As we know the sample vial is composed of mainly three parts, the bottle body, the cap, and the septa. Each of them plays an important role in the experiment and analysis. We have talked much about the bottle body, today we will discuss the most frequently used PTFE septa.
What are PTFE septa?
The PTFE septa is a polymer compound formed by the polymerization of tetrafluoroethylene. Its layout is simplified as -[-CF2=CF2-]n-. “Plastic King” is the common name of PTFE septa, which is a kind of plastic with good corrosion resistance. Even the powerful aqua regia is helpless to it, hence the name Plastic King.
In addition to molten sodium and liquid fluorine, all other chemicals in this field are widely used in various requirements for acid, alkali, and organic solvent resistance, airtightness, high smoothness, and non-stickiness, electrical insulation, outstanding anti-aging resistance, and excellent temperature resistance.
PTFE septa is also called Teflon speta. Flat septa, V-shaped septa, piston septa, ball valve septa have good characteristics such as corrosion resistance, aging resistance, and non-conductivity. The pH value of PTFE is 0-14 (except for molten alkali metals and fluorine under high temperature and high pressure). The PTFE septa is a clean sealing product, which will not pollute any substances it comes into contact with, and can be widely used in food, medicine, and other industries.
Advantages of PTFE Septa
1. Low temperature resistance-good mechanical toughness; even if the temperature drops to -196℃, it can maintain 5% elongation. 2. Corrosion resistance-It is inert to most chemicals and solvents and can withstand strong acids and alkalis, water, and various organic solvents. 3. Weather resistance-it has the best aging life among plastics. 4. High lubrication-it is the one with the low coefficient of friction among solid materials. 5. No adhesion-it is the small surface tension of solid materials and does not adhere to any substances. 6. Non-toxic and harmful-with physiological inertia, as an artificial blood vessel and organ implanted in the body for a long time, it will not bring any adverse reactions.
Use notes of PTFE Septa
1. The temperature of the place. The temperature will also directly affect the sealing performance of the PTFE septa, so the selection of materials must be equal to or higher than the temperature of the on-site working condition. For example, the mechanical strength of the pure PTFE septa is very stable even from minus 100 degrees Celsius to 100 degrees Celsius, but when the temperature is too low, the pure PTFE mat will become very brittle, so the temperature of the working environment is as good as possible. It may not fall below minus 185 degrees Celsius.
2. Material and performance characteristics of PTFE septa. PTFE septa are divided into two types: soft PTFE septa and hard PTFE septa. In general, the soft PTFE refers to the expanded PTFE septa, and the hard PTFE refers to the ordinary PTFE septa on the market. Both of these are good materials for making anti-corrosion gaskets. Performance is the key factor that determines the use occasion of PTFE septa.
Different septa materials have different corrosion resistance, heat resistance, density, etc., and their applicable sealing media and working conditions are different. For example, the soft PTFE septa are prone to elastic or plastic deformation under the action of preloading force, thereby blocking the fluid leakage channel, which is conducive to sealing, but soft PTFE materials generally cannot withstand the action of the high-pressure fluid.
3. Consider the medium that needs to be sealed PTFE septa can seal hot water, oil, acid, and other media. However, in order to have a better sealing effect, the material of the sealing gasket must be selected according to the temperature, pressure, PH value, acidity, and alkalinity of the actual sealing medium.