Aussie Blasters Service Fundamentals (pdf - 4.30MB) - Aussie Pumps

TYPICAL OPERATION AND REQUIREMENTSPressureThe pressure produced in a pressure washersystem is the result of forcing a known volumeof water through a known orifice size (spray tip).This pressure is measured in bar or pounds persquare inch (psi).FlowIn a pressure washer system the flow producedis determined by the speed that the pump shaftis rotated (rpm). The faster the shaft is rotatedthe higher the output volume. This water flow ismeasured in litres per minute.Nozzle OrificeSetting unloader valves for the requiredpressure of the machine depends entirely on thecorrect nozzle selection. The correct nozzleorifice can be selected to suit any specificpressure/flow combination using the chart onpage 5.Operators should be conscious that nozzle wearwill create a drop in pressure and an apparentmalfunction of the machine. The abrasive natureof water and the subsequent wear enlarges theorifice in the nozzle. The larger the orifice, theless pressure and the more danger ofsubsequent machine malfunction throughunloader failure.Further information on this subject is covered inthe Nozzle Selection Guide section.OperationThe pump which is motor driven draws water inthrough a series of inlet check valves as theplungers move back. As the plungers moveforward the inlet valves close, forcing the waterto travel through a series of outlet check valvesand to the pump outlet.When the water exits the pump the direction offlow is controlled by means of an unloader orregulating valve. A positive displacement pumpis always delivering a certain volume of waterwhether the spray outlet is open or closed so adevice is needed to control the direction of flow.This device allows the spray to exit through thespray gun or redirecting (by-passing) the flowback to the inlet of the pump if the gun is closed.As a safety device at least one pressure reliefvalve must be installed in the outbound side ofthe pump to protect against component failureand the development of dangerously highpressure.Note: Failure to install correct unloader valve orregulator device could result in serious injury andproperty damage.Chemical injectionCleaning chemicals or detergents may beintroduced into either the inbound or outboundflow of water. An inbound chemical injector usesthe pump=s ability to draw or suck fluid in tointroduce a chemical into the water flow. Anupstream injector allows chemicals to be appliedto the surface to be cleaned at normal high waterpressures. As any chemicals introducedupstream pass through the pump body, care mustbe taken to ensure the chemicals are compatiblewith the pump=s construction material andcomponents, such as seals.An outbound or downstream type of chemicalinjector uses the venturi system to draw chemicalinto the water stream. This type of injectorrequires low pressure to activate chemical flow.Low pressure is achieved by enlarging the outletorifice by changing to a larger spray tip or by anadjustable nozzle.There are advantages to using a downstreaminjector:1. Fewer pump component parts are exposed tothe cleaning chemicals which may extendsystem life.2. The operator can control the flow of chemicalsby changing the system pressure at thenozzle.3. Applying the chemical at lower pressure ismore economical as less chemical bounces offthe work surface.Hot water/steam cleanersHeated pressure washers and steam cleanersincrease the ability of high pressure water flow tobreak down dirt and grease. The cleaning actionof most detergents is also increased. Unitsincorporating a boiler are very complex andpotentially more hazardous than cold watersystems. Design of these systems requires manymore additional components and should bedesigned by qualified professionals with athorough knowledge of fuels, heat transfers, etc.4Aussie Aussie Pumps Pumps Bertolini Bertolini Pumps Pumps Service Service Guidelines Guidelines – July – 2011 July 2008