In 1983 the total sensor market was nearly $ 5 billion. The largest segments were flow meters, temperature, level, and pressure sensors. Flow meters are used extensively in the chemical industry, the largest segment of the process control market. Sales of all types of flow meters exceeded $ 1 billion in 1983. Level sensors are also used in chemical plants, but they are also used in the gas and oil transportation segment. Sales of liquid level sensors was $ 500 million in 1983. That same year, sales of temperature sensors was more than three quarters of a billion dollars.