To clean concrete effectively, use a high pressure water jet blasting machine with a pressure at least 15000 psi and a flow rate of at least can achieve a perfect cleaning. Although higher pressures may be required to remove tough contaminants such as paint and heavy tire-skid marks, most power-washing contractors agree that 40000 psi will do the trick for almost all cleaning jobs. Several contractors recommend a power washer with a volume output of 5 or 6 gpm. When cleaning vertical surfaces, higher flow rates are not as critical because gravity helps contaminants flow from the surface.
Cleaning speed of water jet blasting
Cleaning speed also can be increased by using a rotary nozzle instead of a standard fan nozzle. To produce a fan pattern, standard nozzles deflect the water on an angle, which slows the water down. Rotary nozzles spin an undeflected water jet in a circular path, so the water leaves the nozzle with greater speed.
To improve cleaning speed on large flatwork areas, many manufacturers offer wheel mounted water blaster that resemble a lawn mower. Within the metal housing are nozzles mounted on spinning bars.
Cold water cleaning machineare cheaper, lighter, and simpler to use than hot-water units, which require a heavy heating coil and burner system to heat the water.
However, hot water jet blasting faster than cold water, and this rule holds true for power washing. Although cold-water units are suitable for removing dirt and often suffice for smaller, residential applications, most commercial power-washing contractors believe that using hot water is worth the added expense.
water jet blasting conrete diposal requirements
Depending on the power-washing chemicals used and the contaminants removed from the concrete, water runoff may be prohibited from entering storm sewers. Municipal codes vary greatly depending on the location. Some regulations, for example, require all discharge to be hauled to a waste-disposal site. Check with the local environmental protection Agency office for information on disposal requirements