Splash shadow

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Illustration: the spray nozzle (right) applies the spray material (blue) to the target area (left), the round obstacles create the spray shadow (marked red)

The area where no or only an insufficient amount of spray material reaches the spraying process is referred to as the spray shadow . The problem of spray shadows plays a role, for example, in agriculture and forestry , in construction , in the field of cleaning and disinfection , in painting or in forensic medicine . The spray shadow is also alternatively referred to as spray shadow , especially in the area of ​​cleaning and painting .

general definition

During a spraying process, the sprayed material is applied to the target area by means of a technical device, for example a spray nozzle or a valve. If there is an on-site object, a foreign body or (in agriculture, for example) a part of a plant between the nozzle and the target area, the spray material will stick to it or will be distracted, the area behind this object cannot be reached and remains largely untreated .

Examples

Agriculture and Forestry

Beet field shortly before the row was closed: a large-area application of protective agents only reaches a small amount of floor space

In agriculture, the occurrence of spray shadows poses a problem in weed control and plant protection measures. When the plant protection or weed control agent is applied from nozzles that spray the agent from above, the areas that are covered by the leaves of the plants become , poorly or not at all. This method is no longer effective at the time the series is closed. A remedy for farmers is the use of alternative application methods, for example under-leaf sprayers, double flat spray nozzles and so-called dropleg spray legs are used to reach the shaded areas under the plants.

Problems caused by splash shadows can also arise in forestry. If large amounts of round wood accumulate in the forest , for example after a storm or hurricane event, these are often temporarily stored in the forest in wet storage on piles . In order to protect the wood from damage caused by insect or fungal attack, it must be kept moist using irrigation systems. If the piles are stacked in such a way that the trunks lying further down are surmounted by those above, they are in the spray shadow and can no longer be reached by the water from the systems. This can lead to wood-damaging fungus or insect infestation, especially at the ends of the trunk.

Construction

In the construction industry, spray shadows can cause problems when using shotcrete, for example . The causes of spray shadows are, for example, an unfavorable spray angle or objects such as scaffolding poles that are located between the spray nozzle and the target surface. Even if there is reinforcement , it must be ensured that there are no cavities or areas with too little concrete behind it, which could later impair the strength and stability of the structure.

medicine

In forensic medicine , the term splash shadow appears in the terminology of blood trace analysis. Missing blood in places where traces should actually be present according to the environment are used by forensic doctors, for example, as an indication that something has been or has moved at the scene.

cleaning and desinfection

In the case of machine cleaning and disinfection, the splash shadow denotes those areas that cannot be reached by the cleaning agent. This effect occurs in dishwashers , for example , when the detergent gets stuck on components of the machine and does not get sufficiently onto the items to be washed. The same effect also occurs in the field of industrial cleaning of components or in the disinfection of medical and food technology systems and products. In these applications, the spray shadow can be prevented or reduced by technical solutions such as the use of movable spray nozzles or on-site adaptations.

Individual evidence

  1. ↑ Johannes Roeb, Heinz Bernhardt: Application method against residual weeds in sugar beet . In: LANDTECHNIK - Agricultural Engineering . tape 68 , no. 3 , 2013, p. 187 ff .
  2. ↑ Jörg Garrelts: Use the right nozzle without any problems! Brochure. Lower Saxony Chamber of Agriculture, Plant Protection Office (ed.), April 8, 2014.
  3. ↑ Roland Engesse: fungal infestation in nassgelagertem "Lothar" -Rundholz . In: Forest and Wood . No. 11 , 2003, p. 52 ff .
  4. ↑ Thomas Krause, Manfred Hoffmann: Number tables for the construction company . 8th edition. Vieweg + Teubner Verlag, Wiesbaden 2011, ISBN 978-3-8348-0934-6 , pp. 1153 ( limited preview in Google Book search).
  5. ↑ Oliver Peschel , Frank Ramsthaler, Markus Rothschild: Forensic blood trace pattern analysis . Lehmanns Media, Berlin 2015, ISBN 978-3-86541-795-4 , pp. 33 ff . ( limited preview in Google Book search).
  6. ↑ Wolfgang Ehrhardt: Washing up is a question of care. In: Allgemeine Hotel- und Gastronomie-Zeitung, July 6, 2012.
  7. ↑ Test liquid to determine splash shadows and to test the cleaning efficiency in the automatic cleaning of machines and systems and processes for producing the same. Patentblatt, February 3, 2011, accessed October 19, 2016 .
  8. ↑ Michael Stöcker: Technical cleanliness - automatically clean. Scope Online, May 27, 2015, accessed October 20, 2016 .