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Oily-mist resistant filter, breathing apparatus comprising same, and method for removing granule solid and liquid aerosol from gas

A filter and aerosol technology, applied in the direction of chemical instruments and methods, respiratory protection containers, respiratory filters, etc., can solve problems such as improving the filter system, and achieve a safe breathing environment, pressure drop, and small pressure drop Effect

Inactive Publication Date: 2007-04-25
3M INNOVATIVE PROPERTIES CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

As mentioned above, increasing the filter thickness increases the size of the filter system, potentially restricting the wearer's movement in a limited area

Method used

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  • Oily-mist resistant filter, breathing apparatus comprising same, and method for removing granule solid and liquid aerosol from gas
  • Oily-mist resistant filter, breathing apparatus comprising same, and method for removing granule solid and liquid aerosol from gas
  • Oily-mist resistant filter, breathing apparatus comprising same, and method for removing granule solid and liquid aerosol from gas

Examples

Experimental program
Comparison scheme
Effect test

test approach 1

[0124] The discharge current of the unpolarized sample was measured starting from 25°C at a heating rate of 3°C / min. Two samples from the same fabric were subjected to the same test except that they were placed in opposite directions when the samples were placed between the electrodes. For cases where the sample is placed in an orientation that produces a positive discharge current at temperatures above about 110°C, the peak position of the sample is measured.

[0125] Using differential scanning calorimetry (DSC) at a heating rate of 10 °C / min, the melting temperature of the sample was determined, and the melting temperature was defined as the temperature in the second DSC heating cycle (that is, heating above the melting temperature, cooling and solidification sample, reheated) resulting in the largest peak observed for melting.

test approach 2

[0127] Test the sample according to TSDC Test Method 1 to determine the correct orientation of the sample. The sample is then placed in the Solomat TSC apparatus in an orientation that produces a positive discharge current at the lower peak temperature of TSDC Test Method 1.

[0128] The test was then conducted by polarizing the samples at 100° C. for 1, 5, 10 or 15 minutes in an electric field of 2.5 kilovolts / millimeter (kV / mm) in the apparatus described above. Still in the electric field, the sample was rapidly cooled (at the maximum cooling rate of the instrument) to -50°C. The electric field was removed and the sample was kept at -50°C for 5 minutes, then heated at a rate of 3°C / min while measuring the discharge current. A baseline was drawn based on the slope of the curve from 0 to about 30°C, and the half-peak width was measured to calculate the value of the half-peak width of each peak.

test approach 3

[0130] This method is the same as TSDC test method 2, except that a baseline is drawn between the minimum values ​​on both sides of the selected peak, and the charge density of the sample is calculated at each polarization time. If there is no minimum on the high temperature side of the peak, a baseline is drawn between the minimum on the low temperature side of the peak and the crossing point of the curve on the high temperature side of the peak or extrapolated to the crossing zero current point. The area under the peak was integrated to calculate the charge density.

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Abstract

A filter that includes a first electret filter layer through which an airstream first passes before encountering a second electret filter layer. The first filter layer exhibits nondecreasing removal efficiency and removes a majority of a challenge aerosol; whereas the second layer exhibits decreasing removal efficiency and has an initial quality factor greater than the first layer. Together, the first and second electret filter layers can provide a filter that exhibits a nondecreasing removal efficiency and a relatively low pressure-drop. The filter can provide nondecreasing removal efficiency and reduced pressure drop even though the second electret filter layer exhibits decreasing removal efficiency in contrast to the desired nondecreasing removal efficiency for the filter as a whole.

Description

technical field [0001] The present invention relates to a multilayer filter with no reduction in efficiency when challenged with oil mist aerosols. Background technique [0002] People who come into contact with air containing toxic or hazardous substances are often required to wear a respirator that covers the nose and mouth and filters the air before inhaling it. Respirator designs are specified by the National Institute for Occupational Safety and Health (NIOSH). NIOSH has developed standards for various removal efficiencies for respirators that come into contact with different pollutants. For example, it is stipulated that filter media used in environments where oil is present must meet standards for the efficiency of removing oil mist from dioctyl phthalate (DOP) suspension droplets. Since the removal efficiency may vary with load, the standard specifies the minimum removal efficiency for a fixed exposure to the aerosol. Respirator filter media removal efficiency gen...

Claims

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Application Information

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IPC IPC(8): B01D39/16A62B23/02B01D39/14B32B5/26
CPCY10T442/227B01D39/1623Y10T442/68Y10T442/2262B01D39/16
Inventor J·S·休伯蒂
Owner 3M INNOVATIVE PROPERTIES CO
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