Radiant Heat Transfer Index (RHTI) Tests

Radiant heat transfer (heat transfer by radiation) is the process by which thermal energy is exchanged between two surfaces in accordance with electromagnetic laws. When objects are not in direct physical contact with each other or are separated in air, the transfer of heat from an object with a higher temperature to an object with a lower temperature is called heat radiation. All physical substances, whether solid, liquid or gaseous, can emit energy through the process of electromagnetic radiation due to the vibration and rotation of their molecules and atoms. The intensity of this energy flow depends on the temperature of the object and the nature of its surface. Radiation occurs at all temperatures, and the emission rate increases with temperature.

Radiative heat transfer is a process in which heat waves are propagated, which can be absorbed, reflected or transmitted by a cooler object. The sun heats the earth with electromagnetic waves. Hot objects emit heat waves.

The "ISO 11612 Protective clothing - Clothing that protects against heat and flame - Minimum performance requirements" standard developed by the International Organization for Standardization (ISO) describes the performance requirements for protective clothing made of flexible materials designed to protect the user's body, excluding the hands, from heat or flame.

The performance requirements specified in the ISO 11612 standard are applicable to protective clothing that may be worn for a wide variety of end uses where clothing with limited flame spread properties is required and where the wearer may be exposed to radiant or convection or contact heat or molten metal splashes.

Unfortunately, those who work in facilities where high temperatures are used, such as iron and steel factories or glass factories, are exposed to high levels of radiant heat. This situation causes injuries to employees. Traditional fabrics such as cotton or polyester catch fire quickly, and high radiant heat limits a person's ability to work.

Clothing that provides protection against radiant heat reflects radiant heat back and provides a safe and comfortable working environment. This type of clothing is worn over other protective equipment to provide additional protection. These are used as a complement to protective clothing, not instead of them.

The main application areas of clothing that protects against radiant heat are: iron and steel industry, automotive industry, cement industry, ceramics industry, glass industry, shipbuilding industry and welding enterprises.

The purpose of the ISO 11612 standard is to determine minimum performance requirements for clothing that protects against high heat and flame. In this standard, performance levels are determined as follows:

• Level 1 indicates exposure to low risk perception
• Level 2 indicates exposure to moderate risk perception
• Level 3 indicates exposure to high risk perception

Radiant heat transfer index (RHTI, radiant heat transfer index) is determined as “C” according to the ISO 11612 standard and there are four levels. C1 is the lowest and C4 is the highest level of protection.

Meanwhile, in the standard “ISO 6942 Protective clothing - Protection against heat and fire - Test method: Evaluation of materials and material combinations when exposed to a radiant heat source”, two complementary methods (method A and method A) are included to determine the behavior of heat protective clothing materials exposed to heat radiation. B) is explained. Method A allows visual assessment of any changes in the material after the action of heat radiation. With Method B, the protective effect of the materials is determined. Materials can be tested by both methods or just one of them. Tests performed according to these test methods serve to classify materials; However, in order to make a statement regarding the suitability of a material for protective clothing, additional additional criteria must be taken into account.

Among the numerous testing, measurement, analysis and evaluation studies it provides for businesses in various sectors, our organization also provides radiant heat transfer index (RHTI) testing services with its trained and expert staff and advanced technological equipment.