The vent cap and internal wire screen are designed to protect the tank vent lines against intrusion and blockage. A normally closed poppet in the valve opens at a predetermined pressure or vacuum setting to allow the tank to vent. A Duratuff® composite body tested to the equivalent of 80 years of service in the most severe environment without leakage problems. ATEX Approved for flame arrestor applications.. Complies with NFPA 30 Requirements for venting gasoline vapors upward.