6. LAYOUTS AND CONSTRUCTION WORK


6.1 Typical Layouts

6.1.1 General
6.1.2 Shrimp processing
6.1.3 Whole fish processing

6.2 Building

6.2.1 General
6.2.2 Walls
6.2.3 Floors
6.2..4 Ceilings
6.2.5 Doors and Windows
6.2.6 Lighting
6.2.7 Ventilation
6.2.8 Drains
6.2.9 Power supply
6.2.10 Water supply
6.2.11 Factory yards

6.3 Site

6.3.1 Location
6.3.2 Site level
6.3.3 Communications
6.3.4 Site size


6.1 Typical Layouts

6.1.1 General

It is unlikely that in any situation there is only one ideal layout for the processing area, but at the planning stage an attempt should be made to conform with some fundamental requirements. Two main considerations are hygiene and economy, and since there is seldom scope for a compromise on hygiene, this aspect should always be given priority. Other requirements are often in conflict, therefore, a compromise has to be made depending on the importance of the different elements in the local situation.

Factory layout depends on the building available and particularly on its size and shape. It is therefore more likely that a good layout will be achieved with a new building than by converting an old one, and this consideration may influence the decision on the choice of building and site.

Some of the factors to be considered, when planning factory layout, are listed below but others, which may depend on local conditions, may be equally important, particularly those relating to building regulations and other relevant legislations.

6.1.2 Shrimp processing

Depending on the size of shrimp and the availability and cost of labour. shrimp may be processed by mainly mechanical or manual methods.

A suggested factory layout for processing 800 kg/h of small-to-medium size shrimp using a machine peeling operation is shown in Figure 67. Prior to planning a factory layout, a flow chart should be prepared and the diagram relating to this operation is shown in Figure 68.

Larger shrimps are more likely to be suitable for processing with a mainly manual operation, and a typical layout together with the corresponding flow chart are shown in Figures 69 and 70.

6.1.3 Whole fish processing

In this case, a more elaborate flow chart -Figure 71- has been prepared showing the different operations and the movement of produce and materials such as packaging and ice. The term "whole fish" can cover a wide variety of species and products which may require different prefreezing and post-freezing treatments. therefore, the layout in Figure 72 only represents a typical case incorporating many of the elements associated with good practice.

6.2 Building

6.2.1 General

If new premises are to be constructed. or major alterations have to be made to an existing building. much of the detail in design and layout will be governed by local building regulations and the special requirements of the user will therefore have to be incorporated within these restraints.

Higher standards of hygiene, improved handling, more economical use of space and lower costs for heating or air conditioning can be achieved if all operations are confined to one building.

Fish handling should preferably be confined to the ground floor only since this will make good drainage easier and cheaper, structural costs will be reduced and the main working area will be more accessible to vehicles and thus ensure quick handling and avoid delays.

6.2.2 Walls

Walls should be smooth and waterproof.

Brickwork or blockwork of dense concrete blocks are preferable for the main walls since they provide a good base for a smooth washable finish; exposed steelwork must be protected against corrosion and may also need a coating that prevents condensation. Steel reinforcement should be covered with at least
40 mm of concrete.

One satisfactory wall finish is obtained with ceramic tiles. These are expensive. and if tiling to the full height of the wall is out of the question, then fit tiles to a height of 1-11/2 m and have a cement rendered finish above. The top edge of the tiles should be finished with a rounded tile, or the tiling made flush with the wall surface above.

Table 72 Factory details for shrimp processing and freezing

Process and capacity

Total factory area (m)

Factory subdivisions

Temperature
(C)

Category

Area (m)

Machine peeling and freezing shrimp 800 kg/h

600

Miscellaneous processing

494

+15

Chilling

42

+1

Cold storage

64

-30

Office accommodation and associated facilities    
Plant room/workshops    
Hand peeling and freezing shrimp 250 kg/h

432

Miscellaneous processing

390

+15

Chilling

22

+1

Cold storage

20

-30

Office accommodation and associated facilities    
Plant room/workshops    

Table 73 Factory details for whole fish freezing processing

Process and capacity

Total factory area (m)

Factory subdivisions

Temperature
(C)

Category

Area (m)

Blast freezing whole fish
250 kg/h

640

Miscellaneous processing

378

+15

Chilling

16

+1

Cold storage

143

-30

Office accommodation and associated facilities

59

+17

Plant room/workshops

44

+15

The walls should be kept free of unnecessary projections; pipework should be sunk flush with the wall surface or neatly boxed in.

Jutting corners susceptible to damage from passing traffic should be protected by a steel plate, especially where the wall is finished with tiles. Corners between walls should be rounded off.

Whatever the decorative finish, a cement-based rendering on the brickwork or concrete block wall is desirable to give a smooth, easily cleaned surface that can be hosed down. Cement paints and chlorinated rubber paints stand up well to wet conditions; wherever higher resistance to water and brine is needed, epoxy, urethane and neoprene paints should be considered and the manufacturers recommendations complied with. Distempers are not very suitable. Always use light colours.

Figure 67 Proposed layout and flow plan for 800 kg/h medium and small shrimp processing plant

Figure 68 Flow chart for processing medium and small shrimp

scale ~ 1 : 100

Figure 69 Proposed layout and flow plan for 2 t/day hand-peeling shrimp processing plant

Figure 70 Flow chart for processing large shrimp

Figure 71 Flow chart for whole fish freezing

Figure 72 Proposed layout for whole fish freezing

6.2.3 Floors

Floors should be hard-wearing, non-porous, washable, well drained, non-slip and resistant to possible attack from brine, weak ammonia, fish oils and offal.

Concrete is attacked by fish oils and also by the continued action of strong brine; it is also attacked by acids but not by ammonia. The rate of attack depends on the density of the concrete and on the amount of wear that removes the attacked material to expose fresh material; thus, when concrete is used as a floor finish, it must be of high quality. If the surface is subject to very heavy wear, by iron-wheeled bogies for example, then concrete is not very suitable.

Clay tiles or paviors make the most hard-wearing floors for fish-working spaces. They should be about 50 mm thick and laid flush in jointing made from furane or cashew-nut cement. Latex cement may be substituted as a cheaper jointing material, but is not quite so satisfactory.

Avoid severe damage to floor surfaces by reducing necessary dragging of equipment and dropping of boxes; fit your trunks and trolleys with synthetic rubber-tyred wheels instead of steel ones.

Surface dust is sometimes a nuisance on an otherwise good quality concrete floor; treatment with sodium silicate solution or with magnesium or zinc silco-fluoroide solutions is often effective.

When traffic is not too heavy, and a more decorative surface than concrete is required, terazzo tiles can be fitted.

Sheet finishes, such as rubber or PVC that have to be stuck down, are usually not suitable for fish-working floors. Rubber is attacked by fish oils, and PVC swells when wetted.

Asphalt flooring is not resistant to oils and fats, and is rather soft; it is, however, not slippery when wet, is fairly hard-wearing and waterproof. It is suitable for premises handling white fish where traffic is not severe.

An alternative to the installation of an expensive flooring material throughout is to fit very hard-wearing tiles at the points of greatest wear and to fill in the remainder of the area with granolithic concrete.

Make new floors sturdier than the present traffic demands if there is any likelihood of heavier equipment, such as fork-lift trucks, being introduced later.

Loading bays that are subject to extra heavy traffic may require the use of special metal tiles with an infilling of concrete; the anchor plate type is suitable. As far as possible, loading bays that are continually open should be completely screened from the working area of the factory.

The hard, smooth finishes that are most easily cleaned and best withstand hard wear are usually slippery; it is often necessary to compromise. A certain amount of ribbing in the floor surface may be necessary, but the best safeguard is regular washing and scrubbing of the floor. If ribbed tiles are used, the grooves should run down the drain slope. Some clay tiles are supplied with a specially roughened non-slip surface, and carborundum can be incorporated on granolithic finishes. Avoid sudden changes from one floor surface to another that has a different degree of slipperiness; the danger of staff slipping is greatest where two such surfaces adjoin.

Fish working floors are continually being wetted, hence adequate drainage is essential. A slope of 1 in 100 is usually enough, and the slope should be so arranged that the regular traffic of men and vehicles is across it, not up and down; there is then less danger of accidents. Slopes greater than 2.5 in 100 are dangerous, therefore, the slope of the floor should be between the foregoing limits.

Take care to avoid any area of floor surface on which stagnant pools of liquid can lie; surface attack can be greatly accelerated under these conditions.

All junctions between floor and walls should be covered and made watertight, thus eliminating corners that cannot easily be cleaned. Where possible, the floor material should be carried up the wall for a short distance.

All floors should be vermin and insect-proof; joints around pipes and fitments that pass through the floor should be filled with impervious material, such as hard cement or pitch mastic.

If a floor other than the ground floor of a building has to be used for wet fish processing, such a suspended floor needs a waterproof membrane or underlay between the structural floor and the finish of tiles or concrete; suitable materials for such a layer include acid-resistant asphalt and bituminous felt. Expert advice should be sought to ensure that such a floor is laid in a proper manner to protect the structure below.

6.2.4 Ceilings

Ideally, the ceiling should be a continuous, smooth, unbroken surface that can be easily cleaned, for example, the underside of a concrete slab. If, however, there is a roof space containing beams, trusses, service piping or machinery, then a suspended ceiling is desirable unless the building is very high.

Ceiling boards should be unaffected by moisture; asbestos-based boards are unsuitable.

Condensation may be troublesome in cold weather because of the high humidity within the building; insulation should be provided above the suspended ceiling and the roof space well ventilated to the open air. Some forced warm-air ventilation may be needed in extreme cases and expert advice should then be sought.

Insulated ceilings can be finished with a hard gloss paint in a light colour.

A suspended ceiling that is not insulated should be constructed of an absorbent material, such as plaster, and finished with a soft non-washable distemper; absorbent colour washes of this kind should be washed off and renewed once every six months.

Where the roof beams or trusses are exposed, that is where no suspended ceiling is fitted, paints for the steelwork should be chosen carefully to avoid the risk of flakes falling into the factory. Aluminium structures cost more but can be left unpainted.

The clear internal height must suit the factory production and storage, and its adequacy for all future requirements should be considered.

The plant must be accommodated with sufficient clearance for its installation, removal and maintenance, while mobile equipment, such as fork trucks, may call for special headroom for efficient working. Any tendency for a given type of production machinery to increase in height should also be considered when deciding on the clear height for the framework of a factory building.

Ancillary equipment nowadays is commonly slung from the roof structure; this may increase the height requirement.

Storage space afforded by an increase in the vertical direction will probably prove cheaper to provide than the equivalent obtained by increased floor area.

6.2.5 Doors and windows

Doors and window frames should be of non-porous, non-absorbent materials; wood is not very suitable.

Doors should be made without inset panels or ledges; a flush surface is much more easily kept clean. Doors should be self-closing and the bottoms protected by kicking plates.

Window frames of a suitable aluminium alloy need no painting, but regular washing is needed to keep the metal bright and to prevent pitting corrosion. Steel windows must be heavily galvanized and kept well painted, both to protect the metal against corrosion and to reduce the risk of paint flaking.

Wooden doors and window frames should be kept well painted.

Fly proof screens of 8-mesh British Standard wire gauze should be fitted to doors and windows during the summer months; fly proof doors should be self-closing.

6.2.6 Lighting

Good plant lighting will allow workers to do their jobs properly without strain, and expose dirt and other sources of contamination.

Maximum use should be made of natural daylight by providing adequate windows and skylights.

Good diffused general lighting to augment or replace daylight is best achieved with fluorescent lights.

A light level of 500-750 lux is usually sufficient, depending on the difficulty of the visual tasks done in the factory.

Coloured lights decrease rather than increase a person's liability to detect colour differences in foodstuffs.

General lighting should be augmented, where necessary. by individual lights at weighing and inspection points for example.

Light shades and fittings should be of simple design and easily cleaned.

6.2.7 Ventilation

The atmosphere in fish plants is humid; good ventilation will reduce the nuisance of condensation. remove bacteria-loaded moist air. dust and smells.

Good temperature control can provide comfortable working conditions without allowing air temperature to rise too high and so rapidly spoil the product.

Windows and skylights can be used for ventilation. but judicious use of exhaust fans or special roof vents is preferable.

Ventilation ducts should be fitted within walls or ceilings. or held well clear on bearers to allow for easy cleaning. The inlets should be insect-proof and away from dusty places. All metal fitments that are likely to rust should be well protected by paint. Screens should be removable for cleaning.

A mechanical air conditioning system can be installed to control temperature and humidity, in which case a competent heating and ventilating engineer should be consulted.

6.2.8 Drains

Floor drainage channels should have easily removable gratings and should be wide enough to permit brushing out.

Main drains should not connect directly to a sewer without an intermediate trap. and should be large enough to carry away all waste water without choking or flooding. Traps should be readily accessible for cleaning and have properly fitting inspection covers bedded in grease.

6.2.9 Power supply

Make provision not only for present but for likely future requirements of electricity when wiring the building; install wiring of ample capacity in proper conduit, and fit plenty of power points in convenient places. All power points should be properly earthed and made waterproof wherever necessary they should comply with existing electrical regulations.

6.2.10 Water supply

A generous supply of water must be available at numerous points throughout the premises, both for use during processing and for cleaning. Storage tanks should be kept covered.

Staff should not wash in sinks and tubs that are used for processing; hand-wash basins should be located where they will be regularly used by fish workers, preferably in the fish-working space itself, in addition to, or instead of, those adjacent to lavatories.

6.2.11 Factory yards

The whole yard should have an even, impervious surface and be properly drained. If returnable fish boxes are stored and washed there. the walls adjacent to that part of the yard should be cement rendered to a height of at least 1.5 m. Adequate clean. dry storage should be available for box storage, preferably under cover; new boxes and other packaging materials should be stored inside the building.

All offal bins. which should have close-fitting, deep-lidded lids and should preferably be stored in close out-buildings. should not be left exposed in the open yard. If they must be stored in the open, they should be kept in a cool, shady place, either on a smooth concrete plinth, or supported at least one foot clear off the ground on a metal stand so that the paving beneath can be cleaned. The whole stance should be protected by screening walls, and be properly drained.

6.3 Site

6.3.1 Location

The following list is not comprehensive, but it gives guidance on some of the factors that may have to be taken into account when selecting a site for a freezing and cold storage complex:

The cost of land
The location of the site with respect to raw material supplies
The continued availability of raw material supplies
The location of the site with respect to markets and other outlets
Are there likely to be local objections to the complex
Will local conditions add to the building costs
Local rates and taxes
Local grants or other aids available
The cost of site preparation
Availability of sufficient water of the right quality
Adequate power supplies
Are there nearby ancillary support services such as ice plants
The cost of disposal of liquid and solid waste
Is there land and other services available for future expansion

6.3.2 Site level

A flat, level site is preferable since this is likely to result in lower site preparation costs.

However, the cold-store floor level may be raised to provide a suitable loading bank of about 1.4-1.5 m high for vehicles. On sites where there is likely to be problems with ground flooding, it is essential that the cold store in particular is kept above the maximum level likely. Elevating the cold store above ground level also allows natural air ventilation to be used to prevent "frost heave".

For some of the reasons given above, other floor levels in the complex may also be elevated above ground level, but on some sites a two-level system may be contemplated since some of the needs of the processing area are best served by a ground-level floor.

6.3.3 Communications

The availability of suitable communications is often the major consideration when choosing a site both for the movement of goods and for other services such as labour.

Ideally, the site should be close to the source of raw materials, which means that it should be near the point of off-loading from fishing vessels. However, a major portion of raw material supplies may be consigned from more distant ports and it may therefore be advantageous to site the complex on the periphery of an urban area to ensure easy vehicle access.

If goods have to be loaded on and off a vehicle for delivery to the complex, it is usually of relative unimportance whether the journey is very short or say s km, since the time spent on loading and unloading accounts for most of the costs.

It is also often more important to have good communications rather than short journeys, since this will govern the size of loads to be carried and also transport times.

When journeys are long it may also be necessary to contemplate the cost of breakdowns in communications or the cost of ensuring that there are adequate contingencies to cope with these situations.

6.3.4 Site size

Adequate space for vehicle access and manoeuvring is of prime importance, and an area outside the main buildings may also be required for the storage of pallet frames. Vehicle size and the type of operation will be decisive when planning the layout and size of the site, as also will the need for future expansion. Modular store construction allows cold store expansion to be achieved by adding on to existing stores, and the site arrangement should allow this to be achieved with similar standard-sized units.

Parking space for other vehicles and equipment should also be adequate since if no allowance is made they often interfere with the cold storage and factory traffic.