Interfacial leakage of elastomer seals at low temperatures

Abstract

Interfacial leakage of air in hydrogenated nitrile butadiene rubber (HNBR) O-ring seals exposed to sub-ambient temperatures is studied. Flange-type fixtures with sealing surfaces produced by 3 different surface finish processes are used. When the seals are cooled down to temperatures below the elastomer glass transition point T g of (−23 • C), an abrupt increase of air leakage (> 10 −2 cm 3 /min) is observed. The effects of surface finish conditions, compression ratio, grease lubrication and additions of carbon black in the HNBR on the cold leakage are discussed. Persson's contact mechanics and effective medium leakage theory coupled with finite element analysis (FEA) of the HNBR seals are utilized to capture the changes in the contact area and pressure with cooling and predict the seal failure temperatures. The main cause for the cold seal failures is believed to be the detachment of the elastomer seals from their mating sealing parts due to the elastomer thermal contraction and the negligible recovery of the HNBR in cold environment. In addition, the adhesive rubber-substrate interface influences the detachment and seal failure.

Evaluation Analysis on Leakage Performance for Beam Seal With Two Sealing Areas

“…Lorenz and Perrson compared the theoretically calculated leakage with the experimentally measured leakage to verify the accuracy of sealing theory [9]. Akulichev et al used Perrson's leakage model and finite element analysis to predict the seal failure temperature of Oring seal [10]. However, Bottiglione pointed out that the selection of parameter l/L (the ratio of sealing interface transversal length to longitudinal length) in Perrson's model would cause prediction uncertainty of the leak rate, and a better estimation of the cross-sectional height of the leakage channel should consider the real separation between the two sealing surfaces [11].…”

The effect of hot air exposure on the mechanical properties and carbon dioxide permeability of hydrogenated nitrile butadiene rubber (HNBR) with varying carbon black content

“…One relevant elastomer property for seal performance is the way in which gases diffuse through these elastomers because, in addition to leakage around a seal [28], diffusion through the materials determines how well they can seal a gas environment. The combination of gas diffusion properties and mechanical properties affects the resistance of elastomers to rapid gas decompression (RGD) damage [29,30].…”

Influence of Randomness in Rubber Materials Parameters on the Reliability of Rubber O-Ring Seal

“…Yang et al [15] studied the wear and damage behavior of O-rings under harsh conditions. Akulichev et al [16] studied the effects of different surface treatment processes on sealing performance. In addition, the aging of the rubber significantly affects the physical properties of the seal [17,18].…”