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Watchmen's Systems

Watchmen are used on vessels that are not required to have supervised patrols. At night, a suitable number of watchmen must be stationed in the passenger accommodation areas on each deck. The watchmen are under the direct control of the master or watch officer and must report to that officer at fixed intervals, not exceeding one hour.

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Automatic Detection Devices

Fires develop in four stages which include the incipient, smoldering, flame, and heat stages. Various types of detectors will respond to these different stages of fire. It is highly desirable to have detection equipment's respond to the incipient stage, which is that stage where no invisible products of combustion are evident. The most common type of detector in use today is the thermal type, which responds to the last, or heat stage.

When determining what detector should be utilized, the most important considerations are the following a) the energy levels which might be anticipated; b) the type of fire from the standpoint of quantities of smoke, which may be developed; c) and the rate of heat release. As an example, a thermal detector, which has rather slow response to many types of fire, if properly installed and positioned will respond rapidly to a high-energy-release fire such as created by ignition of flammable liquid vaporous. The same detector, however, could not be anticipated to respond to a low-energy fire such as might be expected in electronic equipment typically found in control rooms and data processing areas. While we have indicated that thermal detectors will respond to these high-energy-release fires, that is, the rapid reaching the flame stage, it should be added that more sophisticated (сложный) flame-response detection equipment will alarm more rapidly to this type of fire.

The general types of detectors, which are in common use:

Thermal type: respond to heat. Photoelectric or smoke detectors:

respond to visible smoke. Flame type: respond to the flame stage of fire. Products of combustion (lionization) type: respond to combustion particles.

There are interesting developments in detection in the field of aerospace industry, including line-type detector and semiconductor detector, both of which would be properly classified under the thermal type.

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