Flow Meters for Maintaining Temperature

Best Thermal Liquid Flow Meter and Perfect Solution for Comprehensive Heat Control


Flow meters for maintaining temperature are solutions often sought after by the die casting industry. This sector faces several thermally-related challenges.


Proteus Industry’s thermal flow meters are the perfect solution for comprehensive heat control. They operate by optimizing the flow rate of the cooling fluid and temperature at the outlet and inlet. The flow meter maintains temperature uniformity all through the die by controlling the heat transferred between the surface of the die and the cooling fluid.


What are thermal mass flow meters?


Thermal flow meters are used in gas flow and liquid measurement applications. A majority of them are used in gas uses. Thermal flow meters work by placing a heat source in the flow stream and measuring the heat dissipating using one or more temperature sensors.


What principle do they operate on?


When a liquid makes contact with a hot object, the liquid takes the heat away from it, consequently increasing the temperature of the liquid. This is how thermal mass flow meters measure flow.


What types of thermal flow meters are there?


There are three main types of thermal flow meters. All measure fluid flow rate by detecting the heat lost from the heated surface.


Thermal Dispersion/Immersible Type- The heat is removed towards the boundary layer of the flowing fluid across the heated area.


Capillary Tube Type- Heat transfer occurs via a tiny heated capillary tube that runs parallel to main flow path. Several mass flow controllers or MFCs are based on this type of design.


Temperature Differential Type- It involves two RTDs, one is unheated and the other is heated; both are attached on the outer portion of the tube. The difference in temperature read by the two RTDs is the primary flow signal. During high flow conditions, the differential is on the lower side because flow reduces heat. When the flow rate is low the differential is high because less heat is removed.


How is the heat that is dissipated measured?


There are two electronic methods for measuring heat loss.


  • Constant Temperature Differential- There are two temperature sensors- one is heated and the other sensor measures the temperature. The flow rate is calculated based on the electrical power necessary to maintain the temperature difference between the sensors.
  • Constant Current Method- this is a less popular technique. It entails two sensors; one heated and the other measures the temperature in the flow stream. The power of the heated sensor is held at a constant. Flow rate is calculated as the difference between the temperatures of the heated sensor and flow stream.


Both the Constant Temperature Differential and Current Method techniques operate on the principle that a high velocity flow rate results in a larger cooling effect.


What are the benefits of using thermal mass flow meters?


Thermal mass flow meters operate independently of pressure, viscosity and density. The accuracy rate of this type of meter is 1 to 2 percent. They have no unobstructed flow path or any moving parts.


What are the costs associated with thermal mass flow meters?


Flow meters for gas measurements can range between a few hundred dollars up to thousand dollars. Mass meters for liquid applications cost up to a two thousand dollars.

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