Dry Gas Seals Performance testing
Sealing material oil (liquid) performance testing and evaluation:
Rubber material seal oil (liquid) performance, the general use of standard test oil, according to the test conditions of the temperature conditions and test time under the soaking, through the soaking before and after the test value comparison (such as material hardness, tensile strength change rate, Elongation rate of change, volume change rate, compression set, etc.), to evaluate its performance.
No1 standard oil is "low volume increase oil", the composition of this mineral oil mixture is solvent-extracted, chemically treated, dewaxed paraffin residue and neutral oil;
No3 standard oil is a "high volume increase oil", by the selected naphthenic crude products, after vacuum distillation of the two components of the composition of the oil.
Different purposes of the material value of the assessment is not the same.
Third, the hydraulic oil (liquid) on the performance of the seal:
The sealing theory holds that there is a complete lubricating film between a dynamic flexible seal and its mating surface. In the normal state, it is with this layer of lubricating film to achieve the purpose of sealing and extend the life of the seal.
In the hydraulic system, the hydraulic oil (liquid) on the seal sealing performance in addition to the media / sealing material compatibility, oil viscosity, viscosity changes with temperature, reciprocating (rotating) movement speed, pressure and shaft, cylinder Or the material, hardness, geometry, surface finish of the piston rod, and the structure of the seal, etc., affect the sealing effect. In general, the formation of a continuous lubricating film can achieve the desired sealing effect.
Japan NOK company first in the world with the latest image processing technology to explain the seal of the seal principle. It is considered that the sealing mechanism of the oil seal (rotary and dynamic seal) is composed of two parts: lubrication characteristic and sealing principle. Lubrication characteristics: the friction characteristics of the oil seal by the fluid viscosity and sliding speed control, oil seal and the relative sliding surface of the shaft in the oil film separated from the lubrication state of movement, so keep the friction resistance is small, wear small. Sealing principle: oil seal sliding contact surface of the oil flow from the atmospheric side to the oil side and from the oil side to the atmosphere side of the cycle. The lubrication of the sliding surface is good, and the wear of the sliding surface can be prevented, whereby there is no leakage.
When the system movement speed is too high, the impact of continuous formation of the lubricating film, resulting in increased friction heat, beyond the temperature range of the sealing material is caused by damage to the seal. Pressure is too large, in addition to the formation of oil film, but also on the rubber seal produced a "squeeze" role, generally can be used to add "retaining ring" to improve. Or choose a small friction coefficient, good self-lubricating PTFE combination seal structure will help improve the friction between the friction between the high and low speed reciprocating motion and high pressure system cylinder piston, piston rod seal.