1. Monitoring Environmental Conditions for Cleaning & Painting Operations
This one-hour webinar describes the various procedures and instrumentation for monitoring environmental conditions and surface temperature prior to and during surface preparation and coating installation operations.
William D. Corbett
KTA-Tator, Inc.

2. Introduction Webinar Content:
Overview of Commonly Monitored Conditions during Surface Preparation
Overview of Commonly Monitored Conditions during Coating Work
Instrumentation for Measuring Environmental Conditions
Documentation of Conditions
Determining Conformance to Project Specifications and/or Manufacturer’s PDS
Location and Frequency of Data Acquisition
Altering the Environment to Achieve Conformance
During this webinar, I will be describing the purpose of SSPC’s Guide 15 on retrieval and analysis of soluble salts; showing a listing of ISO standards for extraction and analysis of soluble salts; describing various methods of surface extraction and analysis in the laboratory, shop or field, and a procedure for converting conductivity measurements to surface concentrations based on an assumption of the presence of sodium chloride.
What I will not be discussing in this webinar are the precise step-by-step instructions for the various methods of extraction and analysis. In fact, hands-on training with the various kits is probably the most effective way to become more comfortable with the procedures. Also, I will not be discussing the boiling extraction method described in Guide 15, as this is primarily a laboratory procedure. Finally, I will not be addressing the selection of sampling locations, the number of samples to collect or acceptable levels of soluble salt contamination.

3. Learning Objectives/Outcomes
Completion of this webinar will enable the participant to:
Describe the environmental conditions commonly monitored during surface preparation and coating work
Describe the instrumentation that is commonly used to measure environmental conditions
Document environmental conditions
Compare on-site conditions to specification requirements
Describe the frequency and location of measurements
Describe methods for altering the environment to attain conforming conditions
There are six learning outcomes or objectives for this webinar. Completing this webinar will enable you to:
Describe the environmental conditions commonly monitored during surface preparation and coating work
Describe the instrumentation that is commonly used to measure environmental conditions
Document environmental conditions
Compare on-site conditions to specification requirements
Describe the frequency and location of measurements, and
Describe methods for altering the environment to attain conforming conditions

4. Definitions Air Temperature (Ta) Wet Bulb Temperature (Tw)
Depression of Wet Bulb Temperature from Dry Bulb Temperature (Ta-Tw)
Relative Humidity (RH)
Dew Point Temperature (Td)
Surface Temperature (Ts)

5. Definitions Air Temperature (Ta): Temperature of the surrounding air
Wet Bulb Temperature (Tw): A measurement of the latent heat loss caused by water evaporation from a wetted sock on the end of a bulb thermometer in a psychrometer
Depression of Wet Bulb Temperature from Dry Bulb Temperature (Ta-Tw): The calculated difference between the air temperature and the wet bulb temperature

6. Definitions
Relative Humidity (RH): The percentage of moisture or water vapor in the air, relative to the maximum attainable at the same temperature
Dew Point Temperature (Td): The temperature at which condensation of water vapor occurs on a surface
Surface Temperature (Ts): The temperature of the surface to be prepared and coated

7. Converting Temperature
Temperature expressed in Celsius or Fahrenheit
Celsius
Freezing is 0; boiling is 100
Fahrenheit
Freezing is 32; boiling is 212

8. Converting Temperature
Converting Fahrenheit to Celsius
oC = (oF-32oF) ÷ 1.8
Example:
(83oF-32oF) ÷ 1.8 = 28.3oC
Converting Celsius to Fahrenheit
oF = (1.8 x oC) + 32oF
(1.8 x 5oC) + 32oF = 41oF

9. Environmental Conditions for Surface Preparation
“Rough” surface preparation work can occur when conditions are less than desirable (unless prohibited by contract)
“Final” surface preparation work should occur when conditions preclude moisture formation on prepared surfaces

10. Measuring Ambient Conditions Prior to Final Surface Preparation
If air temperature and relative humidity are such that moisture from the air condenses on the surface, the surface may rust bloom, or rust back prior to coating
Recommend verifying that the temperature of the surface is at least 5°F (3°C) higher than the dew point temperature to preclude condensation (requirement may be invoked by specification)

11. Significance of 5°F (3°C)
Theoretically, a small (<1°F) increase (surface temperature over dew point) will preclude moisture formation
Minimum increase of 5°F (3°C) compensates for:
Instrument tolerances
Varying conditions
Changing conditions

12. Environmental Conditions for Coating Application
Air Temperature (min. & max.)
Relative Humidity (min. or max)
Dew Point Temperature
Surface Temperature [min. 5 °F (3°C)] above Dew Point Temperature
Wind Speed (max.)

13. Significance of Conditions
Air Temperature
Too cold or too hot can affect coating application & curing
Relative Humidity
Too damp or too dry can affect coating application & curing
Surface Temperature
Too cold or too hot can affect application & curing
Surface temperature at or below dew point temperature will result in condensation

14. Significance of Conditions, con’t.
Wind Speed
Too windy can affect application (dry spray) and cause overspray damage
Mixing/application of coatings under adverse weather conditions can void the manufacturer’s warranty and is considered a specification non-conformance

15. History of Environmental Condition Measurement
Whirling apparatus containing wet & dry bulb thermometers developed in the 1600’s

16. We’ve Come A Long Way Baby!
Use of Sling psychrometers to obtain dry bulb/wet bulb measurements is still mainstream
Electronic measurement is possible
Some electronic psychrometers adversely affected by “outdoor” conditions

17. Ambient Conditions & Surface Temperature
Measuring Instruments
Sling Psychrometers*
Battery-powered Psychrometers*
Electronic Psychrometers
Analog, Thermocouple-type & Non-contact Surface Thermometers
* Used in conjunction with psychrometric charts or calculators

18. Sling Psychrometer

19. Using Sling Psychrometers
ASTM E337
Verify wick cleanliness
Saturate wick and/or fill reservoir with DI water
Whirl second intervals until wet bulb stabilizes (2 readings within 0.5o)
Record wet & dry bulb temperatures

20. Using Battery-Powered Psychrometers
ASTM E337
Verify wick cleanliness
Saturate wick
Operate until wet bulb stabilizes (2 readings within 0.5o; typically 2 minutes)
Record wet & dry bulb temperatures

21. Using Psychrometric Charts
Locate Chart (relative humidity or dew point)
Verify Barometric Pressure (e.g., 30.0 in.)
Intersect air temperature with wet bulb depression (Ta-Tw)

22. Determining Dew Point Temperature
Example:
Air temperature: 60°F
Depression wet bulb thermometer: 5°F
Dew Point temperature: 51°F

23. Determining Relative Humidity
Example:
Air temperature: 60°F
Depression wet bulb thermometer: 5°F
Relative Humidity: 73%

24. Relative Humidity and Dew Point Calculators
Convert oF to oC using right “window”
Align dry bulb & wet bulb temperatures (top of calculator)
Read Dew Point from upper “window”
Align dry bulb & dew point temperature (bottom of calculator)
Read %RH from lower “window”
2, 3 1
4, 5

25. Using the Psychrometer Slide Scale
Intersect air temperature and wet bulb temperature
Base of “Y” points to relative humidity
Cannot determine dew point temperature
White ink fades over time/usage (left image)

26. Electronic Psychrometers
Measure/Record:
Air Temperature
Surface Temperature (ST)
Relative Humidity
Dew Point Temperature (DP)
Spread between
DP and ST
Features
Auto-logging allows for automatic data collection
Magnetic surface probe
Data graphing and uploading using software
Audio/visual alarm

27. Electronic Psychrometers
Measure/Record:
Air Temperature
Surface Temperature (ST)
Relative Humidity
Dew Point Temperature (DP)
Spread between DP and ST
Features
Auto-logging
Integral magnets
Data uploading using software
Audio/visual alarm
BlueTooth® Data Output
Another model (right) offers infrared surface temperature

28. Measuring Surface Temperature
Dial-Type Thermometer
Position & stabilize for minimum of 2 minutes
Thermocouple-Type Thermometers
Stabilize quickly
Infrared (non-contact) thermometers
Watch distance

29. Assessing Wind Speed Analog wind meters Digital wind meters
Rotating Vane Anemometers
Air flow inside containment
Wind speed

30. Documenting Ambient Conditions and Surface Temperature
Data
Date
2/23/11
Time
1300 hours
Dry Bulb Temperature (DB)
16oC (60oF)
Wet Bulb Temperature (WB)
13oC (55oF)
Depression (DB-WB)
3oC (5oF)
Relative Humidity
73%
Dew Point Temperature
11oC (51oF)
Surface Temperature
15oC (59oF)
Wind Speed
11 km/Hr (7 mph)
Measurement Location
West side of tank, ground level

31. Verification of Accuracy - Thermometers
ASTM E 337
Remove wick from thermometer
Compare dry & wet bulb temperatures quarterly
Compare thermometers to a traceable thermometer in controlled environment at minimum of 4 temperatures annually

32. Calibration of Electronic Psychrometers
Some manufacturers provide “Calibration Kits”
Used to verify accuracy only
Annual calibration by the manufacturer or approved laboratory recommended

33. Verification of Accuracy – Surface Thermometers
No “Standard” method
Equipment manufacturers provide instruction
Surface probes integral to electronic psychrometers are calibrated by the manufacturer
Compare thermometers to “Traceable” thermometer in controlled environment

34. Determining Conformance to Project Specifications
Compare actual conditions to project specification requirements
Example:
Air temperature: oF
Relative humidity: < 85%
Surface temperature: oF and a minimum of 5oF higher than dew point temperature
Wind speed: < 15 mph

35. Determining Conformance to Product Data Sheets
Compare actual conditions to manufacturer’s recommendations
Example:
Air temperature: oF
Relative humidity: < 95%
Surface temperature: oF and a minimum of 5oF higher than dew point temperature
Wind speed: Typically not addressed

36. Location and Frequency of Data Acquisition
Dictated by where the work is being performed (e.g., inside vs. outside of a containment; balcony of elevated storage tank vs. ground level)
If interior, with ventilation in operation
Shops: Blast or Paint bay area
Frequency
Prior to final surface preparation
Prior to mixing of coatings
Four-hour data collection intervals is common
More frequent measurement if conditions are changing

37. Achieving Conditions by Changing the Environment
Heat
Dehumidification
Humidification

38. Achieving Conditions by Changing the Environment
Heat
Achieve & maintain temperature during application & cure
Indirect fired propane
AC powered equipment with thermostatic controls
Ventilation to exhaust solvent vapors is critical

39. Dehumidification
Dehumidification (DH) equipment removes air moisture, reducing opportunity for condensation
Conditions monitored using computer software (component to DH equipment) or by manual measurements
SSPC/NACE Joint Technical Report
SSPC-TR3/NACE 6A192, “Dehumidification and Temperature Control During Surface Preparation, Application and Curing for Coatings/Linings of Steel Tanks, Vessels and other Enclosed Spaces”

40. Dehumidification, con’t.
DH accomplished by:
Compression
Refrigeration
Desiccation (liquid or solid sorption)
Combination of methods listed
Refrigeration and desiccation (solid sorption) most common for field work

41. Dehumidification, con’t.
Refrigeration
Air cooled over refrigeration coils
Condensation occurs on coils and is collected
Dry air exits the DH system (at reduced temperature, humidity and dew point)
Source: SSPC-TR3/NACE 6A192

42. Dehumidification, con’t.
Desiccant
Air passed over/through granular beds or fixed desiccant structures
Desiccant (silica gel or lithium chloride) is active and dehydrated (low vapor pressure)
Desiccant absorbs moisture from air. Hydration reaction causes exothermic reaction (heated air), so may be used with refrigeration-type DH
Source: SSPC-TR3/NACE 6A192

43. Achieving Conditions by Changing the Environment
Humidification
May be required for moisture cure coatings
Moisture generated by wetting down floors or dampening the applied coating after initial drying

44. Summary During this webinar, we have:
Reviewed commonly monitored conditions during surface preparation and coating work
Described the instrumentation used to measure environmental conditions, including methods of calibration and accuracy verification
Illustrated documentation procedures
Described the importance of determining conformance to project specifications and/or manufacturer’s PDS
Described the location and frequency of data acquisition
Described three methods to altering the environment, in order to achieve conformance
In summary, we have:

45. Monitoring Environmental Conditions for Cleaning & Painting Operations
THE END
Thank you for attending his one-hour webinar on procedures and instrumentation for monitoring environmental conditions during cleaning and painting operations.