19o8 



MACHINERY 



MACHINKRY 



In most pumps ihoiv is a narrow s|>iu'o loft botwoon 

 tl\c iiistou iuul the iunor wall of tlu- cliaiiiln'r. This is 

 filUni with some ono of tho many kinds of packing- Oiu- 

 of tho (•lu\'i|H\st of those is iiiailo of loosolv roUod tow 

 strings :mii is sold as "oandK^wiokinj;.' Tho host 

 kinds aro ivmhinations of canvas and nihhor. It is 

 IHHir tHxmoniy to buy ohoai> paokiiif;. Tho host doos 

 not hist vory lonj; and tho tune lost iu replacing poor 

 paokiiip would pay tho slight extra cost of the better 

 prados many times over. 



No other p;irt of tho pvnnp nviiiiros :vs freqiiont 

 attention as the paokinn, thoroforo it is important 

 that pimips should bo so dosiiriied ;us to givo ready 

 aocess to tho iiacking and also that some moans should 

 be pro\-ido<l for keeping it tight against tho phmgor. 



Considering tho packing only, |nnni)s may bo tlividod 

 into two olasse*: outsiilo-packed and iiiside-packod. 

 An outside-packed pump is one in which the packing 



Pounds Pressure 

 2291. Diagram of the pressure and nozzle discharge. The amount of spray 

 discharged increases rapidly at low pressures but more slowly at higher pres- 

 sures. The amounts differ with different makes. 



is set on the in.side of the pumi)-oylinder and presses 

 against the outside of the plunger (Fig. 2289, E). Such 

 packing may usually be reached without removing the 

 plunger. An inside-packed pump is ono in which the 

 packing is on the face of tho plunger and presses 

 agairLst the inside of the pumij-cylinder (Figs. 22.S9, F, 

 and 2290) thus necessitating the removal of the plunger 

 before it can be renewed. 



All parts, such as valve^s, plungers, and eylindor 

 lining, which come in contact with spray materials, 

 ebould be of brass, as this does not corrode so rapidly 

 as steel. P"or inside-packed pumf)s, a bore<l cylinder is 

 truer than a drawn tube and so pumps much easier 

 because of the decreased friction. 



A single-action pump is one which draws in the 

 liquid as the plunger moves in one direction and drives 

 it out as the plunger moves back. There are r)nly two 

 valves on such a pumj). When two single-acting cylin- 

 ders are use<i on the samc^ jiumi) it is called a two- 

 cylinder, or duplex pump; one with three sucli cylinders 

 is called a triplex pump. 



A double-action pump is one in which the plunger, as 

 it moves forward, pushes the liquid out ahead of it 



and at the same tiino draws in liciuid back of it, then, 

 as the |)lungor moves back, this second amount of 

 li(lMi<l is i)usiio(l out and a now charge drawn in behind 

 the )ilungor. Thus, a com|)loto forward and backward 

 movement of the plunger shoulil discharge twice the 

 capai'ity of the eylindor. Such a pump requires four 

 \al\os and always hjis the packing on the face of the 

 plunger. 



Nozzles. 



Spray liciiiids were first apiiliod in a solid stream, 

 though this Wius usually fine enough to be broken into 

 drojis by the resistance of the air. The next step 

 forward w;is to place an obstruction at the end of tho 

 nozzle so that the stream, striking against this, was 

 .si)allorod out in fine drops. This method is still in use 

 in the bordoau.K nozzle, a device that gives a fan-shaped 

 spray whit^h at high pressures — two hundred jiounds or 

 mori! — is mist-like. It is not adapted to 

 fungicides, but may be used in applying 

 Ijoison sprays. 



In eddy-chamber nozzles, the liquid is 

 thrown into a whirling, or cyclonic, motion 

 in an eddy-chamber from which it is dis- 

 charged through a small o|icning. Particles 

 leave this opening in a direction tangent to 

 their previous notation, thus i)rofhicing a cone 

 of spray more or less uniformly filled. There 

 are two ways in which the rotating motion is 

 secured in the eddy-chamber: in one, the 

 liquid enters the chamber through openings 

 which have much the same pitch as the thread 

 of a screw; in the other, the liquid enters 

 through a passage tangent to the outer edge 

 of the eddy-chamber. The screw-thread noz- 

 zles are usually straight nozzles, that is, the 

 lines of entrance and exit are in the same 

 direction, and are best adapted to use in the 

 orchard. The tangent-entry nozzles are usu- 

 ally at right angles to the hose or spray-rod. 

 Some of them are well adapted to field- 

 spraying. 



At low pressures the quantity of liquid di.s- 

 charged by a nozzle increases rapidly with 

 increases of pressure, but at higher pressures 

 the increase in discharge grows less as the 

 pressure increases (see Fig. 2291). As the 

 pressure increases, the size of the spray 

 particles decreases. 



Tho front face of all eddy-chambers is made 

 by a thin disc in the center of which there is 

 a round hole, called the discharge-disc open- 

 ing. The smaller this opening, the finer are 

 the particles of spray and also the smaller the volume 

 discharged in any given time. A change from a small 

 to a large opening may double or triple the discharge. 

 The wear of a week of spraying may so enlarge the 

 disc-opening as to increase the discharge from 50 to 

 100 per cent. 



With hand-pumps it is usually desirable to use the 

 lowest pressun^ which will give a good spray; therefore, 

 with such pumps, the nozzle-<liscs should frequently be 

 renewed anfl only those with small openings used. The 

 discs cost but a few cents. Even with the same size 

 of disc-opening, difTerent makes of nozzles give a satis- 

 factory mist-siiray at various minimum pressures, 

 ranging from as low as thirty to as high as one hundred 

 Ijounds; therefore a knowledge of the mininuim pres- 

 sure at which a nozzle may be used is desirable when 

 one is using a hand-pumj) where the pressure may, at 

 times, run low. 



Sufficient emphasis has not been laid upon the impor- 

 tance of securing the nozzle best adapted to each pur- 

 jiose. From what has been said above, it is readily 

 seen that no small part of the success of the spraying, 

 especially when hand-i)umps are used, depends upon 



