Heat Flux Meter

Heat Flux Meter application in Fire Tests

In many fire test methods, the radiation level is specified and, therefore, it is of great importance that the radiative heat flux is well-defined and measured with sufficient accuracy. Radiative heat transfer is also the dominant mode of heat transfer in most real fires.

A heat flux meter is an instrument which measures the radiant and convective heat that is transferred from the fire environment to a sensing element. In practice, heat flux is most commonly measured with total heat flux meters of the Schmidt-Boelter (thermopile) or Gardon (foil) type. A typical design consists of a thermopile sensor, mounted on a metal body that is cooled by water. The body acts as a constant temperature heat sink. The thermopile sensor typically has a nearly black surface which is assumed to absorb all incident radiation, or which emissivity is given.

The incident heat flux onto the absorber creates a local temperature difference. This difference is measured, resulting in an output signal (voltage). As a first approximation, this voltage is linear with the heat flux received by the sensor. The measurement of the temperature difference is based on thermocouples or thermopiles, which are passive and do not require any external power.

Test standards using heat flux meter

• ISO 5657 Reaction to fire tests — Ignitability of building products using a radiant heat source

• ISO 5658-2 Reaction to fire tests — Spread of flame — Part 2: Lateral spread on building and transport products in vertical configuration

• ISO 5659-2 Plastics — Smoke generation — Part 2: Determination of optical density by a single-chamber test

• ISO 5660-1 Reaction-to-fire tests — Heat release, smoke production and mass loss rate — Part 1: Heat release rate (cone calorimeter method) and smoke production rate (dynamic measurement)

• ISO 17554 Reaction to fire tests — Mass loss measurement

• ISO 9239-1 Reaction to fire tests for floorings — Part 1: Determination of the burning behaviour using a radiant heat source

• ISO 9705-1 Reaction to fire tests — Room corner test for wall and ceiling lining products — Part 1: Test method for a small room configuration

• ISO 14696 Reaction-to-fire tests — Determination of fire and thermal parameters of materials, products and assemblies using an intermediate-scale calorimeter (ICAL)

• FAR 25.853

  Part II Flammability of Seat Cushions

  Part III Test Method to Determine Flame Penetration Resistance of Cargo Compartment Liners

  Part IV Test Method to Determine the Heat Release Rate From Cabin Materials Exposed to Radiant Heat

  Part V Test Method to Determine the Smoke Emission Characteristics of Cabin Materials.

Gardon Type Heat Flux Meter

A Gardon type heat flux meter has a round foil of constantan soldered to a copper body. When exposed to a heat irradiance, the heat flow is transmitted radially along the foil, creating a temperature gradient between the foil's centre point and the edge. This temperature difference is proportional to the absorbed heat flow and self-generates a linear voltage output.

It is based on thermocouple materials for measuring heat flux in the range up to 100 W/cm2 (1000 kW/m2). When the heat flux meter is exposed to a source of radiant heat it generates a DC voltage proportional to the incoming heat, which is converted into a measured heat flux level by reading the voltage through the instrument. It can be withstanded with a very high heat fluxes with a water cooling unit.

Features

• High heat fluxes.

• Flange design (φ 45mm), easy to install.

• Scratch resistant absorber painting.

• Protection cap.

• Sapphire window (optional)

• Maintenance-free water cooling unit (optional).

Specification

Schmidt-Boelter Type Heat Flux Meter

A Schmidt-Boelter type heat flux meter has a relatively thick thermopile mounted on a heat sink, the water-cooled body of the gauge. The absorbed heat is conducted perpendicular to the absorber surface through the sensor into the heat sink. The absorber has a relatively uniform temperature distribution. The temperature difference between the sensor and the body is measured by the multiple thermocouples connected in series in the thermopile.

It uses a thermopile sensor for measuring heat fluxes in the range up to 20W/cm2 (200 kW/m2). When the heat flux meter is exposed to a source of radiant heat it generates a DC voltage proportional to the incoming heat, which is converted into a measured heat flux level by reading the voltage through the instrument. The heat flux meter is water cooled and is available in 6 different ranges of heat flow meters.

Features

• Reinforced water-cooled tubes.

• Scratch resistant absorber painting.

• Protection cap.

• Easy to install.

• Maintenance-free water cooling unit (optional).

Specification

Accessories

Cooling Device

During the usage of the heat flow meter, cooling water needs to be introduced to take away the heat from the sensor to ensure the accuracy of the measurement and to avoid high temperature damage to the sensor.

MO-CD-300 is particularly designed for heat flux meter cooling and ensures that the sensor can work at optimum temperature by circulating the cooling water.

Features

• Totally enclosed refrigeration system, stable working, and reliable performance.

• Digital display and control, high precision temperature control, and uniform temperature.

• PID intelligent temperature control unit with learning function, better suited to the needs of users.

• Super silent circulation pump, the whole machine works quietly and with low noise.

• High performance refrigeration system and pump circulation system, suitable for long time continuous work.

• Enclosed water tank and piping structure to avoid coolant pollution and oxidation.

• Standard stainless steel inlet and outlet water connections can be equipped with a variety of fittings or hoses, and external closed circuit circulation.

• Real-time display of operating status and alarm status.

Heat Flux Recorder

Portable device to display, and record the heat flux value, maximum up to 4 channels in a time.

Features

• Portable design, which can be held in the hand or stand on the bench.

• Work in single channel or multiple channels, max up to 4 channels.

• Sampling frequency up to 1 time/channel/second.

• Heat flux and temperature measurement.

• Multiple data saving ways: Internal data saving, flash disk saving, and computer communication.