CEN/TS 45545-6 2009 Railway applications Fire protection on railway vehicles Part 6: Fire control and management systems CEN/TS 45545-7 2009 Railway applications Fire protection on
Principles
Only a single fire occurrence is taken into account, as accommodating multiple independent fires is deemed unnecessary The analysis begins with the assumption that the train is in its normal operational state.
NOTE "Normal operational state" means that the train is assumed to have no defects which affect its running capability at the start of the analysis
In defining requirements for running capability with a fire on board the train, the following must be considered:
Stopping a train is not inherently life-threatening, and similarly, halting a train due to a contained or extinguishable fire does not pose a significant risk Therefore, it is crucial to establish operational requirements specifically for fires that could lead to serious injuries or endanger lives.
Severe fire incidents, such as major arson or catastrophic equipment failures, can render train systems incapable of functioning In such extreme cases, it is impractical to establish requirements that ensure the train's operational capability However, implementing measures to mitigate the effects of less severe incidents can still provide benefits during the progression of a fire towards more extreme scenarios, even if these benefits are not quantifiable.
To effectively assess the practicability of fire response, it is essential to establish a classification system for fires Understanding the nature of a fire allows for informed decision-making, leading to the categorization of fires into three distinct types as outlined in section 3.1.
When analyzing fire sources, it's crucial to evaluate specific equipment, recognizing that a single piece can serve as both a fire source and a victim of fire Distinguishing between these two roles is essential for a thorough analysis.
Annex E shows the clauses relevant to specific system functions.
Fire Classification Scheme
Type 1 fires, as defined by Ignition Models 1-4 in CEN/TS 45545-1, Annex A, are not considered a significant risk for trains built to EN 45545 These ignition models are deemed too small to pose a threat, and therefore, fire development is unlikely.
Thus for Type 1 fires there are no running capability requirements
In a "no requirement" scenario, such as a fire within a small equipment case housing safety-critical signaling equipment, the fire is classified under CEN/TS 45545-1 Ignition model 4 Although this fire may lead to the failure of the signaling equipment and subsequently cause the train to stop, the overall fire hazard remains minimal This is primarily due to the protective containment of the case and the flame-retardant properties of the materials used within it, as outlined in CEN/TS 45545-2.
Type 2 fire events, including luggage fires, vandalized seat fires, diesel fires, and major arson incidents, pose significant risks to train systems However, their scale allows for the establishment of protective measures to ensure a defined level of operational capability.
Running capability is defined only in respect of:
– initial development phase of diesel (and other combustible fluid) fires (Fires are assumed to be either exterior or within a separate technical compartment);
– significant arson or accidental ignition of brought in material (for example luggage placed/stored in accordance with operational protocols);
Ignition Model 5 of CEN/TS 45545-1 is a Type 2 Fire and is defined as the Reference Type 2 fire profile (see 3.1.4)
For verification of compliance by test the fire profile shall be the Reference Type 2 fire; Ignition Model 5 of CEN/TS 45545-1 using the "Alternative Burner" (2.2 in ISO/TR 9705-2:2001)
For compliance verification through modeling, the fire profile must be either the Reference Type 2 fire or Ignition Model 5 as per CEN/TS 45545-1, or it can utilize the real fire profile obtained from tests In the context of seats, the fire profile generated from tests on vandalized seats (CEN/TS 45545-2) is applicable Additionally, for diesel fires, an actual diesel fire profile, including any relevant initial development phase of the incident, may be employed.
The required duration for running capability, referred to as the "relevant period of the incident," does not have to align with the duration of the Type 2 fire profile or any standard tests used for pass/fail criteria It is important to note that the reference Type 2 profile represents the maximum requirement to be considered.
Type 3 fires, characterized by severe arson attacks or catastrophic failures in fuel-related systems, pose a significant risk Due to their immense scale, it is impractical to establish requirements that would ensure operational capability, given the extensive impact on the vehicle.
To effectively manage the transition from a Type 2 fire to a Type 3 fire, it is essential to implement measures that address the temporary presence of Type 2 fire conditions While the strategies designed for Type 2 fires may provide some advantages in handling Type 3 fires, the extent of these benefits remains uncertain.
There are no running capability requirements; i.e none additional to those required by the included Type 2 fires as stated above, arising in respect of:
– high power electrical faults on circuits which are not locally protected, electrically and by other means, according to EN 45545
– fully developed diesel (and other combustible fluid) fires resulting from failed equipment.
Application
The application of running capability to assess compliance for Type 2 fires is grounded in the use of Figure 1 This flow chart serves as a guide for evaluating each system function Once all relevant system functions are individually assessed and confirmed to be compliant, the overall system is deemed compliant.
Users begin their assessment at "Start" on the flow chart, entering Decision Box 1 If the analysis shows that the system function is compliant with Decision Box 1, indicating that no Type 2 fire is possible, the path taken is "No" to the "Compliant" end box In this case, no further analysis is required for that system function regarding running capability.
"existence test" for a Type 2 fire and guidance as to how to carry out this "existence test" is given in 6.2 and specifically in Figure 2
If the system function does not meet the criteria in Decision Box 1, it moves to Decision Box 2 If compliant in Decision Box 2, it is marked as "Compliant," requiring no further analysis for running capability If not compliant, the process continues to Decision Box 3, and upon failure, it progresses to Decision Box 4 If still non-compliant, it ultimately reaches Decision Box 5.
Compliance with Decision Boxes 1-4 halts the process and confirms the acceptability of the system function in question If all system functions meet this criterion, the train is deemed suitable for operation on any applicable network.
At Decision Box 5, compliance for any system function is established only after failures at Decision Boxes 1-4 This compliance indicates that the train is deemed acceptable for operation solely on routes where the Tractive Effort calculation has been conducted and confirmed to meet compliance standards.
Finally, a "No" at Decision Box 5 for any system function determines that the train is not compliant
NOTE 1 Other than for Decision Box 5 the order of the Decision Boxes does not determine a "preferred" order or hierarchy of effectiveness
Can the system function be impacted by a Type 2 fire
Is there a compliant fire fighting system.
Is the individual system function compliant.
Does the system function form part of a compliant redundant array.
Does the degraded mode comply with the Tractive Effort requirements.
Yes Yes Yes Yes No
Figure 1 Decision box flow chart
The temperature and time profile experienced by the equipment during a Type 2 fire will vary based on the specific fire profile used and the installation conditions, which encompass design, materials, and fixings.
The heat output of the fire profile is influenced by various factors that impact the temperature at the equipment The temperature/time profile can be calculated using methods such as Computational Fluid Dynamics (CFD) or determined through experimental approaches.
Specific requirements
In the absence of a defined operational protocol, neither the ATP nor system-applied emergency braking shall be overridden for reasons associated with running capability under fire conditions
The battery supply to all battery-operated auxiliaries required for running capability shall provide sufficient power for a minimum period of 15 min
Fire fighting systems must be designed to ensure that the extinguishing agent does not contaminate other unaffected system functions, preventing additional ignition events that could compromise operational integrity It is crucial to select extinguishing media with low electrical conductivity, especially when there is a risk of contact with electric circuits essential for operational capability or that could pose further hazards if short-circuited.
For electrical installations equipped with automatic extinguishing systems, it is essential that the conductivity of the medium remains below 5 × 10^{-6} S·m^{-1} to prevent the risk of new ignition sources caused by short circuits during discharge.
The equipment involved in the fire fighting system discharge does not need to remain operational, as power to this equipment is typically cut off prior to the system's activation.
NOTE The intention is that the discharge does not cause problems with equipment which is not combusting
Transformers and inductances shall be type tested in accordance with EN 60310 The cooling medium shall be type K according to EN 60310:2004, 7.1.
Decision Box 1 - Existence of a Type 2 (or Type 3) fire
In deciding whether a Type 2 fire is possible (and can impact system function) all of the following sites/sources shall be considered:
– diesel fuel and other combustible fluids;
– brought in material; defined as luggage placed/stored in accordance with operational rules;
In deciding whether a Type 3 fire is possible (and can impact system function) all of the following sites/sources shall be considered:
– high power electrical faults on circuits which are not locally protected, electrically and by other means, according to EN 45545;
– fully developed diesel (and other combustible fluid) fires resulting from failed equipment
The methodology for assessment relevant to this Decision Box 1 is given in Figure 2 (Decision Box 1 flow chart)
This Decision Box aims to incorporate engineering judgment regarding the system's nature and function, as well as the characteristics and location of potential Type 2 fires, to assess, on a fail-safe basis, whether there is an impact on system functionality.
– Claims for compliance at the Decision Box 1 level for diesel or other combustible fluids shall not be permitted
Given that a Type 2 fire can impact a system function ("Yes"; Decision Box 1), it is required to consider the system function under Decision Box 2
Identify system functions relevant for running capability in accordance with the applicable regulation
Locate products and equipment relevant to the identified system functions
Locate Type 2 (and Type 3) fire sources
In areas equipped with diesel engines or high power equipment not locally protected, electrically and by other means, according to
Can the system function be impacted?
Luggage placed/stored in accordance with operational protocols
Vandalised seat on the floor in luggage stack in luggage rack on the seat
Figure 2 Decision box 1 flow chart
Insulation liquid cooled transformers or inductances that meet the criteria outlined in CEN/TS 45545-2 are not classified as sources of Type 2 or Type 3 fires, provided they adhere to the specified line current requirements.
To protect the transformer or the line inductance from internal failure there shall be:
– protection based on the rate of change of the primary current of the transformer (differential protection) and
– earth fault detection on the line inductance which cause the main circuit breaker to open
There shall be a protection device which causes the main circuit breaker to turn off the current in accordance with the over-current strategy of the traction control system function
In dual voltage traction systems operating on DC supply, it is essential to monitor the status of the AC main circuit breaker This ensures that if the breaker fails to disconnect the supply to the transformer, the pantograph will be automatically lowered Additionally, it is important to address overpressure issues in the transformer or inductance tank.
An over-pressure valve is essential for safeguarding the tank against rupture due to catastrophic internal failures The pressure setting for this valve must align with the tank's design specifications and undergo type testing Additionally, the outlet of the over-pressure valve should be positioned away from potential ignition sources.
An over-pressure switch will be installed to open the main circuit breaker upon activation This switch is designed to activate at a pressure level that ensures no fluid is released from the over-pressure valve during any non-catastrophic internal failures.
The overpressure valve shall be in accordance with EN 50216-5:2002/A2:2005, Clause 6
The activation pressure of the over-pressure switch is generally set to 0.2 bar lower than the pressure at which the over-pressure valve functions Additionally, monitoring the temperature and flow of the insulation liquid is crucial for system efficiency.
There shall be a means of monitoring the temperature and ensuring the flow of the insulation liquid
To ensure accurate measurement of insulation liquid temperature, it is essential to manage the power according to the temperature control strategy for the transformer or inductance, provided that the flow rate is adequate.
The temperature control strategy, including start up in cold temperatures, shall comprise:
– control of the tractive effort so the limit temperature of the insulation liquid is not exceeded, and
– isolating the transformer from the high power source if the temperature-rise limit of the insulation liquid is reached.
To ensure accurate measurement of insulation liquid temperature, it is crucial to maintain an adequate flow rate If the flow rate is insufficient, the power must be turned off by disconnecting the transformer from the high power source.
NOTE 2 The limit temperature and the temperature-rise limit are described in 8.2 of EN 60310:2004
1 Modifications to 6.2.2.1, Transformers and inductances, List Entry b)
Replace: b) Overpressure in the transformer or inductance tank:
An over-pressure valve is essential for safeguarding the tank against rupture due to catastrophic internal failures The pressure setting for this valve must align with the tank's design specifications and undergo type testing Additionally, the outlet of the over-pressure valve should be positioned away from potential ignition sources.
An over-pressure valve will be installed to activate the main circuit breaker This valve is designed to open at a pressure level that ensures no fluid is released during non-catastrophic internal failures.
The overpressure valve shall be in accordance with EN 50216-5:2002/A2:2005, Clause 6
The activation pressure of the over-pressure switch is generally set to 0.2 bar lower than the pressure at which the over-pressure valve activates This is particularly relevant in the context of overpressure within transformers or inductance tanks.
A protective device must be installed to prevent tank rupture due to catastrophic internal failures The operating pressure of this device should align with the tank's design specifications and undergo type testing Additionally, the outlet of the protection device must be positioned away from potential ignition sources.
A protection device must be installed that, when activated, will open the main circuit breaker This device should be designed to activate at a pressure level that ensures no fluid is released during non-catastrophic internal failures.
In case an overpressure valve is used, the overpressure valve shall be in accordance with
When utilizing an over-pressure valve, it is important to note that the activation pressure of the over-pressure switch is generally set to 0.2 bar lower than the operational pressure of the over-pressure valve.
2 Modification to 6.2.2.1, Transformers and inductances, List Entry c)
Replace: c) Temperature and flow monitoring of the insulation liquid:
Monitoring the temperature and flow of insulation liquid is essential If the flow rate is adequate for precise temperature measurement, power management should align with the temperature control strategy for the transformer or inductance.
The temperature control strategy, including start up in cold temperatures, shall comprise:
– control of the tractive effort so the limit temperature of the insulation liquid is not exceeded, and
Decision Box 2 - Individual system function
A system function may be affected by a Type 2 fire, necessitating an evaluation of its robustness against such impacts.
There are two routes to compliance:
– compliance by test or – compliance by assessment
If compliance can be shown under Decision Box 2 then the Tractive Effort available will be nominally
Compliance in respect of cables associated with the system function under consideration for running capability is assured if one of the following conditions is met:
– they achieve 15 min circuit integrity under EN 50200, EN 50362 or IEC 60331-3 (as appropriate);
– they are thermally protected such that the circuits relevant for running capability in the assembly achieve 15 minutes circuit integrity under EN 50200 or EN 50362 (as appropriate)
1 Modifications to 6.2.2.1, Transformers and inductances, List Entry b)
Replace: b) Overpressure in the transformer or inductance tank:
An over-pressure valve is essential for safeguarding the tank against rupture due to catastrophic internal failures The pressure setting for this valve must align with the tank's design specifications and undergo type testing Additionally, the outlet of the over-pressure valve should be positioned away from potential ignition sources.
An over-pressure valve will be installed to activate the main circuit breaker, ensuring that it opens at a pressure level that prevents fluid release during non-catastrophic internal failures.
The overpressure valve shall be in accordance with EN 50216-5:2002/A2:2005, Clause 6
The activation pressure of the over-pressure switch is generally set to 0.2 bar lower than the pressure at which the over-pressure valve functions This is particularly relevant in the context of overpressure within the transformer or inductance tank.
A protection device must be installed to prevent tank rupture due to catastrophic internal failures The operating pressure of this device should align with the tank's design specifications and undergo type testing Additionally, the outlet of the protection device must be positioned away from potential ignition sources.
A protection device will be implemented to automatically open the main circuit breaker upon activation This device is designed to ensure that, during non-catastrophic internal failures, no fluid is released, activating only at a predetermined pressure level.
In case an overpressure valve is used, the overpressure valve shall be in accordance with
When utilizing an over-pressure valve, it is important to note that the activation pressure of the over-pressure switch is generally set to 0.2 bar lower than the operating pressure of the over-pressure valve.
2 Modification to 6.2.2.1, Transformers and inductances, List Entry c)
Replace: c) Temperature and flow monitoring of the insulation liquid:
Monitoring the temperature and flow of insulation liquid is essential If the flow rate is adequate for precise temperature measurement, power management should align with the temperature control strategy for the transformer or inductance.
The temperature control strategy, including start up in cold temperatures, shall comprise:
– control of the tractive effort so the limit temperature of the insulation liquid is not exceeded, and
To ensure safety, it is crucial to isolate the transformer from the high power source when the insulation liquid reaches its temperature-rise limit If the flow rate is inadequate for precise temperature measurement of the insulation liquid, the power must be shut down by disconnecting the transformer from the high power source.
NOTE 2 The limit temperature and the temperature-rise limit are described in 8.2 of EN 60310:2004 with: c) Temperature and flow monitoring of the insulation liquid:
Monitoring the temperature and flow of insulation liquid is essential If the flow rate is adequate for precise temperature measurement, power management should align with the temperature control strategy for the transformer or inductance.
The temperature control strategy, including start up in cold temperatures, shall comprise:
– control of the tractive effort so the limit temperature of the insulation liquid is not exceeded, and
To ensure safety, it is crucial to isolate the transformer from the high power source when the insulation liquid temperature reaches its limit If the flow rate is inadequate for precise temperature measurement, the power must be shut down by disconnecting the transformer from the high power source.
NOTE 2 The limit temperatures are described in EN 60310:2004, 8.2
2 Modification to 6.2.2.1, Transformers and inductances, List Entry c)
Replace: c) Temperature and flow monitoring of the insulation liquid:
Monitoring the temperature and flow of insulation liquid is essential If the flow rate is adequate for accurate temperature measurement, power management should align with the temperature control strategy for the transformer or inductance.
The temperature control strategy, including start up in cold temperatures, shall comprise:
– control of the tractive effort so the limit temperature of the insulation liquid is not exceeded, and
To ensure safety, it is crucial to isolate the transformer from the high power source when the insulation liquid reaches its temperature-rise limit If the flow rate is inadequate for precise measurement of the insulation liquid temperature, the power must be shut down by disconnecting the transformer from the high power source.
NOTE 2 The limit temperature and the temperature-rise limit are described in 8.2 of EN 60310:2004 with: c) Temperature and flow monitoring of the insulation liquid:
Monitoring the temperature and flow of insulation liquid is essential If the flow rate is adequate for precise temperature measurement, power management should align with the temperature control strategy for the transformer or inductance.
The temperature control strategy, including start up in cold temperatures, shall comprise:
– control of the tractive effort so the limit temperature of the insulation liquid is not exceeded, and
To ensure safety, it is crucial to isolate the transformer from the high power source when the insulation liquid temperature reaches its limit If the flow rate is inadequate for precise temperature measurement, the power must be shut down by disconnecting the transformer from the high power source.
NOTE 2 The limit temperatures are described in EN 60310:2004, 8.2
Decision Box 3 - Redundant array system function
A Type 2 fire can compromise a system function, necessitating the evaluation of whether a redundant array exists that can sustain the system function despite partial compromises within the array.
In any claim for compliance for an array in respect of redundancy it shall be demonstrated that:
– each means by which the system function can be maintained is independent and
– at least one of the means by which the system function is maintained, continues to function under the impact of the Type 2 fire
To maintain the functionality of the unaffected sections of a redundant array, it is essential to isolate the affected components without triggering emergency brake activation.
An air reservoir essential for operational capability must function effectively throughout the duration of the incident This requirement is fulfilled if one of the following conditions is met:
– the reservoir is protected by a separate fire resisting barrier compliant with 6.3.2.3 The term
"separate" requires that the barrier does not form part of any pressurised element;
In the case of a Type 2 fire, tests or assessments confirm that the reservoir will either stay below its maximum working temperature or continue to function effectively for air storage.
NOTE 1 The maximum working temperature of certain types of reservoir are defined in EN 286-3 or EN 286-4
A Type 2 fire-induced failure in a compressed air consuming device, excluding the brake, will not impact the braking system or compromise the vehicle's operational capability.
Non-return ("check") valves are essential for maintaining proper separation between the brake system and other components Additionally, air chokes and diaphragms can effectively limit the rate of air loss.
In any operational mode, including degraded mode, if an incident lasts longer than 4 minutes, it is essential to assess the driver's environmental quality concerning their functionality The driver's environment may be compromised by smoke and toxic fumes from fires occurring outside the cab.
At least one of the following shall be demonstrated:
In areas adjacent to the cab where a Type 2 fire may occur, it is essential that smoke and toxic fume concentrations do not reach levels that could impair the driver's function for the duration of the incident, which should not exceed 15 minutes.
Openable windows in the cab ensure adequate fresh air circulation while in operation, preventing driver impairment caused by the buildup of smoke and toxic fumes during the incident, which can last up to 15 minutes.
The HVAC system plays a crucial role in maintaining a safe cab environment by controlling air quality and preventing the buildup of smoke and toxic fumes, thereby safeguarding driver functionality during critical incidents for up to 15 minutes.
– the cab is equipped with smoke hood(s) complying with EN 403 for the driver(s) (or a device offering at least equivalent protection) so that driver function is not impaired
NOTE Comments on fire barriers in this note are specifically applicable to the driver's cab only and not to passenger areas
To ensure the driver's operational capability, it is essential to protect them from fire hazards, including the effects of smoke and toxic fumes CEN/TS 45545-3 outlines requirements for fire barriers between the saloon and the cab, focusing on integrity and radiation However, it lacks specifications regarding the transfer of smoke and toxic fumes from the saloon to the cab, as well as emissions from the unexposed side of the barrier into the cab.
6.4 Decision Box 3 - Redundant array system function
A Type 2 fire can compromise a system function, necessitating the evaluation of whether a redundant array exists that can sustain the system function despite partial compromises within the array.
In any claim for compliance for an array in respect of redundancy it shall be demonstrated that:
– each means by which the system function can be maintained is independent and
– at least one of the means by which the system function is maintained, continues to function under the impact of the Type 2 fire
To maintain the functionality of the unaffected sections of a redundant array, it is essential to isolate the affected components without triggering the emergency brake.
At Decision Box 3, compliance with tests from sections 6.3.2.1 to 6.3.2.3 is typically not considered, as a redundant array would be unnecessary otherwise Consequently, compliance through assessment is the most probable approach at this stage, although a full-scale test remains a potential option.
There are two routes to compliance:
If compliance can be shown under Decision Box 3 then the Tractive Effort available will be nominally
To demonstrate compliance of a redundant array, a 1:1 scale test must be conducted with Reference Type 2 fire using the "Alternative Burner" as specified in ISO/TR 9705-2:2001 This test can be performed in a facility, provided that the test environment accurately reflects all relevant aspects of the installed condition.
Compliance for the system function under consideration for running capability by assessment requires that the temperature versus time profile caused by the chosen Type 2 fire:
– is demonstrated not to cause a loss of system function, during the relevant period of the incident
6.4.4.1 Diesel fuel and other combustible fluids
Decision Box 4 - Presence of a fire fighting system
After confirming that no redundant array is immune to a Type 2 fire, it is essential to determine if an effective fire fighting system is in place to extinguish the fire, thereby eliminating the risk of serious injury or loss of life.
A fire fighting system shall comprise both automatic detection and automatic discharge of an extinguishing medium
There are two routes to compliance for the fire detection system:
At Decision Box 3, compliance from sections 6.3.2.1 to 6.3.2.3 is typically not considered, indicating that a redundant array is unnecessary Consequently, compliance through assessment is the most probable approach at this stage, although a full-scale test remains a potential option.
There are two routes to compliance:
– compliance by test; or – compliance by assessment
If compliance can be shown under Decision Box 3 then the Tractive Effort available will be nominally
To demonstrate compliance of a redundant array, a 1:1 scale test must be conducted with the Reference Type 2 fire using the "Alternative Burner" as specified in ISO/TR 9705-2:2001 This test can be performed in a facility, provided that the test environment accurately reflects all relevant aspects of the installed condition.
Compliance for the system function under consideration for running capability by assessment requires that the temperature versus time profile caused by the chosen Type 2 fire:
– is demonstrated not to cause a loss of system function, during the relevant period of the incident
6.4.4 Specific Requirements 6.4.4.1 Diesel fuel and other combustible fluids
All fuel supply lines connecting the supply tank to the engine block, as well as all return fuel lines, must adhere to the standards outlined in section 6.3.2.3 due to the potential for Type 2 fire hazards in compliance claims.
For trains equipped with more than one pantograph either the requirements for the single pantograph case shall be met or the following general requirement applies:
In case one pantograph fails, it is essential to ensure that the other pantograph(s) and their related equipment can still provide the required tractive effort along with the train's control and safety functions.
In evaluating an auxiliary converter, it is essential to consider the switching function related to both the transitions between converters and the equipment necessary for operational capability supplied by these converters.
6.5 Decision Box 4 - Presence of a fire fighting system 6.5.1 General
After confirming that no redundant array is immune to a Type 2 fire, it is essential to determine if an effective fire fighting system is in place to extinguish the fire, thereby eliminating the risk of serious injury or loss of life.
A fire fighting system shall comprise both automatic detection and automatic discharge of an extinguishing medium
There are two routes to compliance for the fire detection system:
– compliance by test; or – compliance by assessment
An air reservoir essential for operational capability must function effectively throughout the duration of the incident This requirement is fulfilled if one of the following conditions is met:
– the reservoir is protected by a separate fire resisting barrier compliant with 6.3.2.3 The term
"separate" requires that the barrier does not form part of any pressurised element;
In the case of a Type 2 fire, tests or assessments confirm that the reservoir will either stay below its maximum working temperature or continue to function effectively for air storage.
NOTE 1 The maximum working temperature of certain types of reservoir are defined in EN 286-3 or EN 286-4
A Type 2 fire-induced failure in a compressed air consuming device, excluding the brake, will not impact the braking system or compromise the vehicle's operational capability.
Non-return ("check") valves are essential for maintaining proper separation between the brake system and other components Additionally, air chokes and diaphragms can effectively limit the rate of air loss.
In any operational mode, including degraded mode, if an incident lasts longer than 4 minutes, it is essential to assess the driver's environmental quality concerning their functionality The environment may be compromised by smoke and toxic fumes from fires occurring outside the cab.
At least one of the following shall be demonstrated:
In areas adjacent to the cab where a Type 2 fire may occur, it is essential that smoke and toxic fume concentrations do not reach levels that could impair the driver's function for the duration of the incident, which should not exceed 15 minutes.
Openable windows in the cab ensure adequate fresh air circulation while in operation, preventing driver impairment caused by the buildup of smoke and toxic fumes during the incident, which can last up to 15 minutes.
The HVAC system plays a crucial role in maintaining a safe cab environment by controlling air quality and preventing the buildup of smoke and toxic fumes, thereby ensuring driver functionality during critical situations, with a maximum operational duration of 15 minutes.
– the cab is equipped with smoke hood(s) complying with EN 403 for the driver(s) (or a device offering at least equivalent protection) so that driver function is not impaired
NOTE Comments on fire barriers in this note are specifically applicable to the driver's cab only and not to passenger areas