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Automatic Geotextile Permeability Tester

Automatic Geotextile Permeability Tester
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Geotextile Permeability Testers
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Automatic Geotextile Permeability Tester - QualiGTX™ GPT A

QualiGTX™ GPT A automatic geotextile permeameter runs vertical water permeability tests on geotextiles and related products with minimal operator input. Qualitest North America configured the system for laboratories that process specimens in volume, where the minutes spent leveling, timing, and calculating add up across a shift. The control computer positions the water level, executes the head sequence, collects the flow, and returns the vertical permeability coefficient. Reports upload or print from the same screen.

Geosynthetics producers, hydraulic engineering laboratories, and infrastructure QC departments use the QualiGTX™ GPT A to qualify filter and drainage fabrics before they reach a project. A 304 stainless steel clamp holds a 50 mm specimen up to 20 mm thick, and the operator sets any head differential up to 250 mm. Flow measurement runs against a 0.1 s clock, which matters on high-permittivity fabrics where the collection window is short. A dissolved oxygen analyzer verifies test water before the run starts.

The 70 mm head differential test proceeds automatically through the 0.8 to 0.2 range, removing judgment calls that make one technician's numbers differ from another's. A 36 L stainless steel tank with compressor cooling and PID control keeps water between 10 °C and 60 °C. Wetted parts, including the tank, clamp, and water line fittings, are 304 stainless steel. The unit occupies 1,150 by 670 mm of floor space and weighs 180 kg.

Automatic Geotextile Permeability Tester - QualiGTX™ GPT A Applications

The QualiGTX™ GPT A suits laboratories supporting hydraulic, rail, and marine infrastructure, where filter fabric performance is verified batch by batch rather than sampled occasionally.

  • Dam, Reservoir, and Canal Engineering: flow capacity testing of filter and drainage fabrics placed against earth structures carrying continuous seepage
  • Railway Subgrade and Trackbed Materials: qualification of geotextiles that separate ballast from subgrade and drain water away from the formation
  • Marine and Port Construction: verification of fabrics used in breakwater cores, quay wall backfill, and reclamation containment bunds
  • Flood Defense and Levee Works: measurement of cross-plane flow for filter layers behind revetments and toe drains
  • Geotextile Production Line Testing: batch release checks against published permittivity values before rolls are dispatched
  • Highway and Airfield Drainage: assessment of edge drain wrap and separation fabrics under pavement structures
  • Mining and Tailings Management: testing of drainage fabrics in heap leach pads and tailings dam underdrain systems
  • Accredited and Third-Party Laboratories: high-throughput verification testing where operator-to-operator consistency carries as much weight as accuracy
  • Product Development and Failure Investigation: comparison of pore structure and manufacturing variables against measured cross-plane flow
Automatic Geotextile Permeability Tester

Automatic Geotextile Permeability Tester - QualiGTX™ GPT A Key Features

The QualiGTX™ GPT A automates the three steps that consume operator time in a vertical permeability test: leveling, timing, and calculation.

  • Automated 70 mm Head Differential Test: carries the run through the 0.8 to 0.2 range unattended, freeing the technician to prepare the next specimen
  • Self-Locating Zero Water Level: establishes the datum without shimming or eye-level judgment, so setup is identical on every specimen
  • Programmable Head Height: enter any water level within the 250 mm differential range to suit the protocol or the fabric under test
  • 0.1 s Timing Resolution: resolves short collection windows on free-draining fabrics where a manual stopwatch introduces meaningful error
  • Controlled Water Supply Metering: feeds replacement water at a measured rate so the driving head holds through the full collection period
  • Dissolved Oxygen Analyzer: reads oxygen content in mg/L, percent saturation, and partial pressure, putting water condition on record before testing
  • 10 °C to 60 °C Thermostatic Tank: heats or cools the supply and holds it to ±0.5 °C so results stay comparable between summer and winter runs
  • Automatic Volume and Time Capture: logs collected water against elapsed time with no manual reading, cutting transcription mistakes
  • Automatic Coefficient Calculation and Reporting: converts flow data into the vertical permeability coefficient and builds the report for upload or printing
  • Selectable Test Configurations: choose between vertical permeability protocols in software, letting one instrument serve several reporting requirements
  • Computer Control with a Short Learning Curve: walks the operator through setup and retains parameters between runs, easing technician handover
  • Temperature Deviation Correction to 0.1 °C: trims the measured value so viscosity corrections rest on a verified reading rather than a nominal one
  • User-Tunable PID with Auto-Tuning: adapt the thermal loop to your ambient laboratory conditions instead of accepting factory defaults
  • 304 Stainless Steel Tank and Specimen Clamp: hold up to continuous water contact and repeated clamping without corrosion
  • 304 Stainless Steel Water Line Fittings: keep the flow path clear of corrosion products that would foul the specimen or bias readings
  • Electrostatic Powder-Coated Working Vessel: protects the stainless steel vessel surface in humid laboratory conditions

Theory and Method

Cross-plane flow through a geotextile follows Darcy's law while flow remains laminar, meaning the discharge rate stays proportional to the hydraulic gradient across the fabric. The QualiGTX™ GPT A imposes a known head difference on the clamped specimen and measures the water volume passing through a fixed 50 mm aperture over a recorded interval. Dividing discharge by area, head, and time yields permittivity, expressed per second. Multiplying permittivity by the nominal specimen thickness converts it to a permeability coefficient in velocity units.

Repeatability is the practical problem in this measurement, not raw accuracy. Head height, timing start and stop, and the point where an operator judges the level steady all shift between technicians, and each shift moves the result. The QualiGTX™ GPT A locates the zero water level itself, drives to the programmed head, and starts and stops collection on its own clock. Removing those three judgment points is what tightens the spread between operators testing the same material.

A steady head is what keeps Darcy's law applicable during the run. Water leaving through the specimen lowers the supply level, and a falling level means a falling gradient and a flow rate that drifts downward as the test proceeds. The QualiGTX™ GPT A meters replacement water at a controlled rate to hold the level where the operator set it. Dissolved gas works against the same goal, since microbubbles inside the pore structure block flow paths, so the oxygen analyzer checks water condition before measurement.

Automatic Geotextile Permeability Tester - QualiGTX™ GPT A Technical Specifications

ParameterSpecification
Maximum Head Differential250 mm
Specimen Clamp Inner DiameterØ50 ± 0.5 mm (304 stainless steel)
Maximum Specimen Thickness20 mm
Timing Range0 to 9,999 s
Timing Accuracy0.1 s
Temperature Measurement Range0 °C to 110 °C
Temperature Control Range10 °C to 60 °C
Temperature Control Accuracy±0.5 °C
Thermometer Accuracy0.1 °C
Temperature Correction Accuracy±0.1 °C
Dissolved Oxygen Range0 to 20 mg/L; 0 to 200 %; 0 to 400 hPa
Dissolved Oxygen Accuracy±1.5 % FS
Dissolved Oxygen Repeatability±0.5 % FS
Dissolved Oxygen Resolution0.01 mg/L; 0.1 %; 1 hPa
Water Supply Tank Capacity36 L
Temperature Control ModesCooling and heating
Cooling MethodCompressor unit
Temperature ControlPID with auto-tuning
Compressor Power550 W
Internal Circulation Pump Power100 W
Circulation Pump Flow Rate15 L/min
Total Power1 kW
Dimensions (W × D × H)1,150 × 670 × 1,580 mm
Weight180 kg

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Geotextile Permeability Testers