Sprinkler Nozzle Research Articles

Characterisation of two industrial deluge systems designed for the protection of large horizontal, cylindrical LPG vessels

The deluge systems on two industrial LPG tanks (of 50 and 60 tonnes capacity) plus that on a “full scale” experimental facility (nominal 13 tonne tank) have been evaluated in terms of the water distribution produced on the tank surface. The water distributions have been characterised in terms of water film depths and surface water flow rates at a number of locations across the tank surface using techniques described previously by Davies and Nolan (J. Loss Prev. Process Ind. (2004)). Vertical bands of high water density corresponding to zones of interaction between adjacent sprinkler spray envelopes were found for the 13 and 50 tonne LPG tanks, for both of which sprinkler nozzles were in alignment in adjacent rows. However, for the 60 tonne LPG tank, the sprinkler nozzles in adjacent rows were staggered, being offset to a distance of half of the longitudinal spacing between sprinklers. For this system, no distinctive water distribution pattern was observed, and the tank surface received a relatively uniform water coverage.

Experimental investigation of the parameters affecting the water coverage of a pressure vessel protected by a deluge system

Abstract Characterisation of the water distribution on the surface of liquefied petroleum gas (LPG) tanks with a protective water deluge in operation has involved the development of techniques to measure the water film depth and the rate of water flow across the tank surface. The devised instruments and the experimental measurements are reported. The water distribution was found to be uneven, with many regions of the tank surface receiving less than the recommended amount of water. The water supply pressure, the sprinkler yoke arm orientation and the stand-off distance between the sprinkler nozzles and the tank surface were all found to influence the resulting water distribution.

Digital image processing for determining drop sizes from irrigation spray nozzles

Abstract All the existing methods for measuring drop sizes produced by a sprinkler nozzle are either cumbersome, expensive or time consuming. Moreover, none could quantitatively express the relationship between drop size distribution and sprinkler head parameters viz. operating pressure and nozzle size. In the present study digital image processing technique has been applied to determine the drop size distribution from an irrigation spray nozzle. Image processing is the technique of automating and integrating a wide range of processes used for the human vision perception. The present study revealed that image processing technique can be successfully implemented for drop size measurement accurately. Being a novel technique, the method has some limitations for adaptation. These limitations can be very well contained through further research.

Sprinkler Head Maintenance Effects on Water Application Uniformity

The effects of wear on the ability of hand-move and side-roll sprinkler irrigation systems to maintain the designed water application rate and uniformity are of concern with regards to crop performance, water use efficiency, and environmental impact. Six hand-move and six side-roll sprinkler irrigation systems used under commercial crop production in Lane County, Oreg., were evaluated for equipment wear and performance. Individual sprinkler nozzle size and discharge rates were measured for each system and used in a computer model to estimate field application rate and uniformity. New nozzles were installed on six systems to compare potential application rate and uniformity with existing performance. Despite reducing the coefficient of variation in discharge between sprinklers from 10 to 2%, little increase in water application uniformity was attained. A 13% decrease in mean water application rate was documented after nozzle replacement. Ignored overapplication due to worn or mismatched nozzles results in overirrigation in both rate and total amount, which gives rise to the potential for increased surface redistribution and deep percolation, resulting in water and nutrient losses.

Modelling evaporation and drift losses in irrigation with medium size impact sprinklers under semi-arid conditions

A proper understanding of factors affecting evaporation and drift losses in sprinkle irrigation is important for developing water conservation strategies. For estimating drift and evaporation losses during the set sprinkler irrigation event, several outdoor single-sprinkler and block irrigation tests have been conducted. Various sprinkler–nozzle–riser height combinations were used and the variation of evaporation and weather conditions (i.e. air temperature, relative humidity, vapour pressure deficit and wind speed) was measured during the test. In addition, several on-farm solid set evaluations have been performed to evaluate evaporation and drift losses. Mathematical modelling is complex, and several simplifications should be assumed. A statistical approach has been used with these data to estimate losses using a linear model. The losses were estimated as a function of the sprinkler type, nozzle combination, vapour pressure deficit to the power of 0.5 and wind speed. Other climatic and operating factors did not have significant effect on the losses developed in this study. The model can be a useful tool to determine the irrigation timing as a function of environmental and operational conditions (e.g. working pressure, air temperature, relative humidity, etc.) in order to minimise evaporation and drift losses.

Sprinkler performance as affected by nozzle inner contraction angle

The discharge-pressure relationship for the orifice nozzle is essential for developing new sprinkler prototypes and designing sprinkler irrigation systems. In this work, the sprinkler nozzle inner contraction angle was varied from 20° to 90° to establish the relationship between discharge and pressure. The sprinkler nozzle discharge increases exponentially with increasing pressure. The discharge exponent is essentially independent of the nozzle contraction angle and can be taken as 0.5, while the discharge coefficient decreases significantly with increasing contraction angle. Sprinkler rotation speeds measured for different contraction angle nozzles decreased as the angle increased. Water distributions were tested indoors for various contraction angles. Sprinkler nozzles with contraction angles ranging from 20° to 60° produced approximately equal pattern radii and similar water application profiles, but the pattern radius was significantly reduced for contraction angles above 60°. The optimum inner contraction angle is about 30°.

A Method for Assessing the Risk of Zebra Mussel Dreissena Polymorpha Infestation in Industrial Fire Protection Systems

Though zebra mussels, first discovered in the Great Lakes in 1988, have frequently been detected in fire protection systems, the potential for large-scale infestations and blockage has not been established. It is clear, however, that even small numbers of mussels can cause problems in areas with small-diameter piping or in sprinkler system spray heads or nozzles. A method developed to determine the risk of mussel infestation within fire protection systems was implemented without interfering with system operation. The complexity of fire protection systems makes it useful to determine low-risk areas where remediation is not necessary, as well as high-risk areas where infestation is likely, allowing treatment at a greatly reduced effort, cost, and impairment of these protection systems.

Drop Size Distributions for Irrigation Sprinklers

A set of drop size distribution data is presented covering a wide range of sprinkler types including single nozzle impact sprinklers with straight bore and square nozzles, and sprayheads with various types of deflector plates. Drop sizes were measured by the laser-optical method and comparisons with other types of drop size measurement techniques are presented. Distributions are parameterized with an exponential function, and a method is provided to estimate the parameters given the sprinkler type, nozzle size, and pressure head.

INFLUENCE OF CLIMATIC FACTORS OVER THE DRIFT LOSS IN SPRINKLER IRRIGATION

A field experiment was conducted to assess the effect of climatic factors viz., wind velocity, relative humidity and atmospheric temperature over the drift loss under sprinkler irrigation. The influence of climatic factors, Sixteen combinations of four sprinkler nozzle diameters and four pressures were studied for each irrigation with ragi as test crop. It was found that only wind velocity had consistant, positive and significant influence on the drift loss.

Characterization of Rainfall under Center Pivot: Influence of Measuring Procedure

A simulation model of rainfall under center pivots was used to elevate center-pivot testing procedures. The model calculates rainfall parameters such as weighted mean and uniformity coefficient for various scenarios including the case of a voluntarily disrupted machine. Observed variations in rainfall parameters suggested modifications to standard procedures in order to improve accuracy. Those modifications include staggering rain-gauge position on the two radii of measure and a uniformity coefficient derived from a coefficient of variation calculated on weighted values, theoretically more sensitive than existing approaches. Such a procedure has been proposed as an improvement over the draft international standard ISO/TC23/SC18/DIS 11545, “Agricultural Irrigation Equipment—CentrePivot and Moving Lateral Irrigation Machines Equipped with Sprayer or Sprinkler Nozzles—Determination of Uniformity of Water Distribution.”

Simulating Water-Drop Movement from Noncircular Sprinkler Nozzles

The conventional approach for determining drag coefficient in the ballistic theory fits well for simulating water-drop movement emitted from circular sprinkler nozzles. This approach was checked for square and double-rectangular nozzles. The conventional approach does not work. Therefore the concept of an “apparent drag coefficient C d ” was introduced, and a new approach for determining C d was developed. It was verified that the spray distance for a specified droplet diameter calculated by the new approach fitted the observed one very well. The effect of droplet diameter; nozzle-shape, nozzle-size, and discharge coefficient; and pressure on C d was analyzed, and showed that C d is very sensitive to droplet diameter and nozzle-shape coefficient. The new approach was applied to investigate the influence of a sprinkler's trajectory angle on spray distance, and showed that both circular and noncircular nozzles reached their largest spray distances when the trajectory angle was around 37°. The effect of nozzle shape on the direction of droplet terminal velocity was also investigated.

Security: ‘choose wet or burned objects’

The deluge systems on two industrial LPG tanks (of 50 and 60 tonnes capacity) plus that on a “full scale” experimental facility (nominal 13 tonne tank) have been evaluated in terms of the water distribution produced on the tank surface. The water distributions have been characterised in terms of water film depths and surface water flow rates at a number of locations across the tank surface using techniques described previously by Davies and Nolan (J. Loss Prev. Process Ind. (2004)).Vertical bands of high water density corresponding to zones of interaction between adjacent sprinkler spray envelopes were found for the 13 and 50 tonne LPG tanks, for both of which sprinkler nozzles were in alignment in adjacent rows. However, for the 60 tonne LPG tank, the sprinkler nozzles in adjacent rows were staggered, being offset to a distance of half of the longitudinal spacing between sprinklers. For this system, no distinctive water distribution pattern was observed, and the tank surface received a relatively uniform water coverage.

Size Distribution of Oil-formulated Pesticide Droplets in Chemigation

The influence of mainline water velocity, injection port orientation, and sprinkler nozzle on droplet size distribution of oil-formulated non-emulsified pesticides was evaluated in a chemigation flow system. Volume median diameter and the percentage of oil volume in large droplets decreased as the mainline water velocity increased. The volume median diameter of droplets from sprinklers was smaller than those in the mainline and were influenced less by injection methods than by droplets in the system mainline. The results indicate that irrigation system design is important to the success of chemigation in agriculture.

Influence of Chemigation Parameters on Fall Armyworm Control in Field Corn

The application of pesticides in irrigation water (chemigation) is developing into a highly efficient and economical pest management strategy as the influence of application parameters are understood. In the current study, the effects of main-line water velocity, injection port direction, and sprinkler nozzle type were evaluated with two rates of chlorpyrifos to control fall armyworm larvae, Spodoptera frugiperda (J. E. Smith), in whorl-stage field corn grown under 0.6 ha center pivot irrigation systems. Chlorpyrifos injected into a main-line water velocity of 2.7 m/s generally gave as good or better fall armyworm control than when injected into a water velocity of 0.9 m/s regardless of sprinkler type. Upstream injection of chlorpyrifos formulated in non-emulsifiable oil resulted in better control of fall armyworm than did downstream injection. Chlorpyrifos applied with a 360@* spray sprinkler with coarse plates and nozzle orifice diam. between 3.6 and 9.5 mm at a main-line water velocity of 0.9 m/s gave the poorest fall armyworm control while an impact sprinkler gave the best control. The formulation droplet breakup in the main line and at the sprinkler were important factors in the distribution of insecticides to the target.

Nozzling Considerations for Center Pivots with End Guns

ABSTRACT THIS paper provides a technique for analyzing end gun applications on center pivots and looks specifically at several typical situations where they can be used. By use of field verified computer computational techniques, the effect of cycling an end gun on and off was studied in depth for a typical center pivot condition for considertion in selecting sprinkler nozzles for flow uniformity. Mean flow ratios, which are the actual flows at sprinkler locations divided by the theoretically ideal flow at that location, weighted in the radial direction for area covered, deviated from ideal by about IVi percent for both possible nozzling philosophies when operated in the converse fashion. The two philosophies are: (A) In-terior sprinklers are nozzled assuming that the end gun is in operation, and (B) interior sprinklers are nozzled assuming the end gun in not in operation. The converse fashions of operation are respectively: end gun not operating, and end gun operating. The mean flow ratios can be weighted in the cir-cumferential direction for the time of end gun opera-tions. This ratio is called the circular mean flow ratio (CMFR) and was found to deviate from ideal by 5.4 per-cent and 2.0 percent respectively. Because converse operation must occur when an end gun is cycled on and off, converse operation is unavoidable. The difference in deviations in CMFR's for the two philosophies indicates that one philosophy is superior. The superior nozzling philosophy is to nozzle interior sprinklers assuming the end gun is not in opera-tion.

Computer evaluation of sprinkler irrigation uniformity

A method for evaluating the water application rate (WAR) and uniformity coefficient (Cu) of overlapping irrigation sprinklers is given for realistic field conditions which includes wind drift of the sprinkler spray. The method requires as input — the geometry of the sprinkler arrangement, trajectories of water drops from the sprinkler nozzle as calculated by the equations of motion and the WAR distribution (discharge) profile of a single sprinkler experimentally observed under windless conditions. Wind direction with respect to the main sprinkler line is shown to have a small effect on Cu and is assumed to be parallel to the main line. Results show that the effect of wind drift of sprinkler spray on Cu can be neglected for wind velocities less than 1 ms−1 (Fig. 8). Analysis of simulated discharge profiles (Table 1) shows that the maximum value of the uniformity coefficient was obtained with triangular sprinkler discharge profiles at low values of spacing, changing to trapezoidal profiles as the spacing increases (Figs. 8 and 9). The effect of nozzle pressure on WAR was evaluated for the pressure range between 294 and 490 kPa and an optimum layout of overlapping sprinklers, designed to minimize the effect of wind drift and nozzle pressure on the uniformity of WAR distribution, is presented.

Injection of Insecticide in Irrigation Water To Control Corn Earworm and Fall Armyworm on Corn

ABSTRACT A scaled one-nozzle irrigation system was con-structed and tested for injecting insecticide into irrigation water for control of insects attacking corn. In-secticide was injected either inside the sprinkler nozzle or at the intake of the irrigation pump. The two injection methods gave equal insect control. Also, the injection of water-soluble and non-soluble materials into the system gave equal results. A formulation composed of 2 L of oil plus 1 L of Sevin-4 oil resulted in the same insect control as Sevin-4 oil alone. Application of 0.36 cm of irrigation water after completion of insecticide treatments did not significantly affect kill of corn earworm, Heliothis zea (Boddie). Field tests indicated that corn treated with water-soluble methomyl had significantly more wormfree ears than corn treated with stirofos (tested as Gardona 80 per-cent in oil). Oil used by itself resulted in significantly less wormfree ears than Gardona in oil.

On a Method of Uniformalizing Pressures by Orifices at Each Sprinkler Nozzle

On a Method of Uniformalizing Pressures by Orifices at Each Sprinkler Nozzle

Pest and disease control in blackcurrants and apples by the use of overhead irrigation sprinklers

AbstractIn field experiments on the effectiveness of overhead irrigation spraying of crop protection chemicals, an oscillating bar sprinkler was compared with hand spraying in post‐harvest applications of protective fungicides mancozeb (0.096% a.i.) with zineb (0.022% a.i.) for the control of blackcurrant leaf spot, Pseudopeziza ribis. Twin‐jet rotating sprinkler nozzles were compared with conventional automatic spraying of Cox's Orange Pippin apple trees in the application of a malathion emulsion (0.125% a.i.) for the control of apple‐grass aphid, Rhopalosiphum insertum and also in applications of pre‐blossom dodine emulsion (0.03% a.i.) and post‐blossom captan suspension (0.09% a.i.) for control of apple scab, Venturia inaequalis. All applications were made at a nominal rate of 2250 litres/ha (200 gal/acre).On blackcurrants, the hand spraying gave much better control of leaf spot and was shown by fluorescent tracer assessment to give more cover on the lower surfaces of the leaves than the sprinkler.On apple, the rotating sprinklers gave almost as good control of apple‐grass aphid and apple scab as the conventional automatic spraying. The malathion deposit levels, determined by g.l.c., on the flower trusses were also comparable, though the liquid volume distribution from the irrigation nozzles was uneven.