OTROS SEGUROS

In this category of sprayers, hydraulic pressure is thrust upon the liquid by the hand operated pumps. As a result, the liquid is forced through the nozzle in the form of a spray of droplets (diameter in the range of 300-400mµ). Sprayers of this type are high volume, high pressure and suitable for complete coverage of both ground and field crops.

13.4.1 Bucket type sprayer

It consists of a hand operated single or double acting pump (Fig.42), which may be placed into any ordinary bucket containing spraying solution. Plunger rod is hollow and serves as the compression chamber. Liquid is discharged in both suction and delivery strokes, hence a continuous application can be made. One hand operates plunger, while another hand keeps the pump in stable position. This pump is mostly made of brass. It is very light and easily handled and develops sufficient pressure to spray small gardens and low trees. It develops a pressure of 4 -10 kg/cm2.

Fig. 42. Line diagram of bucket type sprayer

13.4.2 Knapsack sprayer

It is very common type of sprayer, is provided with a pump and a large air chamber permanently mounted in a 9 to 22.5 lts tank. The handle of the pump extending over the shoulder or under the arm of operator, which makes it possible to pump with one hand and spray with other hand. Spray liquid is delivered through the delivery system, consisting of lance and nozzle, which is connected with the pump by a flexible hose. A uniform pressure can be maintained by keeping the pump in operation. It is generally carried on the back of the operator. It is quite useful for spraying small trees, shrubs and row crops up to 2.5 m height. These sprayers are useful because of their simplicity in operation, durability and for diverse use including spraying bushes of tea and coffee (Fig.43).

One man can spray about 0.4 – 0.5 ha in a day, thus spraying about 90 lts of spray liquid. A pressure of 3 -5 kg/cm2 is maintained in the pressure chamber.

Fig. 43. Line diagram of knapsack sprayer

13.4.3 Foot - operated sprayer

It is also called pedal pump (Fig.44). It consists of a plunger assembly, stand, suction hose, delivery hose and an extension rod with nozzle. One end of suction hose is fitted with a strainer and other end with a flexible coupling. Similarly, one end of delivery hose is fitted with a cut-off valve and other end with a flexible coupling. An additional container is required to hold spray fluid, as this sprayer does not have a built-in tank. Continuous pedaling is required for uniform spray. It can develop a pressure of 17-21 kg/cm2. It is easy to operate and can be used for spraying tall crops and fruit trees up to 4 m height. Sprayer can be used to spray trees up to 6 m height with additional hose.

13.4.5 Rocking sprayer

This type of sprayer consists of a lever operated pump assembly which rests on a wooden platform (Fig.45). Suction hose with a strainer is immersed in a separate container containing the spray liquid. Delivery system consists of a separate pressure chamber, a flexible hose, spray lance, and a spray nozzle. The lever attached to the pump is operated by the rocking- forward and backward movement of the handle. Pressure is developed in the pressure chamber, which may attain pressure of 14-18 kg/cm2. Such sprayers are used for spraying tall plants like coconut and arecanut trees, and sugar cane plants. Uniform spraying can be done if sufficient pressure is maintained in the pressure chamber. It needs two persons to operate the sprayer, one for operating the pumping system and another for the application of spray liquid. 13.5 Compression Sprayers

In these types of sprayers, air is compressed into the container by the compression air pump. When sufficient pressure is developed, then the delivery system is operated to obtain spray in the form of fine droplets. The compressed air forces the liquid through the nozzle and the desired type of spray is achieved. For this purpose, the tank is usually filled to three fourths of its capacity, leaving one-fourth volume for the compressed air. The pump is fitted vertically inside the container which acts as a force pump.

air

13.5.1 Hand compression sprayer

The compressed air sprayer consists of an air pump, is fitted vertically inside the airtight chamber. The outlet pipe is suspended in the liquid in the chamber, the end running into the bottom of the chamber, the other end is provided with a nozzle. The chamber is usually filled to three fourths of its capacity, leaving one-fourth volume for the compressed air. Before spraying, the pressure is developed by pumping air into the chamber and continued till sufficient pressure is built. When sufficient pressure is developed, then the delivery system is operated to obtain spray in the form of fine droplets. The tank capacity is usually 14 lts. Frequent pumping must be done to maintain the required pressure.

13.5.2 Hand atomizer

This is the smallest type of hand sprayer used to treat the plants in home garden or nursery and to apply fly spray in the house.