We think it is important to dwell on the means of distribution of an insecticide, considering the topic of particular importance since often there is a certain lack of precision in dosages due to the confusion generated by considering the fulfillment of the percentage of ‘sufficient use to ensure compliance with the dose unitary.
First we analyze the most important parameters which identify a dispensing apparatus. They are the flow rate, the operating speed and the type of droplets issued (diameter and number of drops per square centimeter).
Obviously this should not make us forget other factors such as regulatory compliance, control precision, robustness, ease of maintenance, after-sales service and the availability of spare parts, as well as the power, weight, dimensions, the options supplied and delivery characteristics (distance and amplitude distribution).
Returning to the problem of dosage, if a product is to be used to a certain concentration, for example 1%, and is distributed with a pump to shoulder the dosage will vary according to the speed of execution. Experience tells us that with 10 liters of solution, depending on the operating conditions and the “step” of the operator, we can make from 80 to 200 square meters. It appears evident that, if we distribute our 10 liters of 1% in 100 square meters, the unit dosage will of 100 cc / sq while if we distribute them in 200 sqm the unit dosage will be at one half, ie 50 cc / m, and of course the result will be different.
It certainly is not always possible to perform an accurate measurement of square meters made, but you can do it empirically, but with sufficient accuracy, through an assessment of the degree of wet and leave behind us. For example, on a horizontal surface non-absorbent 100 cc / sq producing a veil of wet well visible that dries in a relatively long time (depending on temperature), while 50 cc / sq m are perceived by a thin layer of moist drying with ease. On a vertical surface, in the first case we observe the first signs of dripping, in the second does not.
The experience “annotated” allows the evaluation of intermediate situations, also in relation to the various types of surfaces more or less porous. The case studies are numerous and complicated in the case of spatial assessments, but our professionalism requires deepen this chapter with particular commitment, even though forces us to use even simple mathematical operations. To facilitate the task of the reader, within the limits imposed by the nature of the publication, we report in table an example of counting.
One last important tip is to carefully consider the type of nozzles because from them depends on the characteristic of the micelles provided and their uniform distribution. Having said all that remains is to state the most common types of electricity distribution, starting from the simplest.
For instance if you have to treat a warehouse of 200 mq high 4 meters /800 mc) with a thermal-fogger of 160 cc/min of capacity using a product that it’s effective with the concentration of 2 cc/mc you will obtain:
t = 400 x 2/160 = 5 minuts
Important: 5 minutes are long with a thermal-fogger buti f this time is not respected the insects (particularly the triboilum) will thank.
SPRAYERS
They are constituted by a pump which imparts a pressure to a liquid that is passing from a nozzle atomizes.
• Sprayers pump – pumps pre-compression: are known to all, especially for home use made of it. The tank usually ranges from 1 to 10 liters and the pump is driven by a kind of lever operated manually.
• Backed Sprayers: they are an extension of the previous system, the more dimensionie with a standard 10-liter tank; the pressure is obtained by maneuvering a lever.
• Pump Shoulder: similar to the previous but in this case the pressure is determined by an air bell realized by a pump that the operator maneuvers before dispensing. There are several types of models including highly professional documents with convenient kits to various needs.
Among the mentioned models also exist in the electric motor, either battery powered goal. Always among the sprayers there are of greatest power, in this case driven by a combustion engine also beyond the 10 HP of power with the theoretical course of more than 50 l / min. The tanks are sized in proportion to the power and can be up to 10 quintals.
ATOMIZERS
In this group are ascribed mixed systems water / air characterized by an impeller which creates a flow of air in which is injected into the liquid to be dispensed. Power is highly variable and the atomizers backed by a few horses up to the groups to truck-30-60-80 HP and over.
These powers involve dispensing capacity that allow for flow rates of more than 300 l / hour with horizontal thrown over 30 meters and vertical slightly lower. The operating speeds averages vary from 4 km / h to over 12 km / h; this entails an operational capacity of 120,000 m? / h (equal to 12 hectares) calculated on a speed of 8 km / h and a band of horizontal work of 15 meters; wanting a spatial assessment and estimating the working height of 12 m., it would be, subject to the parameters mentioned, of 1,440,000 cubic meters. ie just under a half million cubic meters now.
It now seems clear the necessary precision design (choice of formulations, percentage of use, estimation of unit dose needed, etc. Etc.) And the resulting operational carefully.
A group of equipment that is identity of the calculation method is made up of nebulizers, ultra low volume (ULV) and thermalfoggers. All with different powers and characteristics refresh www.mline.it, distribute mixed systems liquid-air.
Two clarifications are needed: the first for thermalfoggers, as they are able to distribute hot mist and for this reason require special products ready to use or by veicolarsi in suitable solvents; the second for ULV, which generally require liquids with low vapor pressure, as they deliver microdroplets (almost invisible) that too easily evaporate if that were not.
For special applications there are dusters can distribute dry powders; They are also cited the spray whose use requires more attention to what their spread in the home suggests.
Dosage per volume
Example of calculation:
Given a volume to treat, the unity concentration, the capacity of the equipment, to calculate the necessary time of delivery:
t = V x ppm/Q
t = time in minutes
V = volume to treat in cubic meter
Ppm = parts per millio or cc per cubic meter
Q = capacity in cc per minute
PERSONAL PROTECTIVE EQUIPMENT (PPE)
PPE means any equipment designed to be worn or held by the worker to protect him against one or more hazards likely to endanger the safety and health at work.
Obligation to use: PPE must be used when the risks can not be avoided or sufficiently reduced by technical preventive measures. Given the importance of the issue we reported a few lines of the law 81/08 on safety, it goes without saying that the Act or the subsequent amendments and additions must be known to all employers and workers for the specific obligations.
Given the sensitivity of the issue we simply indicate that the most common PPE used in pest control operations are gloves, glasses, headgear (hat or helmet, depending on the needs), shoes or boots and full-face masks or facial with its filters (remember that we are not concerned in the context of toxic gases otherwise we should mention breathing apparatus).
Two recommendations: we believe that the use of masks and filters provides for a specific instruction regarding the use and maintenance, and although not the work clothes generally considered PPE, could be in the context if it be necessary, for example, some specific features impermeability.
The attention of the legislator assumes, we stress as a conclusion, a constant verification of eligibility and a continuous attention to the problem for the adjustments as may be necessary.
Mario Alessi
