.5\linewidth]{TL2}
%%%\includegraphics[width=0.495\linewidth]{skizze}

The leakrate $q_{pv}$ is calculated by $q_{pv}= \frac{\Delta V}{\Delta t} \cdot
p_{atm}$ and the molar flow follows from $q_{\nu} = \frac{q_{pV}}{R\cdot
T_{wv}}$.
\end{itemize}
\section{Measurements}
There are two types of leaks, capillary and permeation leaks. Both kinds of
leaks contain the gas R-134a which flow to atmospheric pressure. With the
following measurements the influence of the fill pressure, the atmospheric
pressure on the leak rate and stability is examined.
\begin{itemize}
 \item The capillary leak is equipped with a pressure reducer and generates a
 gas flow of $q_{\nu}=8\cdot10^{-3}$\,Pa\,l/s. The measurements did not show a
 significant dependence on the fill pressure and the atmospheric pressure,
 however the repeatability is $\pm\,3.4\,\%$.

%%%\includegraphics[width=0.8\columnwidth]{qvonpatmcap}

\item The permeation leak is equipped with a Teflon membrane and generates a
gas flow of $q_{\nu}=1\cdot10^{-3}$\,Pa\,l/s. In the following graph the mean
leak rate is shown vs. different fill pressures. The measurements show a
significant dependence on the fill pressure $p_{fill}$ and the atmospheric
pressure $p_{atm}$. The slope of the linear least square fit determines the
atmospheric coefficients $(\Delta q_{\nu}/q_{\nu}(1010\,hPa))/\Delta p_{atm}$ of
the flow rates. The uncertainty bars show the standard deviation of repeat
measurements.The permeation leak is equipped with a Teflon membrane and
generates a gas flow of $q_{\nu}=1\cdot10^{-3}$ Pa l/s. In the following graph
the mean leak rate is shown vs. different fill pressures. The measurements show
a significant dependence on the fill pressure $p_{fill}$ and the atmospheric
pressure $p_{atm}$. The slope of the linear least square fit determines the
atmospheric coefficients $(\Delta q_{\nu}/q_{\nu}(1010\,hPa))/\Delta p_{atm}$
of the flow rates. The uncertainty bars show the standard deviation of repeat
measurements.


%%%\includegraphics[width=0.8\columnwidth]{qvonpatmper}

In the next step, the data were normalized for a gas flow $q_{\nu}$ at an
atmospheric pressure of 1010\,hPa. Thus the fill pressure coefficients $(\Delta
q_{\nu}/q_{\nu}(1bar))/\Delta p_{fill}$ could be calculated.

%%%\includegraphics[width=0.8\columnwidth]{qvonpfill}

\end{itemize}
\section{Results}
\begin{center}
 \begin{tabular}{@{}lll@{}}
    \toprule
      & capillary leak & permeation leak \\
    \midrule
 $(\Delta q_{\nu}/q_{\nu}(1010\,hPa))/\Delta p_{atm}$ & - & $ \leq -0.0063/hPa $ \\
 $(\Delta q_{\nu}/q_{\nu}(1bar))/\Delta p_{fill}$ & - & $\leq 0.46/bar$\\
  repeatability & $\pm 3.4 \%$ & $\pm\,0.7\,\% \cdots \pm\,1.6\,\%$ \\
    \bottomrule
    \end{tabular}
\end{center}
So far, no temperature dependence could be measured due to consistencies
probably caused by experimental shortcoming.
\end{multicols}

\end{document}
