Measuring instruments, geophysical instruments

Water level indicator

PASI best sellers all over the world, water level indicators measure the piezometric level of a liquid (usually water) intended for fast measurements in wells and tanks by a single operator, who can work comfortably on the surface. It is a portable instrument, easy to use and simple to maintain, ideal for monitoring the variations in level of groundwater within piezometers, often used as the first instrument of monitoring for dams, for areas surrounding dumps and also in areas with high levels of groundwater drainage. The measurement is made using flexible probe with a diameter of just 10 mm. Water level indicators are also essential for monitoring wells and checking for contamination between groundwater at different depths and crossed by a single well. Sometimes, in addition, it can also be interesting to measure the temperature of the water inside the well. Similarly, in alluvial ground, it will be important to periodically check the bottom depth from the surface in order to check for silting up of the well itself, at the base of which the finer sediments not retained by the casing windows may accumulate.

Oil Water Interface

Oil water interface meters are portable instruments suitable for measuring the thickness of the supernatant (hydrocarbons, foam, trichloroethylene etc...) that may be floating on the surface of the water in wells and/or tanks. The instrument indicates the presence of water by means of two stainless steel spikes and an electronic circuit that measures the electric current circulating through the water. The instrument identifies the product by means of a special prism system. A beam of IR light is emitted by the sensor, hits the prism with an angle of 45 degrees and is refracted internally according to Snell´s Law. If the prism is immersed in a liquid with an optical index similar to that of the prism itself, the light beam will not be refracted internally, but will emerge from the prism. The absence of the pulse indicates that the prism is immersed in a liquid. A microprocessor determines that if the prism is in conductive fluid, this should be water. Lowering the probe into the well, the IR sensor determines the presence of the product (usually a hydrocarbon) at the depth indicated on the special millimetre-marked cable, while a conductivity sensor detects the water level below. The transition between the two media is indicated by the change from an intermittent tone and flashing light (product) to a continuous tone (water). Through a double adjustment of the sensitivity (one for the IR sensor and one for the conductivity sensor) these meters can also be used in the presence of very viscous oils or very saline water. The probe is pressurised and the oil/water interface will be found whether the product floats or tends to sink.