Pressure sensor in permeameter

[AsbAli]

Hi,
Can anybody recommand a way to estimate of head loss of a pressure sensor. For my filter test I want to install pressure sensors as many as it gets.
How many sensors are effective and how should the sensores be arranged? (I mean for example in one side of cylinder or around the cylinder or another way)

thanks in advance

 

[Dima7]

Is that for lab or field test?

 

[fattdad]

I'm imagining a cylinder with some soil in it. I'm imagining a network of sensors that measure the head pressure at various points in the cylinder. I'm imagining a hydraulic head on the upgradient side of the cylinder. I'm imagining a hydraulic head on the downgradient side of the cylinder. I'm thinking you may be trying to calculate the hydraulic conductivity.

Is any of my imagination correct?

What is your ultimate objective?

What is your test setup other than the need for pressure sensors?

f-d

¡papá gordo ain’t no madre flaca!

 

[AsbAli]

Hi,
This filter test is a laboratory test. I made a cylinder like a permeability test cylinder.There is a two types of material in this cylinder, one of them is clay and the other is gravel and sand.

Assume the cylinder had dimensions of 30 cm diameter and 1000 cm height and had 16 holes for the pressure sensors at various points.

I am trying to calculte(measure) the depth of penetration of base soil(clay) in filter material (Gravel and Sand) and measure the mass loss of base soil materials.

I wanted to find out how the effect of pressure sensores ís and I am trying to estimmate the head loss and make the most effective holearrangement for the pressure sensors.

my final objective is to say if a defined base-filter combination is safe or not? I know that safe or unsafe is a question of tolerable depth of penetraion or tolerable loss of base material.

thank you

Asb

 

[mdhshanwil]

Your test sounds very similar to a granular filter analog of the Gradient Ratio Test (ASTM D 5101), a standardized test method to determine the compatibility of geotextile filters with base soils. The GR test is run in a rigid permeameter using manometers placed at various elevations in the sample to determine head loss within the base soil, and head loss across the filter. There are some modified (better, I think) versions of the test--see literature from Fannin (mid-90s to present) and Fischer (mid- to late 90s). The test allows direct measurement of base soil mass loss.

A highly modified version, called the Flexible Wall Gradient Ratio (FWGR) test was developed by Harney and Holtz in the late 90s (see paper in 2001 North American Geosynth Conf, Portland OR). The FWGR uses a flexible membrane instead of a rigid cell, and uses differential pressure transducers to measure head loss. Note that the differential pressure transducers must be sensitive enough to capture very small head losses (specimen length is ~small). You can determine the proper sensor range and sensitivity by a quick (rough) calc of the head losses you expect for your type(s) of material and your designed length between measurements. The FWGR uses 4 measurement points in the middle portion of the sample - 2 pairs on opposite sides, for redundancy. A fifth measurement is made just upstream of the filter. A sixth measurement is sometimes made just downstream of the upstream edge of the base soil, to check for blinding at this interface (it's been common for these tests to blind at this location, esp if the influent water has not been thoroughly filtered (1-5 micron) and freed of organisms (algae, bacteria, esp if the test will be run long-term).

Sounds like you could use some concepts from these tests, and modify them for your setup.