Español
Pусский
In selection of mechanical seals, low temperature media such as liquid ammonia, liquid oxygen, liquid chlorine, liquid hydrogen, etc. have their own specific standards.
This is determined by characteristics of these media. Characteristics of low temperature media are: 1.Materias become brittle at low temperature, and need to be selected carefully.
2.Sealing ring is easy to age and lose its elasticity, which affects the sealing performance of mechanical seal.
3.Since medium temperature is low, water molecules in atmosphere will freeze on sealing surface, which will accelerate wear of friction pair of mechanical seal.
4.Friction and heat of sealing surface will cause sealed medium to vaporize, make friction pair of mechanical seal form dry friction, and burn the sealing surface.
5.Material expansion and contraction should be taken into account, and selected materials should have similar expansion coefficients.
These characteristics determine requirements and selection criteria for mechanical seals as follows: 1. When temperature of medium is higher than -45°C, a single mechanical seal can be used, but it is necessary to pay attention to freezing of moisture in atmosphere, which will cause the mechanical seal to fail.
2. When medium temperature is higher than -100℃, it can be sealed with bellows mechanical seal.Dry nitrogen is blown to sealing face to isolate the sealing face from atmosphere and prevent water molecules from freezing.
3.When medium temperature is lower than -100℃, static bellows structure is used to prevent the bellows from fatigue and damage.
4.Appropriate friction pair materials should be adopted, such as QSn6.5-0.1 bronze filled PTFE.
5. Mechanical seals with low end face specific pressure and low POV value should be adopted to strengthen quenching and flushing.
This is determined by characteristics of these media. Characteristics of low temperature media are: 1.Materias become brittle at low temperature, and need to be selected carefully.
2.Sealing ring is easy to age and lose its elasticity, which affects the sealing performance of mechanical seal.
3.Since medium temperature is low, water molecules in atmosphere will freeze on sealing surface, which will accelerate wear of friction pair of mechanical seal.
4.Friction and heat of sealing surface will cause sealed medium to vaporize, make friction pair of mechanical seal form dry friction, and burn the sealing surface.
5.Material expansion and contraction should be taken into account, and selected materials should have similar expansion coefficients.
These characteristics determine requirements and selection criteria for mechanical seals as follows: 1. When temperature of medium is higher than -45°C, a single mechanical seal can be used, but it is necessary to pay attention to freezing of moisture in atmosphere, which will cause the mechanical seal to fail.
2. When medium temperature is higher than -100℃, it can be sealed with bellows mechanical seal.Dry nitrogen is blown to sealing face to isolate the sealing face from atmosphere and prevent water molecules from freezing.
3.When medium temperature is lower than -100℃, static bellows structure is used to prevent the bellows from fatigue and damage.
4.Appropriate friction pair materials should be adopted, such as QSn6.5-0.1 bronze filled PTFE.
5. Mechanical seals with low end face specific pressure and low POV value should be adopted to strengthen quenching and flushing.
