Most utilities target 20–25°C temperature, 40–60% relative humidity, and consistent air circulation to protect relay panels and communication equipment. Relay room cooling and environmental optimization focus on maintaining stable temperature, controlled humidity, proper airflow, and low electromagnetic interference. Place air conditioner inside protected area or in protected mechanical room, or if air handler must be placed outside of protected. The presence of water vapour in air is referred to as humidity and is defined in different ways: Absolute humidity (AH): The density of water vapour in air, typically expressed as grams/cubic meter [g/m3]. We draw from several Standards and discuss particulate and gaseous contaminants, plus address pressurization, filtration and air conditioning in one document as they all impact on the quality of the working environment.
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