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,**.  1  ,0  ,**.  +,  +* A New Simple Gas Permeameter for Permeability Measurement of Small Samples
of Volcanic Eruptive Materials and Experimental Run Products
Shingo TAKEUCHI῍ and Satoru NAKASHIMA῍῍
In order to measure permeabilities of small volcanic eruptive materials and experimental run products, wedeveloped a new simple permeameter to measure gas permeabilities of millimeter-size samples. This permeametercan measure permeability in the wide range from +*+1 to +*+* m,, with the precision within one order ofmagnitude. Nitrogen gas is used as a working gas. The permeability is calculated by using Darcy’s law applied
to results of steady state gas ﬂow measurement at ﬁxed pressure di#erences up to +./+*. Pa (ca. *.+/ atm). The
pressure di#erence is measured with the precision of +* Pa by a water column manometer. Gas ﬂow rate isconverted to water ﬂow rate in an acrylic container and the water ﬂow dripping from the container through thetube into a ﬂask is monitored by an electric balance.
We conﬁrmed the accuracy in permeability measurement by measuring gas ﬂow in a stainless capillary tube(+/ mm in length and +** mm in inner diameter). We carried out ﬂow measurement with the pressure di#erenceof +.,+*, to +..+*. Pa at the ﬂow rate of -./+*+* to -.3+*2 m-/s. Measured gas ﬂow rate was comparedwith calculated ﬂow rate, assuming that the gas ﬂow in the capillary tube is Poiseuille ﬂow. Although thedi#erence between them becomes large for smaller ﬂow rate than +*3 m-, the discrepancy is within *.,/ log unit
for the ﬂow rate larger than +*+* m-/s. Permeabilities of centimeter-size, four air-fall pumice and scoria
measured by this permeameter are consistent with the permeability-vesicularity relationship obtained frompyroclastic materials by Klug and Cashman (+330).
We measured permeabilities of nine samples of porous ceramics with varying dimensions from +.- to 2.- mm
in length and from / to 12 mm, in cross sectional area, which were cut from a homogeneous ceramic rod.
Permeabilities of millimeter-size samples are consistent with those of ca. + centimeter-size samples, indicatingthat this permeameter can determine permeability for the millimeter-size samples.
The permeameter can be easily assembled with commercially available components at a very low cost, and will
be a useful tool to measure permeabilities of small volcanic eruptive materials and experimental run products.
Key words : gas permeameter, permeability measurement, degassing, vesiculation+ῌ ῐ ῎ ῑ ῏+:E0&FGH>IJK LMD+:EN@O'  !"#$%& (PQ#RS/@TUV89IW@ XYZ Eichelberger#'()*+,$-./012 34560

et al., +320 ; Klug and Cashman, +330 ; Melnik and Sparks,789:;<&=>?@A 3452 BCD+333A 1 )*;7V[\:V<6]+/,ῌ2//+ ^_`abcGde ,ῌ+,ῌ+^_fgGhGhifhjklmnoplhqr
Department of Earth and Planetary Sciences, Tokyo
Institute of Technology, Ookayama ,ῌ+,ῌ+, Tokyo+/,ῌ2//+, Japan.
]+/,ῌ2//+ ^_`abcGde ,ῌ+,ῌ+^_fgGhGhifhjklsthuv

Interactive Research Center of Science, Tokyo
Institute of Technology, Ookayama ,ῌ+,ῌ+, Tokyo+/,ῌ2//+, Japan.
Corresponding author : Shingo Takeuchi
e-mail : takeuchi@geo.titech.ac.jp

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Table +.

Results of permeability measurements for pyroclastic fall samples.

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6

Table,. Results of permeability measurements forsmall porous ceramic.

Fig. -. Measured permeabilities of several pyroclastic falls plotted against their vesicularities.
Error bars for vesicularities are ¶, vol.ῌ due
to uncertainty of solid density (¶+** kg/m-) ofrock samples. Error bars for permeabilities are
standard deviation (,s) of replicate measurements. Bold solid curve indicates the relationship obtained by Klug and Cashman (+330)
from 1- samples of pyroclastic materials. Two
ﬁne solid curves indicate the upper and lower
limit of the scattered permeability data for these1- samples.

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