NFPA Updated CFPS Exam Questions and Answers by bryson

The correct answer is B. In wide-open spaces, the sound pressure level (SPL) decreases by 6 decibels (dB) every time the distance from the source is doubled. This is known as the inverse square law of sound propagation, which states that the intensity of sound is inversely proportional to the square of the distance from the source.For example, if the SPL at 1 meter from the source is 100 dB, then the SPL at 2 meters from the source is 94 dB, and the SPL at 4 meters from the source is 88 dB123

25%

Explosions or fires from flammable gas or oil fuel vapor-air mixtures may be prevented by ventilation and controls that keep the flammable vapor content below 25% of the lower flammable limit (LFL) of the vapor-air mixture, according to the web search results. The LFL is the lowest concentration of a gas or vapor in air that can produce a flash of fire in the presence of an ignition source. Below the LFL, the mixture is too lean to burn. The LFL varies for different gases and vapors, and it is usually expressed as a percentage by volume of air at 25°C and atmospheric pressure. For example, the LFL of methane is 4.4%, which means that a mixture of methane and air with less than 4.4% methane cannot ignite. To prevent explosions or fires, the concentration of flammable gases or vapors should be kept below 25% of their LFL, which is equivalent to 1.1% methane in this case. Ventilation, natural or mechanical, is one of the methods to achieve this by diluting the flammable gases or vapors with fresh air.Controls, such as gas detectors, alarms, valves, and interlocks, are another method to monitor and regulate the flammable gas or vapor levels and prevent them from reaching dangerous concentrations1234

The minimum pipe diameter size for direct discharge of steam inside a water tank is 2 in. (50 mm), according to NFPA 13, Standard for the Installation of Sprinkler Systems. This is to prevent water hammer, noise, and vibration caused by the rapid condensation of steam when it contacts the water. The pipe should also be equipped with a check valve to prevent backflow of water into the steam source.References: NFPA 13, Standard for the Installation of Sprinkler Systems, 2023 Edition, Chapter 8, Section 8.16.4.5.3; NFPA Fire Protection Handbook, 21st Edition, Chapter 14, Section 14.3.4.2.

ANSI S1.4a

Sound meters used to test notification appliances in fire alarm systems shall comply with the standard ANSI S1.4a, Specifications for Sound Level Meters, Type 2 requirements, according to NFPA 72 2010, the National Fire Alarm and Signaling Code.This standard specifies the performance and accuracy criteria for sound level meters that are used to measure the sound pressure levels of audible signals in fire alarm systems1