CriticalEvaluation of Domestic Irrigation Equipment
ReportNo WSAA 119
The work of the Water EfficientAppliances Committee (WEAP) recognised the need for a study of domesticirrigation equipment. Since approximately half of the potable water supply isused to water gardens in southern Australia WEAP wished to investigate thedevelopment of a rating scheme for domestic irrigation equipment analogous tothe scheme in operation for plumbing equipment.
Water efficiency in an irrigationsystem depends on a number of factors. There are two main aspects toefficiency; firstly a water efficient system and secondly efficient operationparticularly in terms of scheduling, or the timing and duration of waterapplication events. In general terms the inefficiencies resulting fromincorrect operation of systems are more significant than the water lossesarising from the installation of faulty or inappropriate equipment.Notwithstanding this any future rating scheme must be developed with the understandingthat all aspects must be dealt with in a coordinated way. A rating scheme whichis introduced for equipment is likely to be ineffective unless the otheraspects of water efficiency are dealt with. Strategies must be developed toensure good design and installation practices are followed and peopleunderstand the basic principles of efficient garden watering.
High standards of system designand installation can be achieved by the support of industry certificationschemes for practitioners and by encouraging consumers to use the services ofcertified professionals.
Existing standards provideguidelines for equipment standards although some modification is necessary forthe types of equipment sold to the domestic market. As well as providing for standardmethods of classifying and describing equipment the standards provide for arange of test which can be conducted. The tests include;
Functional andoperational tests
Standards exist for allequipment types with the exception of controllers and sensors. Such equipmenthas the potential to make a significant contribution to water efficiency andthe development of standards in this area is important for efficient watering.
In this project tests werecarried out on a range of equipment including,
Sprinklers,rotating, impact and gear driven, pop-up and fixed sprays..
The varioustypes of equipment were subjected to the following tests;
Catch cantests for uniformity of application rate
Area and shapeof wetted pattern
Headlossmeasurements over a range of flows
Emission ratefor a range of inlet pressures
Coefficient ofvariation of product
Life testinginvolving repeated operation.
The majority of the sprinklersand sprayers tested had poor uniformity, the wetted patterns were significantlydifferent from the “advertised” patterns, and the radius of throw varied fromsample to sample. The coefficient of variation of the drippers varied from lessthan 5% to greater than 40%. The discharge rate over a range of inlet indicatethat many of the products are extremely inefficient, having discharge ratesvarying by a factor of three or four.
The hydrostatic pressure testsgenerally demonstrated that products are constructed to a quality sufficient towithstand the normal range of water pressures which are measured in domesticsituations.
As a result of these test arating scheme is proposed which sets criteria for product to be classified asA, AA, or AAA. The criteria proposed are:
A: Equipmenthas met criteria detailed in a standard encompassing general quality standards.
AA: Equipmenthas met standard requirements and can assist in improving water efficiency.
AAA: Equipment has met criteriaspecified in a standard and will contribute to improving water efficiency.
A strategy is proposed for theintroduction of the rating scheme. It is recommended that the rating scheme isdeveloped as part of a co-ordinated campaign, supported by resources andequipment to help people understand the basic principles of efficient homegarden watering.
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