Instrument Hook Up Diagram is also called Installation drawing, specifies the scope of work between Mechanical and Instrumentation departments. It is a detailed drawing showing typical installation of an instrument in a correct manner so that the instrument operates properly and prevent issues which could potentially affect the measurement such as liquid trap in gas impulse. Instrumentation Construction Engineer has to review and verify certain important points before going for an Instrument erection. Instrument Hook Up Diagrams detail the accessory and tubing hookup for both process and field instruments based on the tag number. Material take off with part numbers, number of particular fittings, size, connection, material type, mounting type. The below diagram shows the required components and tubing for installation of a pressure gauge. The required parts are shown in the below table.
Hook-up drawing indicates tubing slopes, position of instrument in reference to process tapping point, scope break between instrument vs piping. Hook-up drawing also gives information the requirement of bulk material for each installation. It also details its specification size, type and material and the quantity. A good designer can also read whether the instrument tapped in gas service or liquid service.