1、BRITISH STANDARD BS5502-74: 1991 Buildings and structures for agriculture Part74: Code of practice for design and construction of bins and silos for combinable cropsBS5502-74:1991 This British Standard, having been prepared under the directionof the Technical Sector Board for Building and Civil Engi
2、neering (B/-), was publishedunder the authority ofthe Standards Board and comesinto effect on 20December1991 BSI 03-1999 The following BSI references relate to the work on this standard: Committee reference B/549 Draft for comment90/14591 DC ISBN 0 580 20257 7 Committees responsible for this British
3、 Standard The preparation of this British Standard was undertaken by Technical Committee B/549, upon which the following bodies were represented: British Cement Association British Commercial Glasshouse Manufacturers Association British Precast Concrete Federation Ltd. British Veterinary Association
4、 Department of Agriculture Northern Ireland Farm and Rural Buildings Centre Farm Buildings Association Health and Safety Executive Institution of Civil Engineers Ministry of Agriculture, Fisheries and Food National Farmers Union Royal Institute of British Architects Royal Institution of Chartered Su
5、rveyors Scottish Office (Agriculture and Fisheries Department) Steel Construction Institute Transport and General Workers Union Water Services Association of England and Wales Amendments issued since publication Amd. No. Date CommentsBS5502-74:1991 BSI 03-1999 i Contents Page Committees responsible
6、Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 General 1 4 Design, materials and construction 1 5 Environment 4 6 Services 6 7 Fire precautions, safety, welfare and hygiene 7 8 Safety signs and notices 7 Index 8 Table 1 Bulk densities (for determining volumes) 3 Table 2 Angle of repose f
7、or crops 3 Table 3 Slopes for crop flow 3 Table 4 Recommended storage period for grain at or below16C and at various moisture contents 4 Table 5 Equilbrium moisture content and relative humidity for wheat and barley 4 Table 6 Maximum drying temperature for grain 4 Table 7 Maximum air temperature for
8、90% germination of grass seeds 5 Table 8 Maximum storage of wheat with respect to germination 5 Table 9 Ventilation rates 5 Table 10 Air velocity 5 Table 11 Maximum air speeds 5 Table 12 Resistance to airflow (in Pascals) per metre depth of crop 6 Table 13 Temperature for chilled storage of grain 6
9、Publication(s) referred to Inside back coverBS5502-74:1991 ii BSI 03-1999 Foreword This Part of BS5502 has been prepared under the direction of the Technical Sector Board for Building and Civil Engineering. It comprises a new Part to BS5502. While BS5502 is being revised and added to, the opportunit
10、y is being taken to restructure the standard into the following broad subject areas: Part0: Introduction and consolidated index; Parts10 to19: Reference information and legislation; Parts20 to39: General design; Parts40 to59: Livestock buildings; Parts60 to79: Crop buildings; Parts80 to99: Ancillary
11、 buildings. More specifically, the crop building series will comprise: Part 60: Code of practice for design and construction of buildings for mushrooms; Part 65: Code of practice for design and construction of crop processing buildings; Part 66: Code of practice for design and construction of chitti
12、ng houses; Part 70: Code of practice for design and construction of ventilated on floor stores for combinable crops; Part 71: Code of practice for design and construction of ventilated stores for potatoes and onions; Part 72: Code of practice for design and construction of cool stores; Part 74: Code
13、 of practice for design and construction of bins and silos for combinable crops. A more detailed description of the new structure of BS5502 is given in Part0. The object of introducing the new structure is to allow subject areas to be broadly characterized, and related subject matter, whether in the
14、 form of recommendations, guidance or supporting data, to be rationalized and brought together. It will also allow sufficient flexibility to enable BS5502 to be expanded and developed in a logical way in the future. It has been assumed in the drafting of this Part of BS5502 that the execution of its
15、 provisions is entrusted to appropriately qualified and experienced people, for whose guidance it has been prepared. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a
16、British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1to8, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments
17、 incorporated. This will be indicated in the amendment table on theinside front cover.BS5502-74:1991 BSI 03-1999 1 1 Scope This Part of BS5502 gives recommendations for the design and construction of bin and silo systems for storing combinable crops. NOTE 1For on floor storage see BS5502-70. NOTE 2T
18、he titles of the publications referred to in this standard are listed on the inside back cover. 2 Definitions For the purposes of this standard, the definitions given in BS6100 apply. 3 General 3.1 Storage The function of crop storage structures is maintenance of crop quality by control and retardat
19、ion of the natural biological processes of the crop. The quality is maintained by controlling storage temperatures and relative humidity. Drying usually precedes storage by the application of heat from a continuous flow or batch bin drier. Alternatively, drying can take place within the bin/silo its
20、elf. 3.2 Siting Consideration should be given to the siting of crop stores (see BS5502-20). In particular, consideration should be given to the following: a) choosing a level site where there is no risk of flooding; b) choosing ground with adequate bearing capacity; c) ease of access for large trans
21、port; d) availability of services; e) nuisance arising from transport, machinery noise and the creation of dust; f) allowing for future expansion. 3.3 Type of storage 3.3.1 The design of bins and silos will be determined by the following factors: a) type of produce stored; b) storage duration; c) dr
22、ying system employed; d) sophistication of the mechanical handling; 3.3.2 Crops may be either: a) pre-dried and stored in a bin with sufficient ventilation to keep the crop conditioned; b) dried in a bin linked to a drying fan. 3.3.3 Bins/silos can be round or square with flat or hopper bottoms. Pos
23、itioning may be in a semi-circle or in a single or double line format. The storage may be located in the open or under a roof. In either case, the units should be linked to a pit with an elevator and conveyor system. Bins can be positioned in existing buildings. 4 Design, materials and construction
24、4.1 General 4.1.1 The design, choice of materials and construction of bins/silos for crops should be in accordance with BS5502-20, BS5502-21, BS5502-22, BS5502-23 and BS5502-25. 4.1.2 Foundations and support structures for bin and silo stores should be designed and constructed to withstand loads fro
25、m the stored crops and equipment. 4.1.3 Structures should be designed to minimize differential settlement, deflection and structural movement that could cause fracturing of surfaces and permit moisture ingress or infestation, so putting the stored products at risk. 4.1.4 Store interiors require clea
26、ning or fumigation after the storage period and this should be considered in the choice of materials. 4.1.5 Materials and treatments used in the construction should not impart odour or taint to the crop. 4.1.6 All parts of the structure should be constructed in accordance with the recommendations gi
27、ven in BS8000. 4.2 Floors Floors should be level with an even surface. Floors should be designed and constructed to withstand the load from the crops, plant and equipment. The surface should be hard wearing, capable of being cleaned and not susceptible to cracking or crazing. To prevent moisture ing
28、ress to the crop, a damp-proof membrane should be provided. Thermal and shrinkage movement should be minimized by the correct placing of construction, expansion and contraction joints. 4.3 Walls The material for bin/silo construction will vary according to the location. Bins to be used externally sh
29、ould be weatherproof and be covered. Where bins/silos are positioned inside a building, weatherproofing is not required and bins do not require a top.BS5502-74:1991 2 BSI 03-1999 4.4 Roof and wall cladding Bins/silos may support their own roof/cover or the roof/cover may be independent; in either ca
30、se the roof/cover should be fixed so as to prevent entry of rain and driven snow. Louvred outlets should be provided at high level for ventilation. Consideration should be given to the exclusion of natural light in order to discourage birds and to the screening of ventilators to keep out birds and v
31、ermin. 4.5 Doors Where bins/silos are uncovered within a roofed structure, doors should be fitted to the structure to protect equipment from the weather and to prevent infestation. The door dimensions and position should be determined by the layout and use of the store. An opening of4.5m4.5m should
32、normally be used, but larger access may be required. Personnel doors and emergency escape doors should be included. Provision should be made for securing side-hung doors when open to prevent damage by high winds. The door threshold should be designed to keep out water. The external access area shoul
33、d slope away from the doorway. 4.6 Reception pits 4.6.1 Reception pits should be self-emptying and should be designed to hold the required tonnage of crop relative to the throughput of the system. Where ground conditions restrict the size, a powered intake should be considered. Sloping surfaces shou
34、ld be not less than45 from the horizontal. Pits should incorporate a damp-proof membrane or, where the water table is likely to rise above base level, they should be constructed either using concrete which is fully waterproof or with a fully anchored waterproof lining. The top of the pit should be f
35、itted with a grille to act as a safety guard which should be designed to support the discharging machinery, if required. 4.6.2 Pits not designed to support vehicles should have a300mm high kerb along the edge that would be approached by vehicles. 4.7 Elevator pits Elevator pits should be constructed
36、 large enough to provide access to elevators for maintenance, repair and replacement. Pits should incorporate a damp-proof membrane or, where the water table is likely to rise above base level, they should be constructed either using concrete which is fully waterproof or with a fully anchored waterp
37、roof lining. A fixed ladder and lighting should be provided. The pit cover should permit access and should be designed to carry at least the minimum floor loading (see BS5502-22). 4.8 Grain conveying The delivery rate of the harvesting and handling equipment should be balanced to ensure a compatible
38、 and efficient flow. Discharge conveyors should spread the grain evenly to avoid the formation of compaction and/or separation columns. NOTE 1This rate is determined from the capacity of the combined-harvester/tractor-trailer capacity and the capacity of the intake pit at the store. NOTE 2The capaci
39、ty of elevators and conveyors should be greater than the maximum discharge rate from the drier. Overhead hoppers for filling of lorries should be able to refill between arrivals of lorries. 4.9 Ventilation ducts The floor of a bin should be perforated or should contain lateral ducts within the struc
40、ture to permit the bin to be ventilated. Alternatively, perforated ducts may be positioned above the floor. Care should be taken when sizing the perforations to ensure the free surface area is not blocked by the stored crop. Where oilseed rape is to be dried, the ventilating holes should be not grea
41、ter than1.5mm diameter. NOTE 1Ventilation ducts, if so designed, can be used for air sweep purposes when emptying the bins/silos. NOTE 2Radially ventilated bins are cylindrical with air-permeable walls. Air is introduced via a radial plenum linked to a fan. 4.10 Fan housing Fans for individual isola
42、ted external bin systems can be permanent or transportable and are fixed adjacent to the bin, requiring no housing except for weather protection. For integrated internal nested bins/silos fans may be housed inside the store, but preferably they should be housed in a structure built externally. Louvr
43、ed inlets or top-hung airdoors should be provided to ensure the unrestricted access of air to the fan. The openings should be screened to keep out birds and pests. Nuisance due to noise levels should be prevented by insulation, increasing mass and correct siting. 4.11 Access and walkways Crop storag
44、e installations should include all walkways, stairs and platforms necessary to allow safe access to areas for loading and unloading, for inspection of the crop during storage and for cleaning out and maintenance. Handholds should be provided at the top of all ladders, and ladders should be fixed. Pa
45、rapet rails and kicker boards should be provided to all areas where access is provided.BS5502-74:1991 BSI 03-1999 3 4.12 Store geometry 4.12.1 General dimensions The following factors should be considered when determining the dimensions of bin/silo stores for crops: a) volume of stored crop; b) need
46、 for a uniform ventilation rate throughout the stack; c) space required for loading and unloading; d) space required for equipment; e) management techniques. 4.12.2 Store layout The store layout should allow the efficient flow of the crop through the system from field to store and subsequently from
47、store to sale. There should be access to all parts of the store, where necessary, for maintenance and repair. The level of the reception pit in relation to the ground should be considered. 4.12.3 Bulk density of stored crops When determining storage volumes, bulk densities as given inTable 1 should
48、be used. Under certain conditions these figures can be exceeded. Table 1 Bulk densities (for determining volumes) 4.12.4 Angle of repose Where the crop is to be surcharged, the angle of repose should be taken into account in calculating storage volumes and store geometry (seeTable 2). Table 2 Angle
49、of repose for crops 4.12.5 Slopes for crop flow The steepness of slope down which a crop can flow depends on the surface smoothness of the slope, the nature of the material being handled, its moisture content and cleanliness. Acceptable slopes for most surfaces are given inTable 3. Table 3 Slopes for crop flow 4.12.6 General layouts of freestanding bins and silos Bin sizes range from30t to4500t. Small groups of round bins should be arranged in a semi circle fed by a swinging auger from a central intake pit. Larger ins
