It is important to drain an hot oil heater prior to attempting a radiographic inspection, because
a) oil and coke appear similar on the x-ray picture
b) oil and coke give a similar sound when the tube is hammered
c) x-rays passing through the oil might cause an explosion
d) drained tubes are cleaner for the radiologist to work with
e) it is safer
Hot oil high temperature (TSDH1) shutdown switches are installed on
a) the fuel gas line
b) the inlet line of the oil heater
c) the suction line of the pump
d) the surge tank suction line
e) the outlet line of the heater