Standard for Desiccant Dehumidification Components

ARI 940-98: Standard for Desiccant Dehumidification Components

Achieving precise humidity control is paramount in numerous industrial and commercial applications. For engineers and designers specifying desiccant-based systems, understanding the performance and rating of individual components is crucial. ARI 940-98, the "Standard for Desiccant Dehumidification Components," provides an essential framework for ensuring consistency, reliability, and accurate performance claims in this specialized field.

What is ARI 940-98?

ARI 940-98, published by the Air-Conditioning and Refrigeration Institute (ARI), establishes definitive guidelines for the testing and rating of factory-manufactured, thermally regenerated, dynamic desiccant dehumidification components. Its primary purpose is to ensure that manufacturers provide clear, comparable, and verifiable performance data for these critical components, enabling engineers to select and implement them with confidence.

Scope & Purpose

This industry-leading standard governs the performance characteristics of the desiccant-containing assembly itself, including its drive motor and integrated seals. It specifically addresses components designed for dynamic dehumidification processes where both sorption and desorption are aided by airflow, and the desiccant is thermally regenerated in situ. Excluded from its scope are liquid desiccant systems, regenerative heat exchangers (enthalpy wheels), and components intended for static or packaging applications.

Who Must Comply?

• • Primary audience: HVAC Engineers, Product Design Engineers, Test Engineers, Standards Developers, and Specifiers.
• • Industries affected: HVAC Manufacturing, Industrial Process Control, Building Services, Specialty Chemical Manufacturing, and any sector requiring precise humidity management.
• • Compliance nature: Voluntary, but essential for manufacturers seeking to provide credible, industry-recognized performance ratings.
• • Enforcement: Compliance is typically self-declared by manufacturers based on adherence to the standard's testing and rating procedures.

Key Requirements Overview

ARI 940-98 mandates a structured approach to component evaluation and communication. Key provisions include:

• • Defined Terminology: Establishes clear definitions for terms like "Moisture Removal Capacity (MRC)," "dynamic" processes, and "published ratings" to ensure universal understanding.
• • Standardized Testing: Requires testing to be conducted in accordance with ASHRAE Standard 139, utilizing specific process and regeneration air inlet conditions as outlined in Table 1 of the standard.
• • Performance Metrics: Dictates that Moisture Removal Capacity (MRC) be calculated based on specified inlet and outlet humidity ratios and airflow.
• • Rating Conditions: Specifies "Standard Rating Conditions" for consistent comparison of component performance across different manufacturers.
• • Data Transparency: Outlines minimum data requirements for published ratings, ensuring engineers receive comprehensive information for selection.

Related Standards & References

ARI 940-98 often works in conjunction with other foundational standards. ASHRAE Standard 139 ("Method of Testing Desiccant Dehumidifiers") is a critical reference for the actual testing procedures. Additionally, ARI Standard 430 ("Central Station Air-Handling Unit Systems") may be referenced for fan arrangement classifications, ensuring a holistic approach to system design. By adhering to these interconnected standards, professionals can confidently integrate desiccant dehumidification components into a wide range of HVAC and industrial air treatment systems.