Transportation:

Transportation time is time needed to carry a change in a process variable from one point to another in the process. If the temperature of the lube oil is lowered through increasing the cooling water flow rate, a few time will elapse before the lube oil travels from the lube oil cooler to the temperature transmitter. The transportation time will increase if the transmitter is moved farther from the lube oil cooler. This time lag is not only a slowing down or retardation of a change; it is an actual time delay during that no change occurs.