SPRAYS AND OTHER MEANS OF CONTROL 



1887 



not give the purchaser the returns de- 

 sired with a minimum of expense for la- 

 bor and repairs. 



Some machines were never intended by 

 their designers to pump gritty spray so- 

 lutions, oil emulsions, caustic solutions, 

 or acid oils in emulsion form, and con- 

 sequently will not prove satisfactory. 

 The efficiency of a pump depends largely 

 upon the construction of its valves, valve- 

 seats, plunger, cylinder and stuffing box, 

 if built with the last. Air chambers are 

 also very important, hence these subjects 

 will be taken up under separate heads. 



The body or frame of the pump should 

 be heavy and strong enough to with- 

 stand hard usage and excessive strain. 

 Bearings are often too short, gears too 

 narrow and too light in weight, oil cups 

 are omitted where they are needed, and 

 the frame upon which the machine is 

 mounted is so light that it is warped and 

 buckled at every stroke of the pump. 



Air chambers are often omitted on 

 small pumps, and some large machines 

 are equipped with very small ones. A 

 barrel pump is greatly improved by the 

 addition of an air chamber five or six 

 inces in diameter and about two feet long. 

 Intake and hose supply-pipes must be 

 from a point near the bottom of the cham- 

 ber, or the value of the resilient column of 

 air is lost. The value of an air chamber 

 lies in the even pressure obtained, in 

 the taking away of the heavy shock upon 

 valves, and of the sudden strain often 

 put on other parts of a pump. A good 

 air chamber also eases the labor of the 

 man at the handle of the pump or of 

 the engine which is furnishing the power. 

 The liquid in the air chamber is often 

 unagitated unless some provision in de- 

 sign has been made so that the opening 

 of a nozzle cut-off agitates the liquid con- 

 tained in the air chamber, in addition to 

 the agitation caused by the supply of 

 liquid being forced into the chamber. 



Cylinders 



Of cylinders we have several types, but 

 no spray pump cylinder should be made 

 of cast iron or steel except for spraying 

 miscible oils and lime-sulphur solution. 

 Brass tubing of heavy weight and thread- 



ed to fit the cylinder head is quite a 

 common design. Some makers use a brass 

 tubing cylinder clamped between the cyl- 

 inder heads. Others use a solid cast 

 chamber with some form of a brass liner 

 or cylinder instead of the cast-iron one. 

 The most durable and the one least af- 

 fected by spray solutions is undoubtedly 

 the heavy, cast-iron cylinder enameled 

 with porcelain. The chief obstacle to the 

 use of such a cylinder has been to get 

 an even coat of enamel on the inside of 

 the machined cylinder-casting, or a plun- 

 ger-packing or cup which would have 

 sufficient resiliency to adapt itself to the 

 uneven wall of the cylinder. Some of 

 the manufacturers seem to have solved 

 this problem in a satisfactory way, while 

 others claim it is but a partial success 

 when used in the type of machine which 

 they manufacture. 



Valves 

 Kinds of valves are almost too numer- 

 ous to mention if one takes into account 

 the variations in each class. We may 

 divide them into four classes: ball, pop- 

 pet, swing-check and steam-check valves. 

 For the first, three materials are used: 

 rubber, steel and bronze, the latter ma- 

 terial being, of course, the most durable 

 for all-round work. Of the styles of pop- 

 pet there are many which may be class- 

 ified as follows: plain, square-faced pop- 

 pet valves with rod-guide to hold them in 

 position as in Fig 1 No. 1. No. 2 shows 

 how uneven is the wear on such a valve. 

 No. 3 shows a plain poppet valve with 

 wing-blades to right it instead of a rod. 

 No. 5 is a bevel-faced, wing-guided pop- 

 pet valve, which approaches a large ball 

 valve in durability and efficiency, when 

 it is made so that it will rotate. No. 

 4 shows a modified form of a wing-guided 

 poppet valve, with a rubber or leather 

 ring to improve its efficiency in helping to 

 retain the liquid above it. Fig. 2, Nos. 

 1 and 2 are ball valves. 



44 # 



Fig. 1. Poppet Valves 



