Stainless Steel vs PTFE Impellers: Which is Right for Your Lab?
Impellers are a critical component of many laboratory processes, from biotechnology and pharmaceuticals to food and beverage production. When it comes to choosing the right impeller for your application, there are a number of factors to consider, including whether to use PTFE or stainless steel impellers.
PTFE, or polytetrafluoroethylene, is a synthetic fluoropolymer known for its exceptional chemical resistance and non-stick properties. Stainless steel, an alloy of iron, chromium and/or nickel, and other elements, is a common material choice for mixing impellers due to its durability and strength. Stainless steel impellers are most commonly used, more widely available, have more style and size options, and are cheaper than equivalent versions in PTFE. However, the unique properties of PTFE may justify the additional cost and effort to source. Let’s take a closer look at some of the key differences to help you determine which material is right for your lab.
Chemical Resistance
One of the biggest advantages of PTFE impellers is their exceptional chemical resistance. PTFE is resistant to a wide range of chemicals, including acids, bases, and organic solvents. This makes PTFE impellers an excellent choice for applications involving harsh chemicals or corrosive materials. Caframo offers several PTFE impellers, the A180, A183, and A185, which are designed to provide excellent chemical resistance and non-stick properties.
Stainless steel impellers, while generally durable, may not be the best choice for applications involving corrosive materials. Stainless steel can be corroded by certain chemicals (for example chlorine) and acids (like sulfuric acids), which can compromise the integrity of the impeller over time. Stainless steel exposed to these substances can deteriorate, risking exposure to metal contaminants leaching into your mixture.
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Strength and Durability
Stainless steel impellers are known for their strength and durability. Stainless steel is a strong, hard material that can withstand high-speed mixing and other demanding laboratory applications. Additionally, stainless steel is resistant to wear and tear, which means that it can be used for many years without needing to be replaced. Caframo offers a range of stainless steel impellers, including the A541, A190, and U044 which are designed to provide excellent durability and performance in a variety of laboratory applications. Stainless steel has excellent resistance to heat, and a much higher melting point.
PTFE impellers, while generally strong and durable, may not be as robust as stainless steel impellers. PTFE can be susceptible to wear and tear over time, especially when used in high-speed mixing applications or with abrasive materials. PTFE also has a lower melting point, becoming compromised around 500 °F (260 °C) – though most applications will not reach these temperatures.
It is worth noting that both PTFE and stainless steel impellers are suitable for sterilization in an autoclave.
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Non-Stick Properties
One of the most notable properties of PTFE is its non-stick surface. PTFE is known for its ability to repel substances, which means that it is less likely to accumulate buildup or residue over time. This makes PTFE impellers an excellent choice for applications where cleanliness and flow are critical. This aspect is especially relevant when formulating sticky substances, like adhesives and polymers.
Stainless steel impellers, while generally easy to clean and maintain, may not have the same non-stick properties as PTFE impellers. Stainless steel impellers may be more prone to buildup or residue, which can cause complication in mixing when working with moderate to highly adhesive compounds.
Please don’t hesitate to reach out to our mixing experts if you would like advice on your next mixing system!
