Level

By generating high frequency sound waves and evaluate the echo which is received back by the sensor.

Blocking Distance is when ultrasonic and radar sensors take a small amount of time to be transmitted

Anything that will effect the signal like foam, dust, condensation

• Foam
• Dust 
• Condensation 
• Anything that will effect the signal

• No
•  It varies based on the medium that it is traveling through.

• Radar transmitters work by emitting a radio signal. 
• When the beam detects a change of impedance it will reflect a signal back to the receiver. The amount of signal returned is dependent upon the change of impedance. 

Radar signals travel along a wire rope or rod that extends from the transmitter head and are used when there are obsicles in the tank that may effect the signal  

Use guided radar

Use 2 probes at top and bottom of ofthe tank, and as the level in the tank increases the capacitance of the probe increases and the level is measured.

Fit a transmitter to the top of a tank and this transmitter reading is subtracted from the bottom transmitter reading as the bottom transmitter will read the pressure of the liquid plus the head pressure. The head pressure is subtracted from the bottom reading

So maintenance can be made to a transmitter without emptying the tanks, this done by transferring the pressure from the tank to the capillary tube that connects to the transmitter

Suppressed zero is where transmitters are not at tank level and a capillary tubes is added to measure the pressure so that reading can be added to the reading 

Elevated zero is where a transmitter is located above the bottom of the tank, and the amount that the transmitter is above the tank needs to be subtracted from the transmitter reading.

An air bubbler system uses a tube with an opening below the surface of the liquid level where a fixed flow of air is passed through a tube with an opening below the surface of the liquid level. The Pressure in the tube is proportional to the depth and density of the liquid over the outlet of the tube.

• Radiation
• nuke it!!

Gamma radiation is electromagnetic radiation of high frequency which means it has a very short wavelength

Cobalt and caesium

The half-life is a measure of radioactive decay and is the time it takes the isotope to decay to half its original size. 

• A Scintillator is a tube that produces a pulse of light when it detects gamma rays. 
• It works by using a photo multiplier to amplify a signal to produce a series of pulses which measures the amount of gamma rays received. 

The Geiger-Muller-tube consists of a glass tube filled with an inert gas like Argon. There is a cathode and anode with a high voltage and when the gamma rays strike the tube it will discharge and produce a series of counts where the frequency is dependent on the amount of radiation received.

The tuning fork sensor consists of a piezo transmitter, a receiver and circuitry to produce an output when the level is reached.

The float has a magnetic coupling to a switch inside the transmitter unit. As the float rises the transmitter will produce an alarm output.