GB/T 18153-2024 Safety of machinery — Safety data to establish temperature limit values for touchable hot surfaces
1 Scope
This document specifies the burn value for human skin in contact with the hot surface of the machine or workpiece, and describes the method for determination of hot surface temperature limit values used to prevent skin burns.
This document does not specifies hot surface temperature limit values for specific machines or workpieces, and does not gives data on pain prevention.
This document is applicable to contacts where the surface temperature remains substantially unchanged (see 4.1) during contact and the contact period is not less than 0.5s.
This document is not applicable to large areas of skin and hot surfaces that are in contact with approximately 10% or more of the body's skin.
This document also not applicable to contacts that exceed 10% of the skin on the head, or that cause burns to significant parts of the face.
Note: In some cases, the results of contact with hot surfaces may be more serious, such as:
— burns that cause respiratory obstruction;
— extensive burns of 10% or more of the body's skin may damage the circulatory system due to fluid loss;
— excessive heat to the head or body, even in the absence of burns, may cause an unacceptable heat stress response.
2 Normative references
The following documents contain requirements which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 15706-2012 Safety of machinery - General principles for design - Risk assessment and risk reduction
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 15706-2012 and the following apply.
3.1
touchable hot surface
machine or workpiece surface whose temperature is not lower than 43°C, which skin may come into contact with
3.2
surface temperature
Ts
temperature of machine or workpiece surface
3.3
contact period
duration of skin-to-surface contact
3.4
thermal inertia
properties of an object in the process of heating or cooling due to its heat transfer properties
Note: Thermal inertia is usually expressed as the product of the material's density (ρ), thermal conductivity (K), and specific heat capacity (c).
3.5
burn threshold
temperature threshold between skin contact with a hot surface without burn and superficial partial thickness burn during the specified contact period
Note: The severity of burns is divided into:
— superficial partial thickness burn, that is, the epidermis is completely destroyed except for the shallowest burns, but the hair follicles, sebaceous glands and sweat glands are not damaged;
— deep partial thickness burn, that is, most of the dermis and all sebaceous glands are destroyed, only the deep parts of the hair follicles or sweat glands survive;
— full thickness burn, that is, the whole layer of skin had been destroyed, and the epithelioid components have all died.
4 Burn threshold
4.1 General
The surface temperature of skin and hot surface contact resulting in burning is related to the surface material and the length of period of skin contact with the surface. The relationship between the burn value and the contact period is shown in Figure 1. The thermal inertia of several groups of materials in Figure 1 is similar, so are the burn thresholds.
Contents
Foreword
Introduction
1 Scope
2 Normative references
3 Terms and definitions
4 Burn threshold
4.1 General
4.2 Burn value data
5 Method for determination of surface temperature limit values
5.1 Identification of touchable hot surfaces
5.2 Analysis tasks
5.3 Selection of appropriate burn threshold
5.4 Determination of surface temperature limit values for different contact periods
Annex A (Informative) Procedure for determination of surface temperature limit values
Annex B (Informative) Contact period
Annex C (Informative) Thermal inertia of materials
Bibliography
