4AE3 U9 C2 Test Hard 25

Pressure Gauges

• The entire measurement range of a pressure gauge is checked using a calibration test bench.
• A less accurate method of testing a pressure gauge is by comparing it with a master gauge.
• Pulsations in the line leading to a pressure gauge can be restricted using a pulsation dampener.
• Loss of accuracy in pressure gauges can be caused by incorrect installation, vibration, and corrosion.

Remote Water-Level Indicators

• The pressure gauge in a remote water-level indicator is used to measure the pressure of the water column.
• The condensing pot in a remote water-level indicator is used to collect and condense steam, allowing the pressure gauge to measure the water level.

Differential Pressure Sensors

• A differential pressure sensor (DP-cell) is used to measure the difference in pressure between two points.
• The high side transmitter connection in a differential pressure level measurement setup is used to connect the DP-cell to the high-pressure side of the tank.
• In an open tank, the DP-cell bellows is connected to the bottom of the tank to accurately measure the liquid level.

Flow Measurement

• Ultrasonic transducers attached to the outside of a pipe can measure flow rate without disrupting the flow.
• Coriolis flow meters are used to accurately measure the mass flow rate of a fluid, compensating for density changes.
• A Coriolis flow meter measures the mass flow rate of a fluid by detecting the twist of the flow tube caused by the fluid's flow.
• Coriolis meters are commonly used in the oil, gas, and chemical industries.
• Coriolis meters can accurately measure the flow rate of liquids, gases, and slurries.

Temperature Measurement

• Optical pyrometers measure the temperature of an object by detecting the radiation emitted by the object.
• The red optical filter in an optical pyrometer reduces the effect of ambient light.
• Infrared thermometers have an advantage over optical pyrometers in that they can measure temperature in a more direct and accurate way.
• Infrared thermometers can measure temperatures ranging from -20°C to 3000°C.
• A limitation of infrared temperature detectors is that they can be affected by the emissivity of the object being measured.

Humidity Measurement

• Capacitive hygrometers measure the change in capacitance on a metal oxide as the relative humidity changes.
• Resistive hygrometers are fairly economical, durable, and have reasonable accuracy.

Gas Measurement

• Non-dispersive infrared (NDIR) detection is used to measure the concentration of gases such as CO, CO2, and CH4.
• Continuous emission monitoring systems (CEMS) are used to monitor the emissions of pollutants such as NOx, SO2, and CO.
• Oxygen is not typically monitored in a continuous emission monitoring system (CEMS).