Thermal Mass Flow Meter

Thermal mass flow meters are devices that measure total mass flow of gases or liquids. They are available in different types and are commonly used to determine the total flow rate of fluids and gases in closed pipes or conduits. Capillary-tube mass flow meters are an example of thermal mass flow meters.

Heat transfer principle

Thermal mass flow meters measure gas flow by using the heat transfer principle. A thermal mass flow meter has two thermometers placed in a sensing section. One temperature sensor monitors actual process values, while the other is a heater that maintains a constant differential temperature. The resistance to heat changes with flow rate, and the amount of energy required to maintain a constant temperature changes with flow rate. The basic thermal mass flow meter consists of two temperature sensors with an electric heater in between. The heater may be built-in to the pipe, or it can be external.

Another principle used to measure mass flow is the Coriolis effect. This effect occurs when a moving mass exerts force on a stationary body. This force changes with the mass of the mass and results in deformation. The flow rate of a fluid is proportional to the coriolis force. These meters are used in fuel balancing and monitoring, and they require accuracy to within 1%.

The heat transfer principle of thermal mass flow meters is based on the thermal dispersion theory. It is based on the fact that the heat absorbed by a fluid is directly proportional to its mass. For example, when a gas flows over a hot source, it absorbs heat and cools it, and the difference between the two sensors is proportional to its mass flow. The measurement of this process is the basis for the calculation of the mass flow rate.

When calibrating the device, the power and mass flow rate relationship is established. This allows for accurate measurements of mass flow. However, this meter is not suitable for fast-responding systems. For example, if the gas flow is fast-moving, the meter will not be accurate.

Types

Thermal mass flow meters are instruments used to measure the flow rate of gas or oil. They work by using the transfer of heat from a heated surface to the flowing fluid. Different types of thermal mass flow meters work in different ways. Some use pulse output and others use standard analog outputs. They are also available with digital bus communications and rugged transmitter enclosures.

Thermal mass flow meters are used to measure and monitor the mass flow of gases and liquids without having to correct for changes in the gas’s properties. They are a popular measurement tool for mass-related processes such as the regulation of low gas flows. They are especially useful for chemical processes, where the relative mass of unreacted and reacted ingredients is vital to the reaction.

Thermal mass flow meters can be divided into two types, impeller and turbine mass flow meters. The first type, known as an impeller, is directly in the path of the flow. The impeller is powered by a synchronous motor, which provides angular momentum to the flow. The turbine is located downstream from the impeller, and the torque it receives is proportional to the flow’s angular momentum. The turbine’s deflection angle is proportional to the torque, and the result is a measure of mass flow.

Thermal mass flow meters work on the same principles of heat transfer. They have a heating element and temperature sensors. As the flow rate increases, thermal energy is transferred. This heat transfer is then used to measure the flow rate.

Applications

Thermal mass flow meters provide a practical alternative to traditional flow meters for measuring gas flows in a wide range of applications. They are particularly useful for gas flow monitoring in distribution networks, as well as leak detection. This type of flow meter works by using the temperature difference between the flow rate and the temperature of the fluid.

This type of flow meter is composed of two platinum-resistance temperature sensors. One sensor serves as the temperature sensor while the other acts as a heater. While the first monitors the actual process value, the other acts as a reference to maintain a constant differential temperature. The amount of power required to maintain equilibrium is proportional to the molecular rate of the process gas.

Thermal mass flow meters can be used to measure and regulate low-pressure gases and liquids. They can also be used in other mass-related processes. For example, in chemical reactions, the relative masses of the reactants and unreacted components determine the rate at which the reactions can occur. Because thermal mass flow meters do not require any correction for changes in the gas’s properties, they are useful in a wide range of processes that require accurate mass flow measurement.

The rangeability and accuracy of thermal mass flow meters is excellent, but they have several limitations. The first is that the device must be clean. Its sensor must be cleaned frequently because fluids that cause the sensor to coat will make the meter inaccurate. Another drawback is that it cannot be used to measure gases with differing compositions. In addition, gas with aerosols or droplets may affect the accuracy of the device.

Thermal mass flow meters use the principle of thermal dispersion, which states that the rate of heat transfer in a fluid is proportional to its mass. For example, when gas flows over a heat source, it absorbs the heat and cools the heat source. The heat transfer rate is proportional to the mass of the gas and its thermal properties. By measuring the heat transfer, thermal mass flow meters can determine the rate at which the fluid is moving.

Cost

The cost of a thermal mass flow meter depends on its accuracy, its range, and the accuracy of the measurements it gives. The first type of meter measures the volume of the flow by regulating the electric power. The second type measures the amount of power required to maintain the difference in temperature. Both of these models have their advantages. For instance, the second type allows for higher ranges.

There are a number of thermal mass flow meter models available, from low-cost models to more expensive models. Generally, an inline model requires an opening in the pipe while an insertion model requires a full severance. Generally, insertion models are more cost-effective for large-diameter pipes.

The Coriolis mass flow meter is superior to the Thermal mass flow meter, but it is more expensive. The thermal mass flow meter manufacturer has a number of advantages over its predecessor, including increased sensitivity and better computational algorithms. Another advantage is its lower installation cost. If you need to use a meter for custody-transfer purposes, you should consider investing in one.

A thermal mass flow meter can measure both liquid and gas flows. Its basic design comprises two temperature sensors and an electric heater between them. The heater can be embedded in the pipe or protrude into the fluid stream. Alternatively, a probe-type thermometer is available to measure large flows.

One of the most important considerations when choosing a thermal mass flow meter is the flow rate. A thermal mass flow meter should be able to handle the flow of gases and liquids of all sizes.

Installation

In order to properly install a thermal mass flow meter, you must follow the manufacturer’s instructions. The meter’s display should be perpendicular to the direction of flow, and its axis should be parallel to the pipeline axis. Moreover, the error range should not exceed +-2.5.

There are several options for installation of thermal mass flow meters. Some are inline style and are plumbed directly into the process line. They include a flow section, and the sensing elements are mounted in the flow section. They are available in sizes ranging from 1/4” pipe to 4” pipe and in different end configurations.

Thermal mass flow meters can be installed horizontally or vertically. The horizontal installation is more flexible, and requires fewer straight pipes than the vertical installation. For optimal flow, installation requires pipe lengths of approximately 10 mm upstream and 5 mm downstream. Horizontal installation is also suitable for pipe lines carrying wet natural gas or high-humidity air.

When installing a thermal mass flow meter, you should always read the manufacturer’s instructions for installation. The name plate should include information about the media to be measured, the operating temperature, input and output signals, and ATEX classification. In addition, you should also check the sealing material for the instrument. You should ensure that the material is compatible with the process gas, otherwise, it may not perform well.

The display of a thermal mass flow meter can be adjusted easily and quickly. First, you must make sure that the probe is facing the upstream. If you are unsure of its orientation, you can request a special meter with a different orientation. You can also order a meter that features a vertical orientation. However, you must specify the “ROTATE” option when ordering the unit.