Fully automated flexible-wall permeameter for determining the hydraulic conductivity (k) of fine-grained and granular soils using constant head, falling head, and constant rate of flow (CRF) methods with closed-loop pressure/flow control.
Dual high-precision pressure/volume controllers maintain cell pressure, back pressure, and inlet/outlet heads; automatic switching of valves enables head reversal and bidirectional flow tests without manual intervention.
Electronic volume change device measures inflow/outflow to 0.001 mL (model-dependent) and reconciles with differential pressure/meniscus head sensors for robust k evaluation over several orders of magnitude.
Temperature-aware testing with built-in Pt100/thermistor input and automatic viscosity correction to 20 °C; optional circulating bath for constant-temperature operation.
Corrosion-resistant plumbing with quick-connects, bubble traps, fine inline filters, and vacuum de-airing stand for reliable saturation of low-permeability clays.
Pressure/volume controllers: 0–1 MPa range (model-dependent), resolution ≤ 1 kPa; volume resolution ≤ 0.001 mL
Cell pressure (σ3): up to 1 MPa; stability ≤ ±0.5 kPa
Back pressure: up to 1 MPa; programmable ramps/holds; B-value check supported
Head/gradient control: constant head (Δh) or constant Δp across specimen; automatic falling-head with electronic level tracking; CRF with closed-loop flow
Flow/volume measurement: electronic volume change device and/or bidirectional flowmeters; leakage check and line compliance compensation
Permeability range: approx. 10⁻⁹ to 10⁻² m/s (specimen/kit dependent)
Displacement/strain: vertical LVDT (optional) for consolidation settlement during σ′3 stage
Transducers: pore pressure at top/bottom, cell pressure, differential pressure (optional)
Data acquisition: ≥ 24-bit A/D; typical logging 1–10 Hz; event-based averaging and stability criteria
Automation: valve sequencing, head reversal, stepwise gradient, termination on steady-state flow, stability of k, or time limit
