Pirobloc offers you the most common instrument abbreviations used on PID of Heat Transfer Fluid Technology.
In engineering projects and P&ID involved on thermal fluid circuits, symbols like TT, TIT, TCV are frequently mentioned. These corresponds to Temperature Transmitter, Temperature Indicator Transmitter, Temperature Control Valve for example, according to ISA Standard S5.1. International Society of Automation.
As attached file you will find the right description of every single term.
Equally you can find also the correct graphic symbol of these instruments.