A pyrometer is an instrument for measuring temperatures too great for an ordinary thermometer. It is used to find the temperature of a fire. An important use of pyrometers is in checking the progress of a fire that cannot be seen, such as a fire that has been confined in a closed compartment or hold.
By taking readings at the same location at various times, one can tell if
the fire is gaining or lessening in intensity. By moving the pyrometer to different locations along a bulkhead or deck, you can determine if the fire is extending laterally.Pyrometers are attached to, or embedded in
either of two types of bases. The usual type base may be placed on the deck over the fire space. The magnetic type can be "slapped" onto the outside of a bulkhead of a burning space. A chain should be attached to the base of the pyrometer. It can be used to pull the instrument across a deck that is too hot for personnel. It is also useful in lowering the pyrometer into a hot area. A pyrometer can be useful in evaluating the success or lack of success when flooding a burning compartment with carbon dioxide. You should keep in mind that great patience is needed to successfully extinguish cargo hold fires with carbon dioxide. One cannot "take a peek" to see how things are going. Opening up would significantly dilute the extinguishing gas within the cargo compartment, which would destroying its effectiveness. Using a pyrometer and checking the variations in temperature should give you your information. A rising temperature after carbon dioxide has been introduced would indicate two possibilities:1) the amount of carbon dioxide introduced is insufficient and more is required, or
2) the carbon dioxide is not reaching the fire (directed to the wrong fire zone, a control valve is closed or malfunction of the system). A steady lowering of the temperature would indicate that the carbon dioxide has either extinguished the fire or has it under control. However, though a steady lowering of the temperature is observed or even if the temperature reading is down to 66°C (150°F) or less, these encouraging readings should not be interpreted as a signal to open the compartment. There should be no need to open a cargo hatch until port is reached. After all, the damage to the cargo has already been done by the fire.
