4. Vestigios de los cuentos de hadas
4.3 La ambientación medieval
a. Where the cooling load on any ATU can vary significantly, either in the short term, due to the movement of personnel or change in equipment status, or in the long term, due to changes in climate, controls are to be provided at the ATU that will allow the cooling performance to be matched to the compartment conditions.
b. The required control is to be achieved by restricting:
(1) The flow of CW through the cooling coil;
or
(2) The flow of cooled air to the compartment(s) using variable volume fans;
or
(3) A combination of both options.
c. Where control is achieved by restricting the air flow, care is to be taken that the minimum velocity across electrical heaters is maintained to avoid constantly tripping and that with compartments fully manned, the CO2 content of the air does not rise above permitted maximum levels.
d. Reduction in CW flow is to be achieved by fitting thermostatically controlled, three way, diverter valves in the ATU control panel (See Section 6).
e. Details of main heater controls are given in Section 8.
5.7 Special Requirements
5.7.1 Operational Spaces
a. These essential spaces are to be airconditioned with open recirculation back to an ATU. The fresh air requirement is to be trunked to the ATU and the requirements of Clause 5.6.a considered.
b. Supply terminals giving directional control of the air flow are to be sited at manned positions with diffusers or similar terminals positioned to disperse heat from equipments.
c. To prevent smoke entering selected Essential compartments in a fire situation, a positive pressure of 1 to 1.5 mbars relative to the surrounding spaces is to be maintained. Non return air bleed valves can be fitted to the recirculation grilles and shut off features incorporated on the ATU supply system serving the compartment to restrict smoke entry when the fans are stopped.
5.7.2 Accommodation and Recreation Spaces
a. These spaces are to be airconditioned with open recirculation back to an ATU.
The fresh air requirement is to be trunked to the ATU and the requirements of Clause 5.6.a implemented.
b. For combined sleeping and recreation spaces:
(1) Of the total air supplied to the space, 80% is to be supplied direct to the sleeping area and 20% direct to the recreation area;
(2) The total recirculation is to be taken from the recreation area only, so that all the air supplied to the sleeping area will pass through the recreation area;
(3) A controllable air flow of between 0.005m3/s and 0.01m3/s is to be provided to each bunk, the total quantity supplied to bunks being at least 50% of the total air flow delivered to the sleeping area. The remaining air supplied to the sleeping area is to be evenly distributed throughout the compartment.
c. For cabins and sleeping areas:
(1) Where more than one bunk is fitted an individual, controllable, air flow of 0.005m3/s and 0.01m3/s is to be provided to each sleeping position, the remainder of the air being distributed evenly throughout the compartment;
(2) In single berth cabins an even distribution of cooled air is to be provided by linear grilles or diffusers.
5.8 Medical Spaces
5.8.1 Sick Bays
a. Sick bay complexes are to be airconditioned by dedicated ATU with fully trunked distribution, fresh air, recirculation and where necessary, exhaust systems. The Medical Complex is to maintain a positive pressure in relation to adjacent compartments surrounding the complex in order to prevent the ingress of any possibly contaminated air thereby ensuring sterility. Similarly the Operating Theatre is to have a relative positive pressure in relation to the adjacent Medical Compartments. Fresh air make up is to be via a NBC AFU with bypass arrangements. Sick bays are to be served by one of two system configurations, the particular one being chosen by the size, type and number of compartments involved.
b. Temperatures within the Complex are to be maintained as follows:
(1) Heating 22°C DB minimum ± 1°C;
(2) Cooling 23.5°C Effective Temperature (27°C DB/19.6°C WB/RH 50%).
c. The ambient temperature in some compartments, typically the Operating Theatre, Treatment Room/Dispensary and Surgery is to be capable of being quickly adjusted by the surgeon as dictated by the patient's condition.
Designated compartments and temperature ranges required are to be specified at the outset of the design.
d. Where a complex includes dedicated WC, showers, bathrooms, etc., the total air flow through and the positioning of terminals within these spaces is to be such that toxic and noxious odours are speedily cleared without migration to other compartments and condensation is minimised.
e. In Operating Theatres high level and low level exhausts are to be provided, low level exhausts are to be sited as close to the operating table as possible. Supply terminals, with a minimum outlet velocity of 3 m/s, are to be arranged on both sides of the operating table to give a uniform overall distribution.
f. In combined Sick Bays and at Emergency Operating Stations (EOS), under normal conditions, air is to be distributed evenly throughout the space but it is possible to reconfigure the distribution system so that when the operating table is in use an arrangement similar to that installed in Operating Theatres is available. The two possible system configurations indicated in Clause 5.8.1.a are as follows.
5.9 Configuration No 1 (Full fresh air cooling)
a. This type of system is to be used for small complexes or for sterile compartments in larger complexes where it is possible to ventilate all compartments using airconditioning and exhaust systems without incurring a significant increase in either the numbers of AFU required or the total connected cooling load.
(1) The total air flow required is to be trunked direct from the AFU fan outlet to the inlet of the dedicated ATU.
(2) The ATU is to be capable of cooling or heating the air to the standard specified and distributing it as required throughout the medical compartments. All the air is then to be discharged directly overboard, via the potentially contaminated or noxious spaces within the complex, by a trunked mechanical exhaust system.
(3) The exhaust system is to be balanced such that the requirement at Para 5.8.1a is maintained.
(4) This configuration requires all the air delivered to the complex, or sterile compartments as indicated above, to be treated as a known leakage when assessing AFU capacities and numbers.
(5) The total air flow to the complex is to be comprised of a quantity of fresh air to:
(a) Keep CO2 content below the permitted maximum levels with all compartments fully manned and occupied;
or
(b) Equal the amount of air required to be exhausted from designated compartments (a minimum 15air changes per hour).
Whichever is the greatest, plus any additional air required for airconditioning purposes.
5.10 Configuration No 2 (Semi-recirculation)
a. This system is to be adopted when full fresh air cooling is impractical due to its impact on the total connected cooling load and/or on the number of AFU required in the fire zone that contains the medical complex. It combines one dedicated ATU configured as outlined above to serve designated sterile compartments and a fully trunked airconditioning system with a mechanical exhaust as follows:
(1) Compartments within the complex would normally be classified at the outset of the design as either:
(a) Undesirable to recirculate air from, e.g. sterile compartments, WC's, sluices, etc.;
or
(b) Unlikely to contain pollutants, e.g. Consulting Room, office, dispensary, etc.;
Compartments in (a) above would form the full fresh air unit and compartments in (b) would form the part fresh air/recirculation unit;
(2) Dependant on the method used for the calculation of the fresh air quantities required for the vessel, the total air flow via the mixed fresh air/recirculation ATU is to be comprised of a quantity of fresh air to:
(a) keep CO2 content below the permitted maximum levels with all compartments fully manned and occupied;
or
(b) Equal the amount of air required to be exhausted from designated compartments (a minimum 15air changes per hour);
Whichever is the greatest, plus any additional air required for airconditioning purposes;
(3) The total fresh air and the air recirculated from Class B compartments is to be fully trunked to the ATU inlet, heated or cooled as required and distributed throughout the complex;
(4) All the air from compartments classified as `undesirable to recirculate from' is to be discharged directly overboard by a mechanical exhaust system such that the requirements of Clause 5.8.1.aare met;
(5) The total air handled by the exhaust system is to be treated as a known leakage when assessing AFU numbers.
5.10.1 Dental Surgery
a. This space is to be airconditioned and may be included as part of the medical complex or any other adjacent system. A supply, diffuser type terminal is to be positioned to give maximum air movement at the dental chair.
5.11 Bathrooms and WC
5.11.1 General Requirements
a. All systems serving these spaces, whether airconditioned supply, fresh air supply, mechanical exhaust or recirculation, are to be fully trunked and the ATU (or CW unit coolers, see Section 6) are to be dedicated to these spaces.
b. Where practicable and economic, bathrooms, WC and urinals, within a fire zone should be grouped together and served by the same system.
c. Where practicable and economic each space is to be served by dedicated odour filters to ensure that all noxious and undesirable odours are removed from the recirculating air before it is redistributed and cross contamination does not occur between compartments on a group system. The siting of odour filters is to ensure that the moisture content of the air passing through them is as low as possible.
d. A negative pressure relative to surrounding compartments is to be maintained within these spaces by arranging a balanced supply and exhaust/recirculation airflow but ensuring that a greater negative pressure is available at the exhaust/recirculation terminals relative to the supply terminals positive pressure.
5.11.2 WC and Urinals
a. The distribution systems for WC and urinals are to be designed to achieve two prime objectives, viz:
(1) Maintaining of temperatures, relative humidities and oxygen levels to airconditioning standards under `open ship' and `closed down' conditions in all types of climates. In `closed down' conditions, the period is to be indefinite unless the STR for the vessel states otherwise;
(2) The removal of all noxious and undesirable odours from these spaces without any other compartment or space being polluted.
b. To achieve these objectives the total air flow through any WC and/or urinal space is to be sufficient to:
(1) Ensure 15 complete air changes per hour within the compartment;
or
(2) Satisfy the minimum air requirements for WC cubicles, urinals and washbasins contained within the space when these spaces are mechanically ventilated and not air conditioned;
or
(3) Maintain airconditioning standards in all climatic conditions.
Whichever is the greatest.
c. The type of systems used for WC and urinals are to be tailored to the circumstances within individual compartments and, to obtain the most effective and economic performance, system designs may vary throughout the ship.
d. Within the compartments a minimum of 0.035 m3/s of air is to be taken from each WC cubical and urinal and 0.02 m3/s is to be taken from each washbasin (See Clause 5.11.2.b(2) above).
e. In WC cubicles the supply terminal is to provide approximately 0.015 m3/s and is to be so positioned to enable a downward jet of air to be delivered inside the door. The exhaust/recirculation terminal is to be positioned at the rear of the cubicle at deckhead level.
f. Recirculation/exhaust terminals are to be positioned directly above urinals, at deckhead level.
g. The supply air, other than that required for WC cubicles, is to be evenly distributed throughout the compartment, care being taken to ensure that no short circuiting takes place between supply and exhaust/recirculation terminals.
h. Individual WC that are remotely sited can be exhausted directly overboard by combining them with the mechanical exhaust systems from hazardous spaces, providing that a dedicated exhaust fan has not been specified. The supply to these compartments can be taken from an adjacent airconditioning system or direct from the citadel via a bulkhead opening. In such cases an odour filter is not required and the exhaust is to be treated as a known leakage when assessing AFU requirements.
5.11.3 Bathrooms
a. Air distribution systems for bathrooms are to be designed to achieve two prime objectives, viz:
(1) Maintaining of temperatures, relative humidities and oxygen content to airconditioning standards under `open ship' or `closed down' conditions, in all climatic conditions and at all compartment operating levels. In the
`closed down' state, the period will be indefinite unless specified otherwise in the STR for the vessel;
(2) The prevention of excessive condensation occurring on ship's structure at any level of manning or operation within the compartment and in any climatic condition.
b. To achieve these objectives the total air flow through any bathroom is to be sufficient to:
(1) Ensure 15 complete air changes per hour within the compartment;
or
(2) Satisfy the minimum air requirements for each bath, shower and washbasin, when the space is mechanically ventilated and not air conditioned;
or
(3) Maintain airconditioning standards in all climatic and compartment conditions;
Whichever is the greatest.
c. The systems are to be tailored to individual bathrooms and their design may vary throughout the ship, the main priority being the attainment of the objectives in the most effective and economic manner.
d. A minimum air flow of 0.035 m3/s is to be recirculated from each shower and bath space and 0.02 m3/s from each washbasin (See Clause 5.11.3.b.(2) above).
e. The supply is to be distributed throughout the compartment with a concentration at the drying positions.
f. Heaters serving bathrooms are to be sized to provide a temperature of 22°C at drying/undressing positions in cold weather conditions.
g. Bathroom usage is cyclic, and to counter overcooling during periods of minimum manning and operation in temperate climates, the diversion of CW by thermostatic control valves or the use of reheaters is to be considered.
h. Where practicable and cost effective, to limit condensation, dehumidifiers may be installed to augment the removal of moisture from the air during periods of high manning in warm climates. These units are to be manufactured to `good commercial marine standards' and engineered to cope with all expected ship motions and attitudes.
i. Private bathrooms are to be included with the relevant compartments and airconditioned as a group, the recirculation being trunked back to the ATU and an odour filter fitted in the branch from the bathroom/WC. Alternatively where the fresh air bleedoff from the grouped compartments is equal to or greater than the total air flow required in the bathroom sufficient air may be exhausted via the bathroom and discharged directly overboard by a convenient mechanical exhaust ventilation system.
5.12 Galleys and Associated Spaces
5.12.1 Galley, Servery and Scullery
a. These spaces, treated as a group, are to be airconditioned or partially airconditioned with selected equipment being mechanically exhausted. The airconditioning is to be by a dedicated ATU with a fully trunked distribution, recirculation and fresh air system. These spaces are to be capable of operating in the `closed down' state indefinitely or to the period specified in the STR of the vessel.
b. Odour filters are to be fitted to ensure that all odours are removed from the recirculating air before it is redistributed throughout the compartments. The siting of these filters is to ensure that the moisture content of the air passing through them is as low as possible.
c. A negative pressure, relative to the surrounding compartments, is to be maintained within these spaces by arranging a balanced supply and exhaust airflow but ensuring that a greater negative pressure is available at the exhaust/recirculation terminals relative to the supply terminals positive pressure.
d. All trunking within the galley and throughout the respective systems is to be constructed of mild steel with welded seams and flanges and galvanized after manufacture, except where it forms part of a canopy when it is to be of stainless steel.
e. Stainless steel canopies are to be fitted over all equipments that are potential sources of fumes and/or steam.
f. All canopies are to be fitted with condensate drains leading to the nearest deck drain, saveall or sink and those fitted over ranges, frying and grilling equipments are to be provided with grease filters with portable drip trays.
g. Exhaust trunks serving ranges, frying and grilling equipment are to be fitted with fire flaps as detailed in Section 9. The air exhausted from these positions is to be a minimum of 30% of the total airconditioning supply and is to be discharged directly overboard.
h. Within the galley, supply air terminals are to be so positioned in relation to exhaust/recirculation terminals (See Clause 5.12.1jbelow) to prevent the escape of odours and steam into the compartment.
i. The supply air is to be evenly distributed throughout the compartments, care being taken, when positioning terminals, to ensure that cooled air is not directed on hot food at serving counters nor onto the heads of galley personnel.
j. Exhaust/recirculation terminals are to be positioned within the canopies and over other sources of heat, steam and odours, e.g. refrigerators, sinks, preparation areas, etc.
k. To prevent over cooling when galley equipment is not in use and in cold climates the heat extraction is to be regulated in accordance with Paras 5.6.aand 5.6.b, i.e. by:
(1) Controlling the flow of CW through the cooling coils by means of a thermostatic, threeway, diverter valve;
(2) Reducing the air flow passing over the cooling coils by means of variable volume fans;
(3) A combination of (1) and (2).
l. Acoustic insulation is not as a rule to be fitted in galley exhaust or recirculation trunking, however should the achievement of noise target levels be impractical then it may be fitted if lined internally with a material suitable to facilitate steam lance cleaning.
5.12.2 Pantries and Pantry/Serveries
a. These spaces are to be airconditioned and treated similarly to galleys and sculleries. Wherever practicable they are to be grouped with a galley, servery and scullery and served by a single system.
b. Where a pantry is sited remote from a galley it is to be supplied from an adjacent airconditioning system, the exhaust being discharged directly overboard, via a compatible mechanical exhaust system, or returned to the ATU via a fully trunked recirculation system.
c. Odour filters, grease filters, and fire flaps are to be fitted as appropriate.
5.12.3 Miscellaneous
a. Continuous flow steam emitting water heaters and boiling urns sited in dining halls, etc., are to be provided with canopies and drains and ducted to the most convenient exhaust or trunked recirculation system.