This equates to nearly 900 hours of instruction per year, which is similar to or less than many U.S. states, including Florida, New York, Texas, and Massachusetts. At the middle school level (grades 6-8), Chinese students attend just under 1,000 hours of school per year, a figure similar to that of most U.S. states.
1 Hiring a professional pressure-washer costs about $0.08-$0.35 per square foot (depending on local rates), but can go as high as $0.40-$0.80 a square foot depending on the amount and type of stains, dirt, mold or other problems. Buying a basic residential pressure washer with an electric motor starts around $70-$200, depending on size and capacity. 2  A gas-powered residential model usually has a higher pressure rating than an electric machine, and is about $300-$1,000.
3,000 to 3,500 PSI power wash systems are the standard equipment in the contract power washing industry. A big reason for this is that while there is not much of a price difference between 2,000 PSI and 3,000 PSI washers, there is a tremendous difference in cleaning power.hemicals. Water Pressure-PSI. Water pressure from the pressure washer is measured in pounds per square inch or PSI. This pressure is the amount of force delivered to the surface being cleaned, and is the critical factor in breaking debris from the surface being cleaned.