15. Enhancing operability of the fuel system units in the hot climate conditions

Annotation: The article dwells on the problem of enhancement of durability for the mechanical rubber articles, which is directly related to the enhance of rubber resistance to various types of heat aging. Heat resistance during compression is most important for rubbers used for seals of various types: rings, collars, armored collars, gaskets for aviation and rocket technology hardware. Stress relaxation and the accumulation of relative residual deformation of rubbers, caused by the kinetic rearrangement of chemical bonds, are extremely sensitive to the influence of high temperatures. The main cause of the defects is the loss of elastic properties of the seals because of the accelerated heat aging of the nitrile group under conditions of long-term exposure to elevated temperatures in conditions of hot climate. The results of accelerated climatic testing of specimens of mechanical rubber articles, as well as the results of climatic endurance testing of the units for the period simulating 20-year service life are specified, and the main types of defects which result in the loss of performance properties of the mechanical rubber articles are as follows: great (up to 100%) residual deformation of intersections, cracking, loss of elasticity. The warranty life of fuel system units, made of ИРП-1078 nitrile rubber, does not exceed 12 years. Replacing the existing rubbers with rubbers created on the basis of more heat-bearing rubbers is the most promising way to improve the performance properties of the mechanical rubber articles under the high temperatures. The new D2301 rubber is based on fluorosiloxane rubber. It provides high thermal stability and, especially, the ability to maintain high performance properties for a long time under the simultaneous impact of hostile environment and high temperatures. The results of climatic endurance testing of fuel system units, equipped with rubber articles made of D2301 rubber, fully justify the increase of the specified service life of the specified units from 12 to 16 years. It is recommended to introduce D2301 rubber into the effective normative documentation and continue studies in order to extend the nomenclature of mechanical rubber articles made of D2301 rubber to provide the reliable sealing of units during the service life of 16 years or longer.