About Vacuum Pump O-Ring
Vacuum pump O-ring are critical to the success of any vacuum system, but unfortunately, they can lose their elasticity over time and crack, allowing air to seep into the vacuum chamber. Therefore, high-quality O-rings are the first choice.
| Рабочее давление | ≤40MPa |
| Температура | -200 to +260°C |
| Средний | Applies to virtually all liquids, gases and chemicals |
| Приложение | Suitable for sealing of food and pharmaceutical products |
| Характеристики | Harmless to the human body and can be sterilized; low friction and no adhesion effect |
Understanding Vacuum Pump O-Ring
Select the O-ring material for a specific location based on expected exposure to temperatures during operation. Teflon, fluoroelastomer and nitrile rubber are common general purpose types.
The O-ring will only work properly if it is free of debris, smooth, without scratches or cracks, round rather than flat, and fully lubricated. If the O-ring is exposed, such as when opening or closing the front door of a single-chamber vacuum furnace, it will need to be wiped clean before each run.
If you wear tight-fitting latex gloves and carefully slide your fingers over the surface of an O-ring, you can easily detect small particles or defects on its surface. You should wipe the O-ring with a clean soft cloth and some rubbing alcohol, and apply a very light coat of high-quality vacuum grease to ensure a better seal.
O-Ring Failure
O-ring seals often fail prematurely in an application due to improper material selection or design. From an end user perspective, seals can fail in three general ways:
1. Appearance change.
2. Pollution.
3. Water leakage.
Influencing factors are stresses caused by vacuum or pressure and stresses caused by heat. Elevated temperatures can cause vacuum pump O-ring to degrade, outgas, or expand. Vacuum or pressure environments, or changes in between, can cause weight loss and deflation.
Vacuum pump O-ring failures can be divided into the following categories
■ Wear: Loose debris and particles are often found on the surface of a seal, either on a portion of the seal or with the plane of the seal itself parallel to the direction of motion. Contributing factors may include excessive temperatures, poor elastomer surface finish, rough sealing surfaces, dynamic motion, and processing environments containing abrasive particles.
■ Flattening: The cross-section of the seal is flat and its flat sides correspond to the mating surface of the seal. Factors causing this include excessive temperatures, excessive compression, improperly cured elastomers, and excessive volume expansion.
■ Degradation: Vacuum pump O-ring appear pits, cracks, blisters, voids or pockmarks on the surface. Absorption of gas at high pressure and subsequent rapid decompression. As the pressure is quickly removed, the absorbed gas forms bubbles and ruptures the surface of the elastomer. Factors contributing to this include low modulus or hardness elastomers, rapid changes in pressure, and incompatibility with vacuum, pressure, or thermal environments.
■ Extrusion: The low-pressure side of the seal develops a jagged edge that looks ragged. Factors that can cause this condition in vacuum pump O-ring include excessive pressure, excessive gaps, excessive gland filling, low modulus or hardness elastomers, incorrect size selection, sharp and irregular gland edges.
■ Installation damage: Small cuts, cracks or chips may appear on part of the vacuum pump O-ring or on the seal itself. Factors that contribute to this include incorrect tooling, poor technique, incorrect dimensions of the elastomer, sharp edges on the component or gland, contamination of the elastomer surface, and low modulus or hardness elastomers.
■ Thermal degradation: Vacuum pump O-ring may begin to develop radial cracks on the highest-temperature surfaces. Some elastomers may also show signs of softening due to excessive temperatures, i.e. a shiny surface. Factors causing this include excessive temperature excursions, the thermal properties of the elastomer, or cycling.
■ Others: The spiral is broken, so that the seal shows spiral marks or cuts on the circumference. Factors that contribute to this include low modulus or hardness elastomers, slow reciprocation speeds, tight or difficult installation, excessive gland width, irregular O-ring surfaces, insufficient lubrication, and rough or irregular gland surfaces.
At present, most sealing methods used by vacuum pump O-ring are rubber seals, viscose machine seals, magnetic fluid seals, and metal seals. Rubber seals mainly appear in the form of O-rings. O-rings have a long history and are widely used in the sealing of vacuum obtaining equipment due to their simple structure, convenient disassembly, low friction resistance and the absence of periodic adjustments. Even vacuum pump oil mist filters are sealed this way.
