Application Engineers are the key points of contact between pipeline companies and customers. Because they are engineers, they interface with clients as regards filtration and separation equipment and use the data to create project proposals. Application Engineers also use their engineering expertise to determine equipment and sizing requirements by applying gas laws, pressure loss, flow, and velocity calculations. In addition to providing technical support to sales reps and managers, they function in a sales role and review and process customer applications in addition to specifications, drawings, and piping and instrumentation diagrams (P&IDs). They are also responsible for negotiating sales contracts.