Standard Practice for Sampling for Particulate Contamination by Tape Lift

Importancia y uso:

3.1 The tape lift provides a rapid and simple technique for removing particles from a surface and determining their number and size distribution.

3.2 By using statistically determined sample size and locations, an estimate of the surface cleanliness level of large areas can be made. The user shall define the sampling plan.

3.3 The sampling plan shall consider the importance of surface geometry and surface orientation to gas flow, gravity, obstructions, and previous history of hardware. These factors influence particle fallout and entrapment of particles on the surface. The geometry of joints, recessed areas, fasteners, and the correspondence of particle-count data to area can be maintained.

3.4 The selection of tape and the verification of its effect on the cleanliness of the hardware is very important. The tape adhesive should have sufficient cohesion to avoid transfer of the adhesive to the surface under test. The impact of adhesive transfer should be evaluated by laboratory testing before using the tape on the hardware. Since potential for adhesive transfer exists, cleaning to remove any adhesive might be required. In addition, the tape should have low outgassing characteristics, and as a minimum, it should meet the requirements of less than 1.0 % total mass loss (TML) and 0.1 % collected volatile condensable materials (CVCM), as measured by Test Method E595.

3.5 Care should be exercised in deciding which surfaces should be tested by this practice. The tape can remove marginally adhering paint and coatings. Optical surfaces should not be tested until verification has been made that the surface coating will not be damaged. The minimum effectiveness of particle removal from smooth surfaces and angles down to 90° for all practice methods is 90 % for particles larger than 5 μm. Rough surface finishes result in low removal efficiencies. Surface finishes up to approximately 3.20 μm (125 μin.) have been tested and found to give satisfactory results.

3.6 This practice has been tested only on surfaces at room temperature. Evaluation of temperature effects must be conducted prior to using the test on surfaces other than room temperature.

3.7 Only personnel experienced in microscopic particle-counting techniques should be used to count and size the particles.

Subcomité:

E21.05

Referida por:

E2352-19, E2312-11R19, D7602-11R17, D7659-21, E2088-06R21, E1548-23, E2217-12R19, F0051_F0051M-20

Volúmen:

15.03

Número ICS:

49.040 (Coatings and related processes used in aerospace industry), 49.140 (Space systems and operations)

Palabras clave:

particulate contamination; pressure-sensitive tape; sampling;