DescriptionThe BTU-STC-2AP dual‑gang variable head automatic permeameter is a
laboratory apparatus that integrates consolidation and permeability
testing. It can simultaneously apply consolidation pressure and
seepage pressure, measuring the permeability coefficient of soil
specimens using the variable head method. The instrument includes a
built‑in multi‑channel 16‑bit AD acquisition unit and dedicated
data acquisition and processing software, enabling automated
measurement of water level changes and consolidation deformation.
It is suitable for permeability studies of fine‑grained soils and
some coarse‑grained soils. Test Standards- ASTM D5084(Standard test methods for measurement of hydraulic conductivity of
soils using variable head)
- ASTM D2435(Standard test methods for one‑dimensional consolidation properties
of soils)
- ISO 17892‑11(Geotechnical laboratory testing – Determination of permeability)
- GB/T 50123‑2019(Standard for geotechnical testing method – Variable head
permeability and consolidation tests)
Specification| Item | Parameter | | Structure | Dual‑gang (2 independent channels) | | Specimen diameter | ≥ 61.8 mm | | Specimen cross‑sectional area | ≥ 30 cm² | | Specimen height | 40 mm / 20 mm | | Consolidation pressure range | 0 – 800 kPa | | Permeability pressure range | 0 – 200 kPa | | Specimen compression | ≥ 10 mm | | Variable head cross‑sectional area | ≥ 0.785 cm² | | Water level measurement range | 0 – 40 cm (differential pressure sensor) | | Water level measurement accuracy | ≥ 0.1 cm (likely means ≤0.1 cm; typical accuracy is higher) | | Vertical displacement sensor (optional) | 0‑12.7 mm, accuracy ±0.01 mm | | Power supply | 24 V DC, power ≤ 24 W | | Data acquisition system | Built‑in multi‑channel 16‑bit AD acquisition unit, USB
communication, capable of acquiring 2 channels of digital dial
gauges and 2 channels of volume change sensors | | Software | BTU Data Acquisition & Processing Software V2.1 |
Detail- Consolidation pressure application system: Composed of a pressure regulator, LCD digital pressure gauge,
cylinder pressure piston, cylinder, linear bearing, ball valve set,
and reaction frame – enables precise control of consolidation
pressure.
- Permeability cell: Includes cutting ring, upper/lower porous stones, pressure cap,
guide ring, sealing ring, clamping ring, fixing screws, cell base,
and quick‑connect fittings – complete structure with good sealing.
- Permeability pressure application system: Uses a pressure regulator, air‑water conversion permeameter tube,
LCD digital pressure gauge, and ball valve set to provide stable
and controllable seepage pressure.
- Instrument base: Made of bent sheet metal, integrates the permeability cell,
loading frame, and cylinder; the front panel is equipped with 6
ball valve assemblies, power switch button, etc.
- Water level measurement: A volume change sensor (or differential pressure sensor) measures
water level changes with a range of 0–40 cm and accuracy of 0.1 cm.
- Display and control: The panel includes precision LCD digital displays, air‑water
conversion measuring tube, pressure regulator, and water supply
tank.
- Data acquisition: Built‑in 16‑bit AD acquisition unit connects to a computer via
USB, simultaneously acquiring 2 channels of displacement and 2
channels of volume change signals.
- Low power design: 24 V DC power supply, ≤24 W – suitable for long‑duration tests.
- Optional accessory: Vertical displacement sensor (0‑12.7 mm, accuracy ±0.01 mm) for
measuring consolidation deformation.
Application- Variable head permeability coefficient determination for
fine‑grained soils (clays, silts) and some sandy soils
- Combined consolidation‑permeability tests to study the effect of
pressure on permeability
- Evaluation of seepage characteristics for earth dam cores,
roadbeds, and impervious materials
- Automated teaching and research in university and institutional
geotechnical laboratories
- Obtaining permeability parameters of soil layers in geotechnical
site investigations
Advantages- Dual‑gang design: Tests two specimens simultaneously, improving efficiency and
saving time.
- Integrated consolidation + permeability: Allows application of consolidation pressure to simulate in‑situ
stress conditions before permeability testing – more representative
of actual field conditions.
- Highly automated: Built‑in acquisition unit + software automatically records water
level changes and consolidation deformation, reducing human error.
- Wide water level measurement range: 0–40 cm with 0.1 cm accuracy – meets variable head test
requirements.
- Precise pressure control: Uses LCD digital pressure gauges, pressure regulators, and
cylinders – consolidation pressure up to 800 kPa, permeability
pressure up to 200 kPa.
- Low power & safe: 24 V DC supply, low power consumption – suitable for long‑term
laboratory operation.
- Flexible options: Optional high‑precision displacement sensors for simultaneous
consolidation compression measurement.
What To Choose| Requirement | Recommendation | | Need simultaneous consolidation and permeability testing | Integrated design – allows variable head test immediately after
consolidation | | Variable head permeability testing of fine‑grained soils | Accepts φ≥61.8mm specimens, meets standard geotechnical test
requirements | | Improve test efficiency | Dual‑gang structure – tests 2 samples in one run, reduces
repetitive work | | Automated data acquisition | Built‑in 16‑bit AD + software – automatically records water level
and displacement, generates curves | | Simulate in‑situ stress conditions | Consolidation pressure 0-800 kPa – can simulate stresses at various
depths | | Low power, safe operation | 24 V DC, ≤24 W – suitable for unattended long‑duration tests |
Process Flow- Specimen preparation: Prepare a soil specimen of φ61.8mm × 40mm (or 20mm) according to
standard procedures.
- Specimen installation: Place the specimen into the permeability cell (cutting ring +
upper/lower porous stones), install sealing components, and
tighten.
- System connection: Connect the consolidation pressure system, permeability pressure
system, water level sensor, and optional displacement sensor.
- Apply consolidation pressure: Set the desired consolidation pressure (0–800 kPa) using the
pressure regulator; allow the specimen to consolidate under the
specified pressure, recording compression.
- Apply permeability pressure: After consolidation stabilizes, set the permeability pressure
(0–200 kPa) and start the variable head permeability test.
- Data acquisition: The software automatically records water level drop (or volume
change sensor readings) vs. time, and optionally records
displacement changes.
- Calculate permeability coefficient: The software automatically computes the permeability coefficient
using the variable head formula.
- Generate report: Produce a test report including water level‑time curves,
permeability coefficient results, and consolidation deformation
data.
|
