Laser level transmitters use the speed of light to measure the level of liquid. A laser transmitter at the vessel top fires a short pulse of laser light down to the liquid surface which then gets reflected back to the detector in the same assembly. A timing circuit measures the elapsed time and calculates the distance. In case of high temperature or pressure conditions such as Reactors, a special sight glass window is used to contain the process conditions and separate the transmitter from process. Sight glass should be able to pass the laser beam without diffusion and attenuation.
- lasers have virtually no beam spread (0.2° beam divergence) and no false echoes, and can be directed through spaces as small as 2 in.2
- Laser give precise readings, even in vapor and foam.
- They are ideal for use in vessels with numerous obstructions and can measure distances up to 1500 ft.
- Bulk solids
- Opaque liquids such as dirty sumps, milk, and liquid styrene.
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