... 1.Introduction: (1) Defination : LLT series dual spiral rotor engine oil , heavy oil , flowmeter is a highly accurate metrological instrument to measure ... ,(2) Instructure : Composed of measuring body, a pair of spiral rotor, transmission components and registry unit.(3) Advantage :High accuracy, large ... according to customers’ optionTechnical standard: JB/T9242-1999 positive displacement flowmeter.