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The specifications and tests are based on existing international, European and national standards and other published references. They also draw on the indepth knowledge and experience of international sprayer standards of the experts assigned to the project and on the authors' experience of pesticide application in the developing world.

Specification Format

Specifications are in a modular format which was developed by the authors as the basis for the FAO document to guide FAO and other buying agencies in the selection of crop sprayers: "FAO Basic Guidelines for the Selection of Agricultural Pesticide Sprayers; June 1995".

Each module relates to a major component or a functional group of components from which consistent specifications for complete spraying machines can be compiled. The various modules for vehicle mounted and trailed sprayers are shown in Figure 1.

In the text, the modules are divided into numbered clauses each addressing a separate specification or requirement. The specifications do not dictate or prescribe engineering design; they define functional or operational requirements and should not restrict the design freedom of the manufacturer.

Wherever requirements or procedures are the same, then the same modules, clauses and wording have been used. This applies whether the sprayer is one of the four principal portable sprayer types or a tractor sprayer. For example the basic hydraulic nozzle module on spray quality applies to all sprayers.

Test Procedures

These are presented as stepbystep sequences to assist testers and to provide clarity and consistency. The aim is to use clear, uncomplicated language, without compromising technical precision.

FAO Approved Status

To implement this system, several, international Test Centres will be appointed by FAO. These centres will all follow the test methodology in this document and consistency and uniformity between centres will be monitored by FAO.

A key element of the system is the method for awarding "FAO Approved" status. The FAO compliance method to be used in the scheme is a simple YES/NO system. Where numerical values are included, these are based either on accepted norms in published standards or on the judgement of the authors and their advisers, always bearing in mind that the criteria used must relate to the needs of the practical field and factory situation. The system involves stating at the end of each clause in a specification (i.e. for each design or performance criterion), the action or series of actions which must be carried out. The actions are grouped into four categories: Check, Measure, Test and Test Procedure, which are defined as follows:

CHECK Where a simple observation or action is all that is needed to establish whether the sprayer complies or not, e.g.. "All hoses should be durably marked to indicate the rated pressure."

MEASURE Where a simple measurement e.g. volume, thickness, length, pressure is all that is needed.

TEST In some cases simple tests are required which are generally obvious and do not warrant written test sequences. e.g. "The sprayer should be stable and stand upright on slopes of 1 in 10, irrespective of the amount of liquid in the tank".


A sequence of step by step actions that should be followed as described in Part II of each volume.

* obligatory for sprayers with tankvolumes over 1000 l

Figure 4 : Tractor Sprayer Component Modules


The specifications in this volume apply to all terrestrial agricultural spraying equipment that is operated in conjunction with a tractor, or mounted on a purpose built chassis unit or within a multipurpose agricultural/horticultural vehicle. Throughout this document, for convenience, all these types of sprayer are referred to as the "sprayer".

The following specifications should be read in conjunction with Figure 4.


Sprayers should be safe, reliable and capable of working efficiently under practical field conditions that are often not ideal.

They should be robustly constructed from strong, durable materials that will not be prone to deterioration during field use, thereby adversely affecting safety and lowering efficiency due to corrosion, rust, distortion or excessive premature wear.

To attain "FAO Approved" status, a sprayer should comply with the following:

1.1 The sprayer unit should be securely attached to the vehicle system. CHECK

1.2 All shaft drives should be adequately guarded so that no moving parts are exposed. CHECK

1.3.1 Potential trapping points which could cause physical injury e.g. created by the boom folding or height adjustment mechanism, where practical, should be fitted with guards. CHECK

1.3. 2 In potential trapping point positions where guards are not practical, the sprayer should be fitted with appropriate, clear warning signs. CHECK

1.4 All handles, grips or hand holds should be at least 300 mm from any point of articulation. MEASURE

1.5 Hydraulic oil connections should be via connector systems that limit any leakage to a maximum of 2.5 ml for each make/break operation at pressures up to 175 bar.

TEST Leakage should be measured at maximum working pressure at each "make/break" action using clean, absorbent swabs of a known weight. The amount of leakage is measured by recording the weight increase after swabbing up the leaked liquid.

1.6.1 Vehicle mounted and trailed sprayers with a tank capacity of 1000 litres or more should be fitted with a low level filling system for both water and chemical. Where filling of either water or chemical is manual, it should be possible to add the chemical to the tank or fill the sprayer tank with water, with the operator either standing on the ground or on a purpose built platform with a minimum floor area of 0.5 m2. MEASURE

1.6.2 Platforms, where fitted, should be fitted with guard rails and be made from anti-slip flooring


1.6.3 Reach distances should not exceed 1.00 m vertically from the ground or platform and there should be a 0.3 m wide horizontal obstructionfree zone around the platform. MEASURE

1.7 The spray tank(s) filling system must permit safe, easy filling without overflowing or splashing at the stated maximum filling rate. TEST

1.8 The sprayer should not leak more than the specified limits under any working conditions at any of the recommended pressures or flow rates. TEST PROCEDURE 1

1.9 All external parts of the sprayer should be designed so that liquid is not retained on the surface of the machine and any chemical residues which accumulate can readily be washed off by a practical cleaning routine which should be defined in the sprayer handbook (see 1.16). CHECK

1.10 When operated to "empty", by spraying in the normal way, the amount of spray solution remaining in the complete machine (not just the tank) should not exceed 2.0% of the tank volume or 30 litres. TEST PROCEDURE 6

1.11 There should be no sharp edges, abrasive areas or sharp projections which could cause physical injury. CHECK

1.12 Where the sprayer is trailed it should be stable when disconnected from the prime mover. It should remain upright when positioned on a 1 in 10 slope in any direction and irrespective of the amount of liquid in the tank(s). TEST

1.13 Adjustments to the sprayer, routine maintenance, drainage and cleaning should be easily carried out without the use of specialised tools (i.e. tools specifically designed for the sprayer under test). CHECK

1.14 The manufacturer should provide a clear, illustrated, instruction manual in the language of the country in which the sprayer was manufactured and in English, French or Spanish (FAO official languages). Approval will only be given if the instruction manual is in the language used in the country where the equipment is sold. CHECK

1.15 The manual should contain procedures for:


It should also provide information on:


1.16 The sprayer should be clearly and durably marked to indicate: manufacturer's name and address, sprayer name, model and the year of manufacture. CHECK

1.17 The manufacturer must provide evidence to the test centre that a practical system is in place in the factory to record and store machine specifications and model details so that replacement parts can be accurately specified for a minimum of five years after it's date of manufacture. CHECK

1.18 All controls should be clearly marked and easily reached by the operator in the normal working position. CHECK

1.19 All parts of the sprayer, which come into constant direct contact with the spray liquid, including flushing tanks and induction hoppers where fitted, should be made of materials which are nonabsorbent and unaffected by approved pesticide formulations. TEST PROCEDURE 2

1.20 Those parts of the sprayer which are exposed to sunlight should be constructed of materials which do not degrade in U.V. light. CHECK

1.21 The sprayer, when mounted on a tractor if appropriate, should be constructed to withstand 1000 hours of simulated field use on a "rolling road " test rig (with the spraying circuit switched off and with boom sections in their normal working position) and still be capable of meeting the requirements of this specification . Routine maintenance should be conducted as required. TEST


There are often several tanks or similar structures fitted to a sprayer:

To attain FAO Approved status, a sprayer should be equipped with a main spray tank(s) and a clean water personal washing tank which should meet the specifications in MODULES 2 and MODULE 3 respectively.

Induction hoppers and rinsing tanks are mandatory on sprayers with a tank capacity of 1000 litres or more, and where they are fitted, they should comply with the requirements in MODULES 13 and 14 respectively.


2.1 Spray tank(s) should be constructed so that they are mechanically durable. TEST PROCEDURE 3

2.2 Spray tank openings should be fitted with close sealing lids which should be permanently attached to the tank. CHECK

2.3 Spray tank lids should be fitted with a positive mechanical closure system which can be operated with gloved hands (gloves for test purposes should be a minimum thickness of 0.5 mm). CHECK

2.4 Spray tank openings greater than 400 mm in diameter, or if rectangular of more than 400 mm x 300 mm, should be fitted with a grating which cannot be removed without using tools. CHECK

2.5.1 Spray tank openings which can be used for filling purposes should be fitted with a strainer with a maximum mesh aperture size of 1.0 mm. MEASURE

2.5.2 Spray tank strainers should be easy to remove and fit with gloved hands (see 2.3 re gloves). CHECK

2.5.3 Spray tank strainers should be close fitting and should not lift from their seating when filling. The gap between the strainer and the body of the tank should never exceed the filter mesh aperture size (1.0 mm.). MEASURE

2.6 Spray tanks should be clearly and durably marked with the "nominal", i.e. the maximum recommended filling level that should not exceed 95% of the total volume of the tank. MEASURE

2.7.1 The sprayer should be fitted with a means of indicating the level of liquid in the spray tank(s). CHECK

2.7.2 The liquid level indicator system should have a scale interval of no more than 20% of the nominal volume of the tank(s) and a scale accuracy of better than 1.5 % of the nominal tank volume. TEST

The scale should be checked at 5 levels by weighing the sprayer with 5 volumes of water in the spray tank to cover the range 10% to 80% of the tank capacity. TEST

2.7.3 The liquid level indicator(s) should be clearly visible to the sprayer operator from the driving position. CHECK

2.8 To facilitate cleaning of the spray tank(s), the internal and external surfaces should have a surface finish of better than ry = 100 mm which is a measure of surface roughness. MEASURE

2.9 The spray tank should incorporate a safe and convenient system to enable the liquid draining from the tank to be collected or discharged for safe disposal. CHECK

2.10 The amount of liquid remaining in the sprayer tank after routine draining should not exceed 1.5% of the nominal tank volume or 5.0 litres MEASURE

2.11 The pressure in the spray tank should not differ from atmospheric pressure by more than 0.3 bar under all working conditions.

TEST This test should be carried out using a manometer or pressure gauge connected so that the pressure in the top of the tank is measured. The gauge connection should be via a sealed pipe into the top of the tank and the test should be conducted with the lid tightly sealed.

2.12 The spray tank should be fitted with an agitation system to comply with the requirements in TEST PROCEDURE 4. The exception to this requirement is where the sprayer is designed to operate exclusively with control systems in which the diluent (water) and the concentrated pesticide are separately controlled. CHECK


3.1 The personal washing tank and associated plumbing circuits should handle clean water only and should be totally isolated from and independent of the main sprayer circuits which contain chemical solution. CHECK

3.2 The tank should have a minimum volume of 15 l. CHECK

3.3 The tank should be securely fixed to the sprayer. CHECK

3.4 It should be constructed from materials which will not rust or corrode thereby contaminating the water. CHECK


4.1 The pump should have sufficient capacity, when operating at its nominal rotational speed, to adequately supply all the nozzles when fitted with the largest specified nozzle size and operating at the maximum recommended working pressure, plus an additional allowance of no less than 20% to allow for nozzle tolerances and to provide tank agitation. TEST

4.2 It should be possible to remove the pump from the sprayer without draining the tank(s). CHECK

4.3 The pump should be permanently marked with:



5.1 Sprayers fitted with pumps which operate with valves should be fitted with a filter on the suction side of the pump with a maximum mesh aperture size of 0.5 mm. MEASURE.

5.2 All sprayers should be fitted with a filter in the pressure feed line with a maximum mesh aperture size of 0.5 mm. MEASURE

5.3 Pressure line filters should have a filter screen surface area which is large enough to permit the maximum required flow rate to pass through the filter when it is 50% sealed without increasing the pump operating pressure by more than 10% . MEASURE

5.4 All filters should be readily accessible for cleaning and maintenance. CHECK

5.5 It should be possible to clean all the filters without emptying the sprayer tank(s). CHECK

5.6 All hoses fitted to the sprayer should have a rated pressure equal to or greater than the maximum operating pressure of the sprayer plus 50% (see Section 5.1). CHECK

5.7 All hoses should be durably marked to indicate the rated pressure. CHECK

5.8 Hoses should be routed so that in the event of failure, the risk of operator contamination is minimised. They should not pass through the tractor/vehicle cab. When no cab is fitted, hoses close to the operator should be guarded to prevent operator contamination . CHECK

5.9 Any hose used to fill the sprayer tanks should be fitted with a strainer with a mesh size aperture not exceeding 1.0 mm. MEASURE

5.10 Hoses should be positioned so that there are no sharp bends (kinks) which could reduce the effective bore of the hose. CHECK

5.11 Hose connections should be easily adjustable with standard tools using gloved hands (see 2.3 re gloves) and should be able to be reconnected without leakage and loss of performance. CHECK


6.1.1 All sprayers should be fitted with a pressure safety device to prevent the pressure in any part of the circuit exceeding the maximum operating pressure by more than 20%. MEASURE

6.1.2 The pressure safety device should be designed so that when operated to reduce pressure, all liquid flows are directed back to discharge into the main tank. CHECK

6.2 The sprayer should be fitted with valves to isolate the supply of pressurised spray liquid to individual sections of the boom. CHECK

6.3 When operated to supply different combinations of boom section, the mean flow rate measured at any nozzle position (up to the largest nozzle size recommended) should not deviate by more than 5% of the nominal value. MEASURE

6.4 The delivery from a boom section should return to steady state within 10 s of a stepchange in demand being made. TEST PROCEDURE 5

6.5 There should be a single master control valve for turning on/off the supply to all boom sections. CHECK

6.6.1 Valves should be incorporated in the sprayer circuit to minimise the loss of spray liquid from nozzles once the liquid supply to a boom section has been turned off. The maximum leakage from a nozzle should not exceed 2 ml in a 5 minute period, commencing 8 seconds after the liquid supply to the boom sections has been switched off. MEASURE

6.6.2 The addition of the above antidrip valves in the nozzle supply line should not reduce the flow by more than 2.5% when operating with the largest size of nozzle recommended by the manufacturer. MEASURE

6.7 A "fail-safe" system should be incorporated into the sprayer to prevent back flow by siphoning while filling the spray and rinse tanks. TEST

6.8 Sprayers designed to operate with hydraulic pressure nozzles should be fitted with a pressure gauge that is clearly visible from the operator's working position. In the case of an analogue dial, this should have a minimum diameter of:

Other forms of display e.g. digital readouts, should be clearly visible. CHECK

6.9 The pressure gauge indicator should provide a stable reading. CHECK

6.9.1 Provision should be made in the design for the pressure gauge to be calibrated to an accuracy of ± 0.2 bar for gauges up to 10.0 bar and +/- 0.5 bar for gauges operating at higher pressures. MEASURE

6.9.2 The resolution of the pressure display system should also be 0.2 bar for gauges up to 10.0 bar and 0.5 bar for gauges used at higher pressures. MEASURE

6.9.3 When mounted in a tractor cab, the housing of the pressure gauge should be isolated from the spray liquid so that, in the event of failure leading to leakage, the operator is not contaminated. CHECK


7.1 Booms should be rigidly constructed so that all nozzles along the boom are supported at the same height above the target within 50 mm. MEASURE

7.2 The boom should be fitted with spray pipe lines and valves so that the supply of liquid to each boom section can be controlled independently. CHECK

7.3 The height of the boom above the ground should be adjustable with a minimum range of adjustment of 1 m. MEASURE

7.4 The force required to adjust the boom height should not exceed 250 N. MEASURE.

7.5.1 The mechanism for height adjustment should incorporate a "failsafe" feature so that in the event of failure of the height adjustment mechanism, the boom elevation will not change by more than 0.2 m. TEST

7.5.2 Where a manually operated system is used, this should be a self arresting type. CHECK

7.5.3 For powered height adjustment systems, the sprayer should be fitted with either:

7.5.4 Boom height settings of less than 0.5 m, should only be possible by manually overriding the 0.5 m stop control. CHECK

7.5.5 All height adjustment systems should be fitted with a locking device. CHECK

7.6 Booms more than 10 m wide should incorporate a mechanism which will isolate the boom from the rolling movements of the spray vehicle i.e. have some form of boom suspension which should comply with the requirements in TEST PROCEDURE 9.

7.7 The boom shall also have some isolation from the yawing movements of the vehicle. With the booms extended and the machine stationary, it shall be possible to displace the boom tip a horizontal distance of 20.0 mm for each 1.0 m of boom width without distorting the boom structure. CHECK

7.8 The boom should be fitted with a "breakback" device so that when the outer 10% width of the boom strikes a solid obstacle when travelling forwards, the boom "breaks back" without mechanical damage to the boom structure or any other part of the sprayer. After striking the obstacle, the boom should, automatically and quickly, return to it's original working position.

TEST This test should be conducted travelling in a forward direction at a speed of 2.5m/s.

7.9 When folded into transport positions, the boom sections should not:

7.10 The sprayer should be fitted with a mechanism to securely lock the boom sections in the transport position. CHECK

7.11 To minimise the risk of contact with overhead power cables during the folding operation, no part of the sprayer or boom should extend to a height of more than 5.0 m above the ground. MEASURE

7.12 Sprayers which extend to a height of more than 3.5 m above the ground, should be fitted with a warning sign pointing out the potential hazard from overhead cables. This sign should be clearly visible and easily understood by the operator. CHECK

7.13 The design of the boom should ensure that nozzles are protected from damage through contact with the ground. CHECK

7.14 Boom sprayers designed to operate with airassistance are required to meet all the standard requirements in 7.1 to 7.12. In addition, manufacturers of this type of sprayer should include in the sprayer manual (see 1.15):

7.15 Where a fan is used to generate air flows, then to comply, the sprayer should comply with the requirements in Module 9 of this document. CHECK


This module covers boom structures for air-assisted orchard and plantation sprayers.

8.1 The spray boom system should be designed to enable the spray liquid delivery to each side of the boom system to be independently controlled. CHECK

8.2 The boom should be rigidly attached to the sprayer. CHECK

8.3 Where the boom is designed to operate in different positions in relation to the air stream, then clear, detailed instructions should be included in the manual (see 1.16) describing the settings for effective operation in different crop and weather conditions. CHECK

8.4 Where systems are designed to operate without air assistance, detailed information must be included in the instruction book describing how to set up the sprayer to treat different target systems. CHECK

TR MODULE 9 - FANS ( for air- assisted spraying )

9.1 The drive to the fan unit should be able to be disconnected without affecting the mechanism for circulation and agitation of liquid in the sprayer. CHECK

9.2 The inlet to the fan should be designed and positioned so that when operating at maximum flow rate, debris is not drawn into the fan. CHECK

9.3 The lowest point of the fan inlet must be no less than 25 cm above the ground. MEASURE

9.4 The fan should be adequately and permanently guarded and grilles, where fitted, should have a maximum mesh aperture size of 25 mm. MEASURE

9.5 For selfpropelled machines fitted with a cab, the noise level, when the sprayer is operated at the maximum air flow rate, should not exceed 90 dBA at the operator's ear. MEASURE. Note - this noise level is higher than for some portable machines and has been set recognising the contribution of the vehicle and the sprayer together with the likely duration that operators will be subjected to this noise.


Where the sprayer is fitted or supplied with hydraulic nozzles, it is the responsibility of the sprayer manufacturer to ensure that these nozzles comply with the following requirements even though this information will normally originate from the nozzle manufacturer.

10.1 The sprayer manufacturer should provide in the instruction manual (see 1.15) information on:

N.B. The information on the above points should be provided by the sprayer manufacturer and will be verified by the Test Centre.

10.2 Dimensions of nozzle tips should be as shown in Figure 2. MEASURE

10.3 Output from a nozzle should be within ± 5% of the nominal output at any specified pressure. MEASURE

10.4 Output from nozzles with the same identity code i. e. which claim to have the same characteristics, when fitted to a boom, should not differ by more than ± 10% of the nominal output at any specified pressure. MEASURE

10.5 For hydraulic pressure nozzles, creating a flat fan spray pattern (including those termed "Even Spray") the volume distribution pattern should meet the requirements in TEST PROCEDURE 8.

10.6 For flat fan nozzles, the nozzle support systems should include a method of ensuring correct nozzle orientation within the holder. CHECK


These devices create a spray within a nozzle body via pressurised supplies of both liquid and air.

Where the sprayer is fitted or supplied with these nozzles, it is the responsibility of the sprayer manufacturer to ensure that they comply with the following requirements even though this information will normally originate from the spray generator manufacturer.

11.1 Sprayers fitted with twin fluid nozzles should be equipped with separate pressure control valves and gauges for controlling the liquid and air supplies respectively. CHECK

11.2 The sprayer manufacturer should provide data via the sprayer manual (see 1.15) indicating:

11.3 The flow rate from nozzles operating on a boom shall not vary by more than +/- 5.0% MEASURE.


Where the sprayer is fitted or supplied with these devices, it is the responsibility of the sprayer manufacturer to ensure that they comply with the following requirements even though this information will normally originate from the spray generator manufacturer.

12.1 In addition to the requirements specified in 10.1 above, the manufacturer is required to provide via the sprayer manual ( see 1.15) :

12.2 The spray generator should run for 50 continuous hours at maximum speed without needing maintenance. TEST

12.3 The flow rate and rotational speed of units mounted on a given boom assembly shall not differ by more than +/- 5.0 % MEASURE

Figure 5 : Dimensions of nozzle tips (according to ISO)


The following modules are essential to achieve FAO Approved Status for sprayers with tank capacities of 1000 litres or more. Where they are included, for the sprayer to be granted "Approved Status", the equipment is required to meet the following specifications.


An induction hopper/bowl is a conveniently located receptacle into which undiluted pesticide formulations can be safely poured or placed. A flow of water is then introduced into the hopper to dissolve or dilute the pesticide and transfer it into the main liquid flow circuit of the sprayer.

Where the sprayer is fitted or supplied with an induction hopper, it is the responsibility of the sprayer manufacturer to ensure that it complies with the following requirements even though this information may originate from the hopper manufacturer.

To achieve FAO Approved Status an induction hopper must satisfy the following requirements (based on British Standard 6356 Pt 8):

13.1. It should be designed to handle all forms of pesticide formulation that are intended for adding to water including liquids, powders, granules and soluble sachets and bags. CHECK

13.2 The hopper should have a minimum working volume of 151. MEASURE

13.3 The hopper should be clearly and durably marked to show the nominal, filling level, which should be no more than 95% of the total volume of the hopper. MEASURE

13.4 The hopper should be fitted with a lid which should be permanently and securely fixed to the hopper. CHECK

13.5 The hopper fill hole should have a minimum dimension of 250 mm. MEASURE

13.6. The height of the hopper fill hole should be between 0.51.0 m from the ground. MEASURE

13.7 There should be a minimum clearance zone (i.e. an area free from obstacles) around the hopper of 500 mm as shown in Figure 3. MEASURE

13.8 The hopper shall include a device for cleaning the original pesticide containers such that less than 0.01% of the original contents remain in the container following a defined operating procedure (i.e. 99.99% of container contents must be removed).

13.9 All the components of the induction hopper should be made of appropriate materials to comply with the requirement as specified in clause 1.15.

13.10 Instructions related to the operation of the induction hopper should be clearly and durably marked on the sprayer or hopper. CHECK

13..11.1The manufacturer should provide a clear, illustrated instruction manual as specified in 1.14 and 1.15. CHECK

13.11.2 In addition to the requirement in 13.9.1 above, the manual should specify:



14.1 This tank must be designed and incorporated into the sprayer so that it cannot be used by operators for personal washing or decontamination purposes. CHECK

14.2 The capacity of the flushing/ rinse water tank should be at least 10% of the main spray tank(s) capacity. MEASURE


15.1 Where manufacturers decide to fit protective clothing storage compartments, two compartments should be fitted; one for clean clothes and the other for contaminated clothes. CHECK

15.2 Protective clothing storage compartments should be located on the sprayer as far away as possible from the point of chemical loading. CHECK

15.3 The minimum internal dimensions of the compartments should be 450 x 450 x 300 mm. MEASURE

15.4 The compartments should be clearly and durably marked:

Figure 6 : Clearance zones around an induction hopper (based on British Standard 6356 Pt 8)

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