What are thermal mass flow meters used for?

Thermal mass flow sensors are most often used for the regulation of low gas flows. They operate either by introducing a known amount of heat into the flowing stream and measuring an associated temperature change or by maintaining a probe at a constant temperature and measuring the energy required to do so.

What is a thermal method of flow measurement?

Flow Measurement Thermal mass flowmeters are used primarily to measure the flow rate of gases. The mass flow rate is inferred in one of two ways: (a) by measuring the temperature rise in the flowing material or (b) by measuring the heater power required to achieve a constant set temperature in the flowing material.

What are the different types of thermal flow meters?

CHAPTER 2FLOW METER TYPES & PRINCIPLES

• ELECTROMAGNETIC FLOW METER.
• KARMAN VORTEX FLOW METER.
• PADDLE WHEEL FLOW METER.
• FLOATING ELEMENT FLOW METER.
• THERMAL FLOW METER.
• DIFFERENTIAL PRESSURE FLOW METER.
• ULTRASONIC FLOW METER.
• CORIOLIS FLOW METER.

What is a thermal dispersion flow meter?

Thermal mass flow meters are also known as thermal dispersion or calometric flow meters. They operate on the principal that a flow stream produces a rate of heat transfer, where heat is removed and cooling takes place, that is proportional to the mass flow of the media. This difference is translated into a flow value.

How do you calibrate a thermal mass flow meter?

Thermal Flow Meter Factory Calibration The calibration process involves placing the sensor in one of several different test sections, flowing a known amount of gas through the pipe and then measuring the signal to obtain the desired overheat. This is done at minimum 12 times over the operating range.

How does a thermal mass flowmeter determine the flow inside the pipe by using heat?

Thermal mass flow meters employ the thermal dispersion principle whereby the rate of heat absorbed by a fluid flowing in a pipe or duct is directly proportional to its mass flow. In a typical thermal flow meter gas flowing over a source of heat absorbs the heat and cools the source.

What is high thermal mass?

‘Thermal mass’ describes a material’s capacity to absorb, store and release heat. For example water and concrete have a high capacity to store heat and are referred to as ‘high thermal mass’ materials.

How does a thermal dispersion flow switch work?

Based on the principle of heat transfer, the thermal dispersion flow switch consists of two temperature sensors. When the flow rate drops there is less cooling, which causes an increase in the temperature difference. When liquid is flowing, there is a temperature difference between the two sensors.

What are the advantages of ultrasonic flow meter?

High stability: Transit-time meters are unaffected by the temperature, density or concentration of the liquids they measure, making them a more stable measuring device. Ability to measure liquids and gasses: Ultrasonic flowmeters can be used to measure a wide variety of liquids.

How accurate are ultrasonic flow meters?

Magmeters are highly accurate, with inaccuracies of ±0.5 percent of rate or less. In comparison, transit-time ultrasonic meters have inaccuracies of ±1 to 2 percent of rate. Cost comparisons depend greatly on the specific project rather than meter cost. Both meters can provide cost-effective flow measurement.

How does a mass flow meter work?

How does a mass flow meter work? Mass flow meters operate either by introducing a known amount of heat into the flowing stream and measuring an associated temperature change or by maintaining a probe at a constant temperature and measuring the energy required to do so.