FAQ#019 – Which is the difference between HAE (high-air entry) and LAE (low-air entry) filters?

HAE (High air entry) filters are normally used to monitor pore pressure in the clay core dams and saturated low permeability soils. “High air entry” means high-resistance to air entry when the filter is saturated. The surface tension of the water in the very fine porus of the filter prevents entry of air. The HAE filters must be saturated before installation by means of the saturation device.

LAE (Lowair entry) filters are often used in medium and soft soils. They do not need to be saturated by special device because the porosity of the filter permits water entry with simple immersion.

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