Chapter 6 Environmental Testing

Question 1

1. Identify some of the defects that can be caused by incorrect application temperatures.

Answer 1

• Blistering
• Pin holing
• Cratering
• Dry Spray
• Mud Cracking

Question 2

2. Describe relative humidity.

Answer 2

Relative humidity is a measure of the amount of moisture in the air compared to saturation level.

Question 3

3. What is the dew point temperature?

Answer 3

Dew Point is the temperature at which moisture begins to form on a steel surface.

Question 4

4. Name some of the effects wind may have on a coating project.

Answer 4

• Blow abrasives past the boundaries of the abrasive-blast work area to an area where coating are being applied
• Cause excessive drift or overspray of sprayed coatings
• Accelerates solvent evaporation after application
• Contribute to the formation of dry spray

Question 5

5. What are some of the common errors when using an electronic hygrometer?

Answer 5

Operator-based errors: the reading was taken in direct sunlight, the instrument was left in place too long, or removed before it stabilized
Equipment-based errors: calibration or equipment malfunctions

Question 6

6. Explain the process for use of the sling psychrometer.

Answer 6

To use the sling psychrometer:
• Saturate the sock with clean water.
• Whirl the instrument rapidly for about 40 seconds.
• Read the wet-bulb temperature.

Repeat the process (spin and read without additional wetting) until the temperature stabilizes