Calculation of the Operational Characteristics of the Impulse Gas-Barrier Face Seal

Abstract

Abstract The problem of reducing leaks along the pump or compressor shaft of pumped liquids and gases into the environment is very urgent. Serious difficulties have to be faced when sealing the shafts of machines that pump aggressive, toxic, explosive and fire-hazardous environments. According to modern occupational safety requirements, such pumps and compressors should use double seals with a barrier medium whose pressure exceeds the sealed one by 0.05-0.2 MPa. Currently, liquid-lubricated double mechanical seals are widely used in chemical production equipment, however, over the last decade of the 20th century, leading companies have developed a number of designs of double gas mechanical seals for pumps and chemical production devices, which significantly exceed liquid-lubricated seals in their performance characteristics. The vast majority of these seals use a gas-dynamic principle of operation, i.e. spiral, logarithmic, T-shaped or other micro grooves are made on the sealing faces of their rings, which, when rotated, create an additional gas dynamic force that ensures the functioning of these seals with a micron gap between the sealing pair. In this paper, the design, principle of operation and engineering methodology for calculating the main characteristics of a impulse gas barrier face seal, in which one pair of sealing rings performs the functions of a double mechanical seal, is considered. The design is simple, compact and, thanks to the more advanced principle of creating a gap between the sealing pair, is able to maintain operability in a wide range of sealing and barrier pressures. The existing experience of operating seals of this type on chemical production pumps has confirmed their high efficiency, reliability and safety.