Digital Geotextile Permeability Tester

Digital Geotextile Permeability Tester

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Digital Geotextile Permeability Tester
  • Digital Geotextile Permeability Tester
Digital Geotextile Permeability Tester
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Digital Geotextile Permeability Tester

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Digital Geotextile Permeability Tester – QualiGTX™ GPT D

The QualiGTX™ GPT D Digital Geotextile Permeability Tester measures vertical water flow through single-layer and multilayer geotextile specimens under no-load conditions. Qualitest North America designed this apparatus around ASTM D4491, the permittivity test method widely used by North American laboratories. Its 10-inch color touchscreen simplifies test configuration, timing, and result monitoring. It provides laboratories performing routine acceptance testing with standards-based measurements without requiring the investment in a fully automated testing system.

The instrument accommodates geotextile specimens up to 20 mm thick within a Ø50 mm high-strength 304 stainless steel clamping assembly. It applies a hydraulic head differential of up to 250 mm H₂O. The integrated heating and cooling system regulates water temperature from 5 °C to 60 °C, with a resolution of 0.1 °C. A dissolved oxygen measuring device verifies water conditions before testing, while automatic timing operates across a 999-second range.

The lateral two-unit water supply stabilization system quickly establishes the required water head and minimizes surface fluctuations, reducing the waiting time before measurements can begin. The unit features a compact 750 × 720 mm footprint, weighs 120 kg, and operates on standard single-phase 220 V power without requiring a dedicated utility connection. Its automatic water supply maintains a constant hydraulic head throughout data collection without manual refilling. This combination of controlled testing conditions and straightforward operation makes it a practical upgrade for laboratories transitioning from manual permeameters.

Digital Geotextile Permeability Tester – QualiGTX™ GPT D Applications

The QualiGTX™ GPT D is suitable for laboratories requiring consistent, reliable geotextile permeability measurements for routine testing and quality verification rather than advanced research applications.

  • Geotextile Manufacturing Quality Control: Performs routine production lot inspections to verify permittivity values against declared specifications before products are shipped.

  • Construction Materials Testing Laboratories: Supports acceptance testing of filter and separation geotextiles supplied for road, railway, and earthworks projects.

  • Contractor and Site Laboratories: Verifies that delivered geotextile materials comply with project specifications before installation in subgrades or drainage systems.

  • Distributor and Importer Verification: Provides independent testing to confirm supplier declarations and assess incoming material shipments.

  • Highway and Municipal Drainage Work: Evaluates water flow capacity in edge drain wraps, trench drainage fabrics, and separation layers.

  • Landfill and Containment Projects: Checks whether drainage and protection geotextiles installed above liner systems satisfy specified design flow requirements.

  • Erosion Control and Slope Drainage: Tests filter fabrics installed behind revetments, gabions, and retaining structures.

  • Technical Colleges and University Laboratories: Provides practical instruction in the geotextile permittivity method using equipment aligned with the published testing procedure.

  • Product Development Screening: Enables preliminary comparisons of fiber types, basis weights, and bonding variables before undertaking comprehensive material characterization.

Standards

The QualiGTX™ GPT D complies with the apparatus requirements of the recognized North American test method for determining the water permeability of geotextiles in their uncompressed condition.

- ASTM D4491 – Standard Test Methods for Water Permeability of Geotextiles by Permittivity

Digital Geotextile Permeability Tester – QualiGTX™ GPT D Key Features

The QualiGTX™ GPT D combines touchscreen operation with a conditioned water supply in a compact, single-cell configuration. Its integrated controls simplify testing procedures and allow operators to concentrate on obtaining accurate measurements.

  • 10-Inch Color Touchscreen Control: Combines test configuration, timing, and result monitoring on a single display, allowing technicians to view measurements directly without manually recording gauge readings.

  • Automatic Digital Timing: Controls the measurement interval using an internal clock across a 999-second range, eliminating timing errors associated with manual stopwatches.

  • Lateral Two-Unit Supply Stabilization: Quickly establishes the target hydraulic head and stabilizes the water surface, minimizing delays before measurements begin.

  • Automatic Water Supply: Maintains a consistent hydraulic head throughout the collection period without requiring manual water replenishment.

  • Controlled Temperature Water System: Heats or cools the water supply between 5 °C and 60 °C, supporting accurate correction of test results to the 20 °C reference temperature.

  • 0.1 °C Temperature Resolution: Provides precise temperature readings to support the viscosity corrections required by the test method.

  • Dissolved Oxygen Measuring Device: Checks water conditions before testing and helps identify entrained air that could reduce measured flow by obstructing specimen pores.

  • High-Strength 304 Stainless Steel Clamp: Secures and seals specimens consistently while providing resistance to corrosion and deformation during extended operation.

  • Integrated Source Water Tank: Supplies water to the test cell through an onboard reservoir, eliminating the need for a permanently connected water supply at the testing bench.

  • Direct Result Display: Presents the calculated measurement upon test completion, allowing operators to proceed to the next specimen without performing separate calculations.

  • Compact Single-Cell Frame: Requires only a 750 × 720 mm footprint and operates using standard single-phase 220 V power, making it suitable for laboratories without specialized utility connections.

Theory and Method

Water flowing perpendicular to a geotextile's plane follows Darcy's law under laminar flow conditions. Accordingly, the discharge rate increases in proportion to the hydraulic head difference across the fabric. The QualiGTX™ GPT D secures the specimen within a Ø50 mm aperture, maintains a measured hydraulic head, and records the volume of water passing through the material over a specified time interval. The resulting discharge measurement, evaluated against the known hydraulic head, forms the basis of the test. The instrument maintains stable head conditions, water temperature, and water quality to minimize variations during measurement.

The test method determines permittivity, calculated by dividing the flow rate by the specimen area and then by the hydraulic head. The resulting value, expressed in reciprocal seconds (s⁻¹), characterizes the geotextile independently of its thickness. This is important because nominal specimen thickness can change during packaging, transportation, and handling, making thickness-dependent permeability coefficients less suitable for direct comparisons between fabrics. When required for design calculations, the permeability coefficient can be obtained by multiplying permittivity by the nominal specimen thickness.

Water viscosity decreases as temperature increases. Consequently, measurements taken without temperature correction can reflect changes in water temperature as well as the actual characteristics of the geotextile. The test method standardizes results against a reference temperature of 20 °C, making reliable temperature measurement essential. The QualiGTX™ GPT D provides water heating and cooling between 5 °C and 60 °C, with temperature readings available at 0.1 °C resolution. Its dissolved oxygen measuring device provides an additional water quality check. Dissolved gases can escape from the water and form bubbles within the specimen, obstructing pores and reducing the measured flow rate. Verifying water conditions helps identify this potential source of measurement variation.

Digital Geotextile Permeability Tester - QualiGTX™ GPT D Technical Specifications

Parameter Specification
Maximum Head Differential 250 mmH₂O (2,450 Pa)
Specimen Clamp Inner Diameter Ø50 ± 0.5 mm
Maximum Specimen Thickness 20 mm
Specimen Clamp Material High-strength 304 stainless steel
Timing Range 0 to 999 s
Temperature Range 5 °C to 60 °C
Temperature Resolution 0.1 °C
Temperature Control Heating and cooling
Dissolved Oxygen Measurement Included
Control System 10-inch color touchscreen
Water Supply Automatic, with source water tank
Head Stabilization Lateral two-unit stabilizing system
Voltage 220 V, 50 Hz (110V is also available)
Dimensions (W × D × H) 750 × 720 × 1,750 mm
Weight 120 kg

Delivery time varies upon stock availability. Our standard dispatch and shipping times are generally within 1 week, however for some high demand items the delivery may be extended to 2-3 weeks. If you require these items urgently please contact us to check accurate stock availability and to organize faster shipping methods.

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Important Delivery Information

Delivery time varies upon stock availability. Our standard dispatch and shipping times are generally within 1 week, however for some high demand items the delivery may be extended to 2-3 weeks.

Need it urgently? Contact us here to check stock and organize faster shipping.

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