BS 7562-5-1993 Planning design and installation of irrigation schemes - Guide for irrigation equipment《灌溉系统的规划 设计和安装 灌溉设备指南》.pdf

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1、BRITISH STANDARD BS 7562-5: 1993 Planning, design and installation of irrigation schemes Part 5: Guide for irrigation equipmentBS7562-5:1993 This British Standard, having been prepared under the direction of the Agricultural Machinery and Implements Standards Policy Committee, was published under th

2、e authority of the Standards Board and comes into effect on 15 November 1993 BSI 07-1999 The following BSI references relate to the work on this standard: Committee reference AGE/30 Draft for comment 88/72250 DC ISBN 0 580 22447 3 Committees responsible for this British Standard The preparation of t

3、his British Standard was entrusted by the Agricultural Machinery and Implements Standards Policy Committee (AGE/-) to Technical Committee AGE/30, upon which the following bodies were represented: Agricultural Engineers Association British Agricultural and Garden Machinery Association Ltd. Health and

4、 Safety Executive Ministry of Agriculture, Fisheries and Food National Farmers Union Silsoe College Silsoe Research institute UK Irrigation Association National Rivers Authority Well Drillers Association Amendments issued since publication Amd. No. Date CommentsBS7562-5:1993 BSI 07-1999 i Contents P

5、age Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Informative references 1 3 Definitions 1 4 Sprinkle in-field equipment 1 5 Trickle/bubbler in-field equipment 7 6 Pipes and fittings 9 7 Suction and delivery pipework 14 8 Valves 15 9 Flow meters 18 10 Pump installations 18 11 App

6、lying chemicals 24 12 Safety 24 Table 1 A classification of irrigation systems used in the UK 2 List of references Inside back coverBS7562-5:1993 ii BSI 07-1999 Foreword This Part of BS7562 has been prepared under the direction of the Agricultural Machinery and Implements Standards Policy Committee

7、and contains recommendations on good practice in the planning, design and installation of irrigation schemes in the UK, together with information and guidance. It is intended for the use of engineers and farmers having some knowledge of the subject. It embodies the experience of engineers successful

8、ly engaged on the design and construction of irrigation schemes so that other reasonably qualified engineers may use it as a basis for the design of similar irrigation schemes. This Part of BS7562 contains information and represents good practice at the time it was written and, inevitably, technical

9、 developments may render parts of it obsolescent in time. It is the responsibility of engineers concerned with the design and construction of schemes to remain conversant with developments which have taken place since publication. This standard has been prepared in six Parts as follows. Part 1: Glos

10、sary of terms; Part 2: Guide for acquisition of site data; Part 3: Irrigation water requirements 1) ; Part 4: Guide to water resources; Part 5: Guide for irrigation equipment; Part 6: Guide for feasibility and implementation procedures. A British Standard does not purport to include all the necessar

11、y provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a 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, pages1to2

12、6, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on theinside front cover. 1) In preparation.BS7562-5:1993 BSI 07-1999 1 1 Scope This Part of BS7562 gives guidance on

13、the equipment required for irrigation schemes. It deals specifically with sprinkler and trickle/bubbler irrigation as the most common methods of irrigation in the UK and covers in-field irrigation equipment, pipelines, pump installations, and pump suction and delivery pipework. 2 Informative referen

14、ces This Part of BS7562 refers to other publications that provide information or guidance. Editions of these publications current at the time of issue of this standard are listed on the inside back cover, but reference should be made to the latest editions. 3 Definitions For the purposes of this Par

15、t of BS7562 the definitions given in BS7562-1:1992 apply. 4 Sprinkle in-field equipment 4.1 Introduction This is the equipment which is laid out, temporarily or permanently, in the field being irrigated. A wide range of in-field equipment is available but that commonly used in the UK is described in

16、 this British Standard. A classification is provided in Table 1. The selection of appropriate in-field irrigation equipment is based on many factors including capital cost, operating cost, labour requirements and suitability for the farm. 4.2 Water application devices 4.2.1 General The function of w

17、ater application devices is to apply water as uniformly as possible to the crop and soil. The most common application devices used to apply water are rotary impact sprinklers, guns and fixed spray heads. 4.2.2 Rotary impact sprinklers Rotary impact sprinklers are the devices most in use for spraying

18、 water. Sprinklers of varying sizes may be used on a wide range of irrigation systems including conventional and mobile lateral systems, seeTable 1. The design and performance requirements for rotary impact sprinklers are described in BS7459-1 and BS7459-2. Sprinklers should be operated within the m

19、anufacturers specified range of pressures for uniform water application. Sprinkler operation with too high a pressure will cause excessive break up of the water jet, loss of wetted radius and excess water applied near the sprinkler head. Low operating pressure at the sprinkler will result in inadequ

20、ate break up of the jet, large droplets and uneven application of water. The size of the nozzle(s) determines the sprinkler discharge and the wetted diameter. Nozzle diameters range from2mm to3mm up to50mm. Sprinklers may have one or two nozzles. Common trajectory angles for sprinklers are24 and30 m

21、easured from the horizontal. Such sprinklers are used on a wide variety of irrigation systems, including hand move and mechanical move equipment. Low angle sprinklers, having trajectory angles ranging from0 up to about15 produce a profile which is less subject to distortion by wind but may not be as

22、 uniform in application. Typical applications for low angle sprinklers include under tree orchard irrigation and centre pivots operating in windy conditions. The average application rate from the sprinklers (in millimetres per hour) should not exceed the basic infiltration rate (in millimetres per h

23、our) of the soil. This ensures that water infiltrates into the soil thus avoiding the problem of surface water run-off. The uniformity of water application is described by Christiansens coefficient of uniformity. Details of the coefficient and its measurement are provided in BS7459-2. The choice of

24、the most appropriate uniformity coefficient depends largely on the crop being irrigated. The spacing between sprinklers should be as recommended by the manufacturer and shown in performance tables. The wetted patterns from sprinklers should overlap to achieve an appropriate coefficient of uniformity

25、. The degree of overlap will vary according to the water application pattern and the wind conditions.BS7562-5:1993 2 BSI 07-1999 Table 1 A classification of sprinkle irrigation systems used in the UK Wind will distort the wetting patterns of sprinklers. The amount of distortion depends upon the wind

26、 speed and the size of the water droplets. The greater the wind speed and the smaller the water droplets the more distortion will occur. Wind distortion can be counteracted by spacing the sprinklers closer together but care should be taken as this may also increase the application rate. If the appli

27、cation rate exceeds the infiltration rate of the soil, run-off may occur. The direction of the wind may be an additional problem especially if the wind direction changes during the irrigation set. In this situation the best results may be obtained by ignoring the effects of wind altogether and opera

28、ting the sprinklers on their recommended spacings for low wind speeds. 4.2.3 Guns Guns are large rotary sprinklers which have a large wetted diameter. They are commonly used in mobile systems in the UK but they can also be used in conventional systems. Guns may be used on various irrigation systems

29、either fixed or mobile. They normally have discharges from10m 3 /h up to and above125m 3 /h and operate at pressures from2.0bar 2)up to and above8.0bar. The selection of the operating pressure depends upon nozzle size and type and droplet size required. Water droplet sizes from guns may be unaccepta

30、bly large for certain soil types and crops, causing damage to both soil and crop. Careful selection of nozzle diameter and type and operating pressure should be made to ensure that the resultant droplets are suitable for the soil and the crop. Gun nozzle diameters can vary from12mm up to and above40

31、mm. Two main types of nozzle are available; ring nozzles and taper nozzles. Ring nozzles are designed to produce acceptable droplet sizes at lower operating pressures. Taper nozzles are designed to produce the maximum wetted throw but droplet sizes are increased. The throw is not only affected by th

32、e operating pressure and nozzle diameter and type but also by the construction of the gun. The length of the range tube and its diameter, plus the use of straightening vanes inside the range tube, combine to affect the maximum throw. The application rate tends to be greater than for the small rotary

33、 impact sprinklers. The recommended spacing depends upon the wetted diameter, wind speed and direction and the required coefficient of uniformity. Gun spacing recommendations vary according to whether the gun is working on a grid system, a mobile unit or is used on a centre pivot or linear move. Sys

34、tems Water application devices Conventional systems portable hand move roll move tow line Mainly use small rotary impact sprinkers, but guns, fixed sprays and bubblers are also used semi-permanent sprinkler hop pipe grid hose pull permanent Mobile gun systems hose drag hose pull Mainly guns, but in

35、some cases the gun is replaced with a boom device with small rotary impact sprinklers or fixed sprays Mobile lateral systems centre pivot linear move Small rotary impact sprinklers or fixed sprays Spray lines stationary oscillating rotating Fixed sprays 2) 1bar = 10 5N/m 2= 10 5Pa.BS7562-5:1993 BSI

36、07-1999 3 Guns may be used for full or part circle irrigation. Full circle irrigation would usually be applicable to fixed grid irrigation systems. Mobile gun systems usually use part circle applications of270 to300 arc. Guns may also be used on the end of centre pivots and linear move machines to i

37、rrigate an arc of180 or less. There are two main types of drive systems used for rotating the gun. Impact drives operate using the water flow that leaves the nozzle moving an impact arm up and down or sideways causing the gun to rotate. Gear drives operate by passing a small quantity of the main sup

38、ply through or over a turbine gear drive assembly. This causes the gun itself to rotate via a gear mechanism. The drive mechanism may be affected by water quality. Care should be taken with gear drive systems to ensure that grit or other particles do not cause the drive system to fail. Filtration eq

39、uipment may be required for some systems. Guns normally operate with trajectory angles between18 and25 . Low angle guns may be used on applications where wind affects the gun performance, but the wetted diameter of the gun is reduced. Adjustable trajectory guns may be suitable for certain situations

40、 such as operating in high wind conditions where reduced wind drift is required. The part circle mechanism fitted to guns should provide adequate adjustment to cover the range of arcs required. Usually the range is between45 and330 . When returning to the start position, the reverse action of impact

41、 driven guns may occur at high speed. In this case the riser assembly should be strong enough to resist the forces. Operator safety should be considered where there is a risk that a gun may hit the operator when fast reversing. Slow reverse action sectoring devices are often now used on guns and the

42、se produce less strain on the connection assemblies. The thrust forces resulting from gun operation may be high due to the flows and pressures used and the construction of the riser is critical for correct gun performance. The riser strength should be sufficient with its support to prevent flexing o

43、f the riser which may cause either failure or poor gun performance. Risers used on grid systems should be designed with adequate support structures to ensure that when the gun is operating the riser is sufficiently stable. The riser should be of suitable diameter to ensure that the velocity of water

44、 through it is not excessive causing high turbulence which may affect the performance from the gun. Risers fitted to the trolley units used on self travellers should be sufficiently strong to resist breakage. The trolley base should be so designed that there is no risk of tipping over when operating

45、 under normal irrigation conditions. 4.2.4 Fixed spray heads Fixed spray heads may be used to apply water either to the total ground area or to a specific area around a plant. Spray jets may be used on conventional irrigation systems, such as under tree irrigation and also on centre pivots and linea

46、r move machines. 4.3 Sprinkle irrigation systems NOTEThe irrigation systems most commonly used in the UK are listed and classified in Table 1. 4.3.1 Conventional systems 4.3.1.1 General Conventional systems are the most common type of system in use and comprise pipes, small rotary impact sprinklers

47、and risers which are moved, often by hand, around the field to complete an irrigation. A characteristic of this type of system is that the pipes and sprinklers are stationary during irrigation and then moved between irrigations.BS7562-5:1993 4 BSI 07-1999 4.3.1.2 Portable The most basic and simplest

48、 system is the portable hand-move system. The pipes and sprinklers are all portable and moved by hand for each irrigation. As this tends to be very labour intensive, several developments have been made to this system to reduce the labour input. If the field layout allows, the laterals which carry th

49、e sprinklers should be laid along the contours to ensure as little pressure variation as possible caused by difference in height. The lateral may be operated down the slope provided that the maximum pressure variation along the lateral does not exceed20% of the sprinklers recommended operating pressure. If the slope would cause a greater pressure variation, then pressure regulators should be fitted to the sprinklers to produce correct operation. A pressure regulator may be fitted under the sprinkler inlet connecti