ISO 188-2011 pdf free download

ISO 188-2011 pdf free download.Rubber, vulcanized or thermoplastic — Accelerated ageing and heat resistance tests
Caoutchouc vulcanisé ou thermoplastique — Essais de résistance au vielilissement accéléré et a ía chaleur.
4.1.1 General
The oven shall be of such a size that the total volume of the test pieces does not exceed 10 % of the free space in the oven. Provision shall be made for suspending test pieces so that they are at least 10 mm from each other and, in cabinet ovens and ovens with forced air circulation, at least 50 mm from the sides of the oven.
The temperature of the oven shall be controlled so that the temperature of the test pieces is kept within the specified tolerance for the specified ageing temperature (see Clause 8) for the whole ageing period. A temperature sensor shall be placed inside the heating chamber close to the samples to record the actual ageing temperature.
No copper or copper alloys shall be used in the construction of the heating chamber.
Provision shall be made for a slow flow of air through the oven of not less than three and not more than ten air changes per hour.
Care shall be taken to ensure that the incoming air is heated to within ±1 °C of the temperature of the oven before coming in contact with the test pieces.
The ventilation (or air change rate) can be determined by measuring the volume of the oven chamber and the flow of air through the chamber.
NOTE To ensure good precision when doing ageing and heat resistance tests, it is very important to keep the temperature uniform and stable during the test and to verify that the oven used is within the temperature limits with regard to time and space Increasing the air speed in the oven improves temperature homogeneity. However, air circulation in the oven and ventilation influence the ageing results With a low air speed, accumulation of degradation products and evaporated ingredients. as well as oxygen depletion, can take place. A high air speed increases the rate of deterioration. due to increased oxidation and volatilization of plasticizers and antioxidants.
4.1.2 Cell-type oven
The oven shall consist of one or more vertical cylindrical cells having a minimum height of 300 mm. The cells shall be surrounded by a thermostatically controlled good heat transfer medium (aluminium block, liquid bath or saturated vapour). Air passing through one cell shall not enter other cells.
Provision shall be made for a slow flow of air through the cell. The air speed shall depend on the air change rate only.
4.1.3 Cabinet oven
This shall comprise a single chamber without separating walls. Provision shall be made for a slow flow of air through the oven. The air speed shall depend on the air change rate only, and no fans are allowed inside the heating chamber.ISO 188-2011 pdf free download.