Calculating Thickness of PTFE Membrane Air Filter

In summary, the conversation discusses a method for determining the thickness of an exposed PTFE membrane air sampling filter. The initial thickness of an unexposed filter is given as 40μm. The conversation then mentions 5 ambient air exposed filters with varying mass concentrations and a procedure involving a constant light source and light sensor. The equation I1d12 = I2d22 is suggested as a possible solution, but there are questions about the saturation of the membranes, linear scaling of light transmittance, dimensions of the filters, and sources of error in the measurements. It is also noted that this is for research rather than a homework problem.
  • #1
laramman2
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Homework Statement


Is there any way we can measure the thickness of an exposed PTFE membrane air sampling filter? An unexposed filter (from the filter datasheet) has a thickness of 40μm. We have 5 ambient air exposed filters with the following mass concentrations: 1μg/m3 (filter 1), 20.1 μg/m3 (filter 2), 40.6 μg/m3 (filter 3) , 60.1 μg/m3 (filter 4) , and 66.1 μg/m3 (filter 5) . Also, for each filter, we performed a procedure where we transmit a 1460 lux constant light source through the filter and the reduced light intensity was captured by a light sensor. The data for that procedure are as follows:

CONTROL - 1460 LUX
FILTER 1 - 418 LUX
FILTER 2 - 375 LUX
FILTER 3 - 295 LUX
FILTER 4 - 185 LUX
FILTER 5 - 130 LUX

Btw, this is for our research. We try to determine the attenuation coefficient of each filter.

Thank you very much!

Homework Equations



I1d12 = I2d22

The Attempt at a Solution


Does the above equation possible to use?
 
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  • #2
Lots of questions about this one. Are the membranes saturated? Are you assuming linear scaling of light transmittance to thickness? Are the filters the same length and width in dimension? How does light attenuation scale with thickness of unsaturated membranes? How does light transmission vary in saturated vs unsaturated samples? Is the light absorbed differently for saturated vs unsaturated at that particular wavelength? Is it a single wavelength source?
What sources of errors are in your measurements?

Finally, this section is for homework problems. If this is for research then the Faq states this is not the place to put this question.
 

What is the purpose of calculating the thickness of a PTFE membrane air filter?

The thickness of a PTFE membrane air filter is an important factor in its performance and efficiency. By accurately calculating the thickness, we can determine the optimal conditions for air filtration and ensure that the filter is able to effectively remove particles and contaminants from the air.

How is the thickness of a PTFE membrane air filter calculated?

The thickness of a PTFE membrane air filter is typically measured using a micrometer. This instrument allows for precise measurements of the filter's thickness, which is usually expressed in microns (μm). The thickness can also be calculated by dividing the total weight of the filter by its surface area.

What are the factors that affect the thickness of a PTFE membrane air filter?

The thickness of a PTFE membrane air filter can be influenced by various factors, such as the type and quality of the PTFE material, the manufacturing process, and the intended use of the filter. Other factors that can affect the thickness include temperature, humidity, and exposure to different types of contaminants.

Why is it important to maintain a consistent thickness in PTFE membrane air filters?

A consistent thickness in PTFE membrane air filters is crucial for ensuring that the filter is able to effectively remove particles and contaminants from the air. A variation in thickness can lead to uneven filtration and reduce the overall efficiency of the filter. It can also affect the air flow and increase the pressure drop, which can impact the performance of the filtration system.

How can the thickness of PTFE membrane air filters be optimized for specific applications?

The thickness of PTFE membrane air filters can be optimized for specific applications by adjusting the manufacturing process and the type of PTFE material used. The optimal thickness will vary depending on the size and type of contaminants that need to be filtered, as well as the desired air flow and pressure drop. It is important to carefully consider these factors in order to achieve the best results for a particular application.

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