Bell & Gossett A-3 Relief Valve, rated at 30 lbs (H48), is a safety valve that releases excess pressure from a system to prevent overpressure damage. It opens at the preset pressure to vent fluid and then reseals once pressure drops. The A-3 designation identifies this exact model within Bell & Gossett's range, making it the correct choice when a system design specifies an A-3 relief valve with a 30‑lb rating.
