The ACV-HF-EOSSV shall be a Ductile Iron Body and Cover design. The Valve shall have a resilient seal disc, guided top and bottom; Bottom guide will be vanes, sliding in a stainless steel seat arrangement, single seated line pressure operated, diaphragm actuated, pilot controlled, valve. The valve shall seal by means of a stainless steel seat. All parts are to be replaceable in the field without removing the valve from the line. All flange dimensions including face to face lengths shall conform to ISO Standards.