Fire Suppression Systems Overview

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Questions and Answers

What action does the Manual Fire Suppression Actuator Valve perform?

Extinguishes fire in the engine compartment (correct)

Increases the fuel pressure

Releases gas into the atmosphere

Depletes gas from the fuel system

What is the function of the Internal Pressure Relief Devices (PRD)?

To stop gas from venting in case of over-pressurization

To increase fuel pressure during operation

To allow discharge of gas into the atmosphere when necessary (correct)

To contain gas leaks in the fuel system

What is the maximum fuel pressure for the bus model described?

3,600 psi (correct)

3,200 psi

3,000 psi

4,000 psi

What should you NOT do when observing gas venting from the roof outlets?

Attempt to stop the gas from venting Signup and view all the answers

How many fuel cylinders does model AN440 have in total?

10 or 11, depending on the model range Signup and view all the answers

What is the primary purpose of Pressure Relief Devices (PRDs) in the CNG gas system?

To vent excess fuel into the atmosphere Signup and view all the answers

What action should you take to disable the electrical power in a CNG-equipped vehicle?

Slide the battery disconnect switches to 'OFF' Signup and view all the answers

What does the manual fuel shut-off valve do in an emergency situation?

Stops the fuel flow to the engine Signup and view all the answers

What safety measure is advised when working around CNG gas systems?

Avoid working in poorly ventilated spaces Signup and view all the answers

Which component is responsible for stopping the engine during an emergency?

Engine Compartment Switch Box Signup and view all the answers

What still remains pressurized even after closing the manual fuel shut-off valve?

All of the above Signup and view all the answers

How does the fire suppression system typically engage?

Automatically activated by heat detection Signup and view all the answers

What is the function of the gas detector system in a CNG vehicle?

To detect dangerous levels of gas Signup and view all the answers

What is a crucial step to take when responding to a CNG bus incident?

Establish a safe zone at minimum 50 feet from the bus. Signup and view all the answers

Why is it important to eliminate ignition sources at an incident involving a CNG bus?

CNG is highly flammable and can ignite easily. Signup and view all the answers

What potential hazard does large volumes of CNG gas pose in confined spaces?

Displacement of oxygen leading to asphyxiation. Signup and view all the answers

What should first responders prioritize during the preliminary evaluation of a CNG bus incident?

Interviewing the bus operator or MTA field supervisor. Signup and view all the answers

What are pressure relief devices used for in CNG systems?

To relieve excess pressure safely to prevent explosions. Signup and view all the answers

Study Notes

Fire Suppression and Safety Equipment

Manual Fire Suppression Actuator Valve: Activates fire extinguishing agent in engine compartment by pulling safety ring and pressing the red "FIRE" button.

Roof Vent Outlets and Fuel System

Roof Vent Outlets: Located at the right rear of the bus, these outlets release gas when there's over-pressurization or excessive heat. No attempt should be made to stop gas venting.
Fuel Specifications:
- Model: AN440
- Fuel Cylinders: 10 total for models 4696-4700; 11 total for models 4723-4793
- Fuel Capacity: 13,400 cu. ft.
- Max Pressure: 3,600 psi.

Emergency Response Guidelines

CNG Bus Hazards: Risks include equipment malfunctions, collisions, and leaks which may lead to fire or explosion.
Approach Protocol:
- Use caution and recon the area.
- Eliminate all ignition sources; avoid traffic flares.
- Establish a safe zone at least 50 feet away, expanding as needed.
Preliminary Evaluation: Interview personnel on-site and conduct visual inspections. Though non-toxic, large volumes of CNG in confined spaces can cause asphyxiation.

Pressure Relief Devices (PRDs)

PRDs are located throughout the fuel system and automatically open to vent gas when design pressure or temperature is exceeded.

Emergency Operating Procedures

Engine Compartment Switch Box: To stop the engine, toggle the "Rear Engine Run" switch to the center or "OFF" position.
Manual Fuel Shut-Off Valve: Turn the black handle 90 degrees to stop fuel flow, though high pressure remains in the system.
Battery Disconnect Switch: Slide both switches to "OFF" to disable electrical power and shut off fuel solenoid valves, ensuring safety during emergencies.

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Description

This quiz covers the operation of manual fire suppression actuator valves, including how to effectively extinguish fires in engine compartments. It highlights key actions such as pulling safety rings and pressing activation buttons. Additionally, the quiz touches on the function of roof vent outlets in gas depletion.