hori/ontal plane. Vertical in-line pumps have their shafts vertical and thel)rmp is installed in the piping system the same way as for an inlinevirlve. Vertical barrel pumps usually are single stage, but horizontal,rod vertical drive shaft types can be of single-, double-, or multistagerlcsign, depending on the design conditions (pressure and tempera-Iure) of the process fluid, type of fluid (nonconosive, mildly corrosive,or highly corrosive), net positive suction head available, and to obtainllle desired delivery pressures.2.2.2 Reciprocatingl(cciprocating pumps are used where a precise amount of fluid isr('(luired to be delivered, also where the delivery pressure required islrigher than can be achieved with other types.The fluid is moved by the means of a piston that travels in a cylin(ler. After being drawn into the cylinder through an inlet valve, thelriston continues moving down the cylinder. As the piston moveslrirck up the cylinde! the liquid is discharged at a preset pressure, con-I r( )lled by a delivery valve.The liquid is ejected from the cylinder into the piping system inPrrlses, which are transmitted to the suction and discharge piping;tlrcfefore/ hold-down supports could be required on the piping\vstem on the suction and the discharge side of the pump.The three classes of reciprocating pumps are piston, plunger, and(lirphragm. Piston pumps generally are used where medium to high( l(,livery pressures are required, such as for a high-pressure flushing of\ ('ssel interiors and tanks. These can be obtained in multicylinderlorrn and can be single or double acting. Plunger pumps usually arerrsctl for metering or proportioning a fluid. Frequentlt a variable,,|ccd drive or stroke adjusting mechanism is provided to vary thellow as desired. Diaphragm pumps are invariably air driven and very( ()nrl)act, also no seals or packing is exposed to the liquid beinglrrrrrped, which makes them ideal for handling hazardous or toxic,r,1rrirlr. These o[len are used for sump pump oul.).2.3 Rotaryl(( )lirfy pumps are used to move hear.y or very viscous fluids. These, rrrploy rncchanical means such as gear, cam, and screw, to move thellrrirl.'llrc lwo malin classes of rotafy pumps are gear and screw. Gearlrrrrnps rrsrrally arc cmployed to pulrp oils and nonabrasive fluids.\( r('w l)unrl)s rrstrirlly alc rrscrl lo ptrrnll lrcavy viscotrs fltrirls anrl nonrlrt'rrsivt,slrrrIit's oI slLrtlgt,. n l)irrl lr'()rr nritinlitini ll 8o(xl a(c(,ss lo