scope:

Introduction

The use of dehumidification and temperature control during surface preparation and coating/lining application can be beneficial in a variety of ambient conditions. When used properly, dehumidification (DH) provides air dew points well below the surface temperature and reduces the relative humidity (RH) at the surface. Reducing the RH at the surface can retard rust bloom.

The health and safety of personnel is also a factor in the design of a dehumidification system. Dehumidification equipment that is properly sized for a given space provides air flow for safe working conditions. The lower explosive limits (LELs), toxicity levels, and oxygen levels are all evaluated at each stage of the project.

The volume of coating to be sprayed per hour and the percentage of solvent and solids to be added is calculated using manufacturers' data sheets. The formulas for these calculations can be found in NFPA⁽¹⁾ 33.¹ The appropriate air-flow rate of the dehumidified and of the exhausted air through the enclosure and the proper instrumentation to be used for monitoring during both stages of the project are also determined.

⁽¹⁾ National Fire Protection Association (NFPA), P.O. Box 9101, Quincy, MA 02269-9101.