Pressure washer
Encyclopedia
A pressure washer is a high pressure mechanical sprayer
that can be used to remove loose paint, mold, grime, dust, mud, and dirt from surfaces and objects such as buildings, vehicles, and concrete road surfaces. The volume of a pressure washer is expressed in Gallons Per Minute, which is designed into the pump and not variable. A pumps pressure, expressed in Pounds per Square Inch, is also designed into the pump but can be varied by adjusting the unloader valve. Machines that produce pressures from 750 to 30,000 psi
(50 to 1,200 bar), or more, are available. A pressure washer differs from a parts washer
in that a parts washer typically uses high-volume, lower-pressure (20-150 psi, 1.4-10 bar) cleaning solutions in an enclosed cabinet to clean dirty parts. The impact pressure generated in a parts washer is typically higher than a pressure washer. Additionally, the environmental issues in an enclosed parts washer are less because all of the solution is contained unlike a pressure washer.
The basic pressure washer consists of:
Just as a garden hose nozzle
is used to increase the velocity of the liquid, a pressure washer adds its own power to create high pressure and velocity. The pump cannot draw more water from the pipe to which the washer is connected than that source can provide. Moreover, the water supply must be adequate for a given machine connected to it, as water starvation leads to cavitation
damage of the pump elements.
Several different types of nozzles are available, each useful for a particular application. Some nozzles cause the water jet to be ejected in a triangular plane (fan pattern), while others emit a thin jet of water, which spirals around rapidly (cone pattern). Nozzles that deliver a higher flow rate lower the output pressure. Most nozzles attach directly to the trigger gun.
Some pressure washers, in combination with a particular nozzle, allow detergent
to be introduced into the water stream, assisting in the cleaning process. Two types of chemical injectors are available — a high-pressure injector that introduces the chemical after the water leaves the pump (a downstream injector) and a low-pressure injector that introduces the chemical before water enters the pump (an upstream injector). The type of injector used is related to the type of detergent used, as there are many chemicals that will damage a pump if an upstream injector is used.
Pressure washers are dangerous tools and should be operated with due regard to safety instructions. The water pressure near the nozzle is powerful enough to strip flesh from bone. Particles in the water supply are ejected from the nozzle at great velocities. The cleaning process can propel objects dislodged from the surface being cleaned, also at great velocities. Pressure washers have a tendency to break up tarmac
if aimed directly at it, due to high pressure water entering cracks and voids in the surface.
Most readily available consumer units, commonly found online or at hardware stores, are electric- or petrol-powered. The electric ones plug into a normal outlet, use cold tap water and typically deliver pressure up to about 2,000 psi (140 bar). Petrol powered units can often deliver twice that pressure, but due to the hazardous nature of the engine exhaust, they are unsuitable for enclosed or indoor areas. Some models can generate hot water, which can be ideal for loosening and removing oil and grease.
In its extreme high pressure form, water is used in many industrial cleaning applications requiring the removal of surface layers as well as dust-free cutting of some metals and concrete. For exterior applications, gas or propane powered pressure washers provide enhanced mobility not available in electric models, as they do not require use in proximity to an electrical outlet. However, for indoor applications, electric pressure washers produce no exhaust and are much quieter than their gas or propane powered counterparts.
High-pressure water at medium pressure, in combination with special chemicals, aids in the removal of graffiti
. This process (especially when the water is hot) is used as a quick rinser of the softened graffiti. Sometimes people use a pressurized mixture of air/sand or water/sand to blast off the surface of the vandalized area, thus etching the surface and therefore making it extremely difficult for anyone to ever use high-pressure cleaning as a follow-up process. Sandblasting, when used in graffiti removals, often overcleans a surface and is capable of leaving a permanent scar on the building surface.
Sprayer
A sprayer is a device used to spray a liquid.In agriculture, a sprayer is a piece of equipment that spray nozzles to apply herbicides, pesticides, and fertilizers to agricultural crops...
that can be used to remove loose paint, mold, grime, dust, mud, and dirt from surfaces and objects such as buildings, vehicles, and concrete road surfaces. The volume of a pressure washer is expressed in Gallons Per Minute, which is designed into the pump and not variable. A pumps pressure, expressed in Pounds per Square Inch, is also designed into the pump but can be varied by adjusting the unloader valve. Machines that produce pressures from 750 to 30,000 psi
Pounds per square inch
The pound per square inch or, more accurately, pound-force per square inch is a unit of pressure or of stress based on avoirdupois units...
(50 to 1,200 bar), or more, are available. A pressure washer differs from a parts washer
Parts washer
A parts washer is a piece of equipment used to remove contaminants or debris, such as dirt, grime, carbon, oil, grease, metal chips, cutting fluids, mold release agents, ink, paint, and corrosion from workpieces...
in that a parts washer typically uses high-volume, lower-pressure (20-150 psi, 1.4-10 bar) cleaning solutions in an enclosed cabinet to clean dirty parts. The impact pressure generated in a parts washer is typically higher than a pressure washer. Additionally, the environmental issues in an enclosed parts washer are less because all of the solution is contained unlike a pressure washer.
The basic pressure washer consists of:
- An electric motorElectric motorAn electric motor converts electrical energy into mechanical energy.Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force...
or gasoline (petrol) enginePetrol engineA petrol engine is an internal combustion engine with spark-ignition, designed to run on petrol and similar volatile fuels....
that directly drives a water pumpWater PumpWater Pump is one of the neighbourhoods of Gulberg Town in Karachi, Sindh, Pakistan. It is near main Water Pump that supplies fresh water to the city of Karachi.... - A high-pressure hoseHoseA hose is a hollow tube designed to carry fluids from one location to another. Hoses are also sometimes called pipes , or more generally tubing...
- Trigger gun-style switchSwitchIn electronics, a switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to another....
Just as a garden hose nozzle
Nozzle
A nozzle is a device designed to control the direction or characteristics of a fluid flow as it exits an enclosed chamber or pipe via an orifice....
is used to increase the velocity of the liquid, a pressure washer adds its own power to create high pressure and velocity. The pump cannot draw more water from the pipe to which the washer is connected than that source can provide. Moreover, the water supply must be adequate for a given machine connected to it, as water starvation leads to cavitation
Cavitation
Cavitation is the formation and then immediate implosion of cavities in a liquidi.e. small liquid-free zones that are the consequence of forces acting upon the liquid...
damage of the pump elements.
Several different types of nozzles are available, each useful for a particular application. Some nozzles cause the water jet to be ejected in a triangular plane (fan pattern), while others emit a thin jet of water, which spirals around rapidly (cone pattern). Nozzles that deliver a higher flow rate lower the output pressure. Most nozzles attach directly to the trigger gun.
Some pressure washers, in combination with a particular nozzle, allow detergent
Detergent
A detergent is a surfactant or a mixture of surfactants with "cleaning properties in dilute solutions." In common usage, "detergent" refers to alkylbenzenesulfonates, a family of compounds that are similar to soap but are less affected by hard water...
to be introduced into the water stream, assisting in the cleaning process. Two types of chemical injectors are available — a high-pressure injector that introduces the chemical after the water leaves the pump (a downstream injector) and a low-pressure injector that introduces the chemical before water enters the pump (an upstream injector). The type of injector used is related to the type of detergent used, as there are many chemicals that will damage a pump if an upstream injector is used.
Pressure washers are dangerous tools and should be operated with due regard to safety instructions. The water pressure near the nozzle is powerful enough to strip flesh from bone. Particles in the water supply are ejected from the nozzle at great velocities. The cleaning process can propel objects dislodged from the surface being cleaned, also at great velocities. Pressure washers have a tendency to break up tarmac
Tarmac
Tarmac is a type of road surface. Tarmac refers to a material patented by Edgar Purnell Hooley in 1901...
if aimed directly at it, due to high pressure water entering cracks and voids in the surface.
Most readily available consumer units, commonly found online or at hardware stores, are electric- or petrol-powered. The electric ones plug into a normal outlet, use cold tap water and typically deliver pressure up to about 2,000 psi (140 bar). Petrol powered units can often deliver twice that pressure, but due to the hazardous nature of the engine exhaust, they are unsuitable for enclosed or indoor areas. Some models can generate hot water, which can be ideal for loosening and removing oil and grease.
Uses
In its extreme high pressure form, water is used in many industrial cleaning applications requiring the removal of surface layers as well as dust-free cutting of some metals and concrete. For exterior applications, gas or propane powered pressure washers provide enhanced mobility not available in electric models, as they do not require use in proximity to an electrical outlet. However, for indoor applications, electric pressure washers produce no exhaust and are much quieter than their gas or propane powered counterparts.
High-pressure water at medium pressure, in combination with special chemicals, aids in the removal of graffiti
Graffiti
Graffiti is the name for images or lettering scratched, scrawled, painted or marked in any manner on property....
. This process (especially when the water is hot) is used as a quick rinser of the softened graffiti. Sometimes people use a pressurized mixture of air/sand or water/sand to blast off the surface of the vandalized area, thus etching the surface and therefore making it extremely difficult for anyone to ever use high-pressure cleaning as a follow-up process. Sandblasting, when used in graffiti removals, often overcleans a surface and is capable of leaving a permanent scar on the building surface.
Types
Pressure washers are classified into following groups based on the type of fuel/energy they consume.- Electric pressure washer
- Diesel pressure washer
- Petrol pressure washer
- Gas pressure washer
- Ultra high pressure washer
- Hydraulic high pressure washer
- High pressure steam cleaner