CFPS Exam Question Example -operating principles can be used in a gas-sensing fire detector

 

 

CFPS Exam Question Example 

 Which operating principles can be used in a gas-sensing fire detector or a combination (multisensor) detector ?

A)      Semiconductor, catalytic element, or infrared absorption.

B)      Spot type, beam type, or air sampling type.

C)      Heat type, ionization type, or dual-sensor type.

D)      Optical type, thermal type, or particle type.

 

Answer: A) Semiconductor, catalytic element, or infrared absorption.

Section 14 

CHAPTER 2 ■ Automatic Fire Detectors 14-23

GAS-SENSING FIRE DETECTORS

Many changes occur in the gas content of the environment during a fire. It has been observed that detectable levels of gases are reached after detectable smoke levels and before detectable heat levels. One of three operating principles, that is, semiconductor, catalytic element, or infrared absorption, may be used in a gas-sensing fire detector or in a combination (multisensor) detector.

 

CFPS Exam Question Example : Which types of detectors are used to sense radiant energy emitted from combustion reactions?

CFPS Exam Question Example 

    Which types of detectors are used to sense radiant energy emitted from combustion reactions?

 

A)      Flame detectors and spark/ember detectors

B)      Smoke detectors and heat detectors

C)      Carbon monoxide detectors and gas detectors

D)      Motion detectors and occupancy sensors

 

Answer: A) Flame detectors and spark/ember detectors

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Section 14

CHAPTER 2 ■ Automatic Fire Detectors 14-23

RADIANT ENERGY–SENSING FIRE DETECTORS.

Radiant energy–sensing devices sense the radiant energy (electromagnetic radiation) emitted as a by-product of the combustion reaction, which obeys the laws of optics. This includes radiation in the ultraviolet, visible, and infrared portions of the spectrum, emitted by flames or glowing embers. They are categorized as flame detectors and spark/ember detectors.

CFPS Exam Example question - Which of the following statements is true about UV detectors used for fire detection?

 

CFPS Exam Question Example 

Which of the following statements is true about UV detectors used for fire detection?

A) UV detectors are not sensitive to hydrocarbons or metals.

B)  UV detectors are sensitive to all types of fires except hydrocarbons.

C) UV detectors are sensitive to most fires, including hydrocarbons, ammonia, sulfur, hydrogen, hydrazine, and metals

D) UV detectors are not effective in detecting fires caused by middle and heavy fraction petroleum distillates.

Answer: c) UV detectors are sensitive to most fires, including hydrocarbons, ammonia, sulfur, hydrogen, hydrazine, and metals.

SECTION 14 

14-24 SECTION 14 ■ Detection and Alarm

Flame Detectors.

Ultraviolet Flame Detectors. 

The ultraviolet spectrum comprises wavelengths ranging from approximately 0.1µm to 0.35µm.  UV detectors typically use a vacuum photodiode Geiger-Muller tube to detect the ultraviolet radiation that is produced by a flame. The photodiode allows a burst of current to flow for each UV photon that hits the active area of the tube. When the number of current bursts per unit time reaches a set level, the detector initiates an alarm. A special control unit is required to monitor the count rates from UV detectors and initiate alarm.

UV detectors are sensitive to most fires, including hydrocarbons (liquids, gases, and solids), ammonia, sulfur, hydrogen, hydrazine, and metals such as magnesium. However, the smoke produced by combustion of middle and heavy fraction petroleum distillates is highly absorptive in the UV end of the spectrum, and this must be compensated for in system design if UV detectors are used

 

جدار الحريق فى الاسقف المائلة

جدران الحريق فى الاسقف المائلة

لضمان تحقيق الهدف من جدران الحريق يجب تحقيق بعض الشروط فى الاسقف المائلة مع بعض المتطلبات.

المتطلبات :

عندما تكون السقف من جهة واحدة أو كلا الجهتين لجدار الحريق مائلة نحو الجدار الحريق بميل يتجاوز 2 وحدة عمودية في 12 وحدة أفقية (2:12)، فيجب تحقيق بعض المتطلبات و هى تمديد جدار الحريق.

تمديد جدار الحريق بالطريقة التالية :

قياس ارتفاع السقف الموجود على بعد 1200 مم (1.2 متر) من جدار الحريق. إضافة 750 مم (0.75 متر) إلى هذا الارتفاع. يجب أن يمتد جدار الحريق إلى هذا الارتفاع المحسوب. ومع ذلك، إذا أسفر هذا الحساب عن ارتفاع أقل من 750 مم، فإن جدار الحريق يجب أن يمتد على الأقل إلى ارتفاع 750 مم.

المرجع:
1- الكود السعودى 201 : 706.6.2 Buildings with sloped roofs

Requirements for Fire Wall Extension in Buildings with Sloped Roofs

Introduction

Fire Wall Extension in Buildings with Sloped Roofs.

Requirement :

When the roof on one side or both sides of the fire wall slopes towards the fire wall at a slope greater than 2 units vertical in 12 units horizontal (2:12), certain requirements need to be met.

Extension of the Fire Wall

The fire wall needs to extend to a certain height to effectively contain a potential fire. This height is calculated as follows:

1.    Measure the height of the roof located (4 ft.) 1200 mm (1.2 meters) from the fire wall.
2.   Add (30 in.)750 mm (0.75 meters) to this height.
3.  The fire wall should extend to this calculated height.
4.  However, if this calculation results in a height less than (30 in.)750 mm, then the fire wall should still extend to a minimum height of (30 in.) 750 mm.

In essence, the regulation ensures that the fire wall extends to a sufficient height to properly contain any fire that might occur in buildings with sloped roofs, based on the slope of the roof and its proximity to the fire wall.

Reference :

2021 International Building Code (IBC)-706.6.2Buildings with sloped roofs.

SBC 201-2018: 706.6.2 Buildings with sloped roofs