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Geotextile Longitudinal water flow tester

Geotextile horizontal permeability tester, Longitudinal water flow tester

Model: UT4071A; ISO 12958, ASTM D4716

The Geotextile Horizontal Permeability Tester (also called In-Plane Water Flow Tester or Horizontal Permeability Apparatus for Geosynthetics) is a specialized laboratory instrument engineered by UnitedTest to measure the in-plane water flow capacity, horizontal permeability coefficient (kₕ), and transmissivity (θ) of geotextiles and geotextile-related products under constant head flow and controlled normal pressure.


This equipment is indispensable for geosynthetic quality control labs, highway & railway engineering, landfill drainage design, water conservancy projects, and geotechnical research institutions.

ISO 12958-1 Index test for determination of in-plane water flow capacity

General Introduction

Geotextile Horizontal Permeability Tester — GB/T 17633 & ISO 12958 Compliant | UnitedTest


The Geotextile Horizontal Permeability Tester (also called In-Plane Water Flow Tester or Horizontal Permeability Apparatus for Geosynthetics) is a specialized laboratory instrument engineered by UnitedTest to measure the in-plane water flow capacity, horizontal permeability coefficient (kₕ), and transmissivity (θ) of geotextiles and geotextile-related products under constant head flow and controlled normal pressure.


This equipment is indispensable for geosynthetic quality control labs, highway & railway engineering, landfill drainage design, water conservancy projects, and geotechnical research institutions.


Geotextile horizontal permeability tester, Longitudinal water flow tester

This model is the cost-effective basic model launched by UnitedTest for conventional testing scenarios. It retains all standard test functions required by GB/T 17633 and ISO 12958, and adopts manual operation mode, which is suitable for users with conventional test volume and limited budget.


Main features

  • Key Features
  • Standards Compliance
  • Test Principle
  • Applications
  • Test Procedure
  • Keywords

Structural Design: Acrylic + aluminum profile frame — corrosion-resistant and visually clear for observation

Loading System: Pneumatic normal pressure loading, safe and reliable

Head Control: Manual adjustment via lifting screw; water head height read from scale with ±1 mm accuracy

Water System: Built-in water tank (≈120 L) for environmental adaptability

Manual adjustment of test water head and normal compressive pressure, with intuitive mechanical scale display

Manual timing and water volume collection through professional measuring tools

Test data is recorded and calculated manually by operators to obtain in-plane flow rate and transmissivity

No intelligent software system, simple equipment structure, low failure rate and convenient maintenance


Ideal For: 

Ideal for small and medium-sized geotextile manufacturers, university teaching laboratories, engineering vocational colleges, and institutions with low-frequency routine quality inspection. It is the best cost-performance choice for basic standard compliance testing.

Projects where budget is a primary consideration

Laboratories performing standard index tests per GB/T 17633 / ISO 12958-1

ISO 12958-1 Index test for determination of in-plane water flow capacity

ISO 12958-2 Performance test under simulated boundary conditions

GB/T 17633 Geotextiles and geotextile-related products — Determination of water flow capacity in their plane

SL/T 235 Specification for geosynthetic testing (China Water Conservancy)

JTG E50 T1143 Highway engineering geosynthetic test protocol

ASTM D4716 Standard test method for in-plane flow of geotextiles under constant head


Under a specified hydraulic gradient and in contact with defined boundary materials, the tester applies a controlled normal compressive stress (simulating overburden load) to the saturated geotextile specimen. Constant-head water flows in-plane through the specimen. By measuring the volumetric flow rate over a timed interval, the instrument calculates:


  • In-plane water flow rate q [L/(m·s)]



  • Horizontal permeability coefficient kh [cm/s]



  • Transmissivity θ [cm³/s]


Per ISO 12958-1:2020, the apparatus must feature a minimum width of 200 mm, a minimum net hydraulic length of 300 mm, accommodate specimens up to 50 mm thick, maintain normal pressure tolerance within ±5%, and limit leakage to ≤5% of measured flow.


UnitedTest Geotextile Horizontal Permeability Testers are widely deployed for:

Highway & Railway Engineering: Drainage performance validation of geosynthetics in subgrade and retaining structures

Landfill & Environmental Engineering: Leachate drainage layer design

Water Conservancy: Dam filtration and drainage blankets

Coastal & River Protection: Revetment and erosion control systems

Manufacturing QC: Geotextile production line quality verification

Independent Testing Institutes: Third-party certification per GB/T 17633, ISO 12958, ASTM D4716

Specimen Preparation: Cut geotextile specimens of appropriate dimensions; saturate in water containing 0.1% non-ionic surfactant for ≥12 hours to remove air bubbles

Assembly: Place closed-cell foam rubber → specimen → upper foam rubber → pressure plate

Initial Seating Pressure: Apply 2 kPa normal pressure; flush with de-aired water to expel residual air

Stabilization: Adjust normal pressure to 20 kPa and hold for 360 s

Gradient Setting: Set hydraulic gradient to 0.1 (or as specified); allow flow for 120 s

Measurement: Collect outflow in a graduated cylinder over a timed interval

Calculation: Compute in-plane flow rate, permeability coefficient, and transmissivity

Multi-pressure Testing: Repeat at 20 kPa, 100 kPa, 200 kPa (per ISO 12958-1) or project-specified stresses

Geotextile Horizontal Permeability Tester, In-Plane Water Flow Tester, GB/T 17633-2019, ISO 12958, Geosynthetic Horizontal Permeability Apparatus, UnitedTest, Automatic Horizontal Permeability Tester, Geotextile Transmissivity Test, Constant Head In-Plane Flow, ASTM D4716 Equipment

Main Technical Specification

Equipment StructureIncludes a sample installation device, water supply device, constant water level device, loading device, and water level measurement device.
Sample SizeWidth not less than 100mm, length should be more than twice the width.
Normal Force Adjustment Range0-500kPa
Water Level Adjustment Range0-300mm
Dimensions700*500*1700mm
Power220V, 50HZ, 1 phase
Weight70Kg



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