8 Dimensioning pollution in exhaust gases
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Statutory Documents - IMO Publications and Documents - Circulars - Maritime Safety Committee - MSC/Circular.729 – Design Guidelines and Operational Recommendations for Ventilation Systems in Ro-Ro Cargo Spaces – (Adopted on 4 July 1996) - Part 1 - Design Guidelines and Operational Recommendations for Ventilation Systems in Ro-Ro Cargo Spaces - Appendix 1 - Ventilation of ro-ro cargo spaces - Requirements and basic calculations - 8 Dimensioning pollution in exhaust gases

8 Dimensioning pollution in exhaust gases

 Below are some examples of frequently occurring operating cycles and an average value of the quantity of pollution in exhaust gases produced by vehicles with internal combustion engines running in ro-ro cargo spaces.

Parent topic: Appendix 1 - Ventilation of ro-ro cargo spaces - Requirements and basic calculations

8.1 Ro-ro ships

 For loading and unloading of trailers from ro-ro ships, larger trucks and loaders are generally used. Type of engine: Turbo-charged diesel engine, approximately 150 kW.

The number of trucks operating simultaneously is highly dependent on the size of the ship, the number of decks, the design of the ramp and ease of access etc. are of great importance. A normal operating cycle for vehicles consists of lift (about 45s), transport and idling.

For the local vehicle handling on board ro-ro ships smaller diesel powered trucks are used as a rule. Type of motor: Suction fed diesel engine, approximately 74 kW.

The number of smaller trucks operating simultaneously is dependent on the size of the vehicle deck. A normal operating cycle for smaller trucks is short and consists of lift, transport and idling.

Exhaust gas generation from buses, lorries and passenger vehicles on ro-ro ships is comparable with the one for vehicles on ferries (see paragraph 8.2).

8.2 Ferries

 The vehicle mix on board ferries varies seasonally from the main part (70 - 80%) of the vehicle capacity being occupied by long-distance lorries and the rest by passenger vehicles, to the opposite proportions. For most of the year the former applies on most routes.

For passenger vehicles the cargo handling is quick. A vehicle deck with up to 300 cars can, if the traffic conditions are good, be discharged in 15 minutes. Such a quick discharging can mean that many vehicles may have their engines running at the same time during the discharging.

A normal operating cycle for passenger vehicles on board ferries consists of running at a low speed, acceleration, motor braking and idling.

  • Type of motor: Petrol engine 1,000 - 2,200 cm3.

A normal operating cycle for larger lorries and buses on board ferries consists of charging the compressed air system for the brakes, acceleration and running at a low speed.

  • Type of motor: Turbo-charged diesel engine, approximately 150 kW.

8.3 Car carriers

 On car carriers the cargo handling is normally carried out without any queuing. The turnover of the cargo is about 350 cars per hour. There are generally 6 - 10 cars in continuous operation and it can be supposed that 4 of them are on the vehicle deck.

A normal operating cycle for a passenger car on board car carriers consists of running at a moderate speed and a smaller part of idling.

  • Type of motor: Petrol engine 1,000 - 2,200 cm3.
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