An interactive method and apparatus are disclosed through which a fluid purification system operator inputs the system's parameters and the method then identifies one or more fluid purification equipment packages which will be optimized at the component level to the operator's specific requirements. The invention includes a relational database containing data on fluid purification equipment, the components thereof and ancillary equipment, and associated operational software to which the operator gains access through a computer and which then presents to the operator a series of questions relevant to gas purification equipment and system requirements. The questions are such that the responses elicited from the operator for each question determine what the successive questions will be and what optimal components will be identified. The software and databases may be in memory on the computer, embodied on CDs or DVDs run by the computer, or accessed through the Internet.