What You Need To Know Before Buying.

by the CCS Staff

Pressure washing is an efficient and cost effective method of cleaning a variety of surfaces, items and equipment found in most facilities. As long as moisture under pressure won't damage the surface and water run off is not a problem, high pressure washing should be considered as a viable cleaning option. It is a fast, easy and effective way to remove unwanted soil, oil, grease, gum, mildew, mold, debris and discoloration from both smooth and porous surfaces.

Common cleaning examples include sidewalks, driveways, parking garages, roofs, and building exteriors. Other tasks include cleaning restroom floors, walls and showers, floor mats, trucks, tractors, mowers, buses, equipment, carts, as well as paint prep and graffiti removal to name just a few of the possibilities.

What Equipment Is Right For You?

When it comes time to buy a pressure washer it's like buying a car or truck. You have many options, and these choices can drive up the cost.

Your decision as to what to buy should be based on how you plan to use the equipment. Some basic points to consider include such things as, do you want a stationary or portable machine? This is determined by whether you will take the machine to what needs be cleaned or bring what needs to be cleaned to the machine.

Many companies use industry terms rather loosely; you have to ask the right questions to determine what a company is selling and make sure you get a piece of equipment that is capable of doing the job you are buying it for.

Hot, Cold Or Steam

Next, do you need cold or hot water, a steam cleaner, or a combination system? This is determined primarily by your planned usage and budget. If you will be removing a lot of grease and oil, the hotter the better. The down side is a system with heat is more complex, dangerous, costly, has lower pressure and is generally avoided unless absolutely necessary. In some cases chemicals can be used in place of or in conjunction with heat to remove grease and oil. It is important to note that any chemicals used should be sprayed on separately or added to the system after the pump to avoid possible build up and damage to internal parts.

Combination systems are also available that can operate with cold water or generate hot water or steam. The downside again is cost and possibly emissions from the burner that generates the steam or hot water. Unless a system is totally electric it can not be used in buildings or confined spaces due to toxic emission such as carbon monoxide, although some companies now claim they have engines with zero emissions that can safely be used in buildings. Another approach is to position the machine outside the building, bringing into the area only the hose and the wand.

Power Systems

This brings us to the question of power for the system. Small cold water pressure washers generally power the pump with a combustion engine, such as gasoline, diesel or propane, with electricity also being an option. As for heating the water or generating steam this is usually done with kerosene, home heating oil, natural or LP (propane) gas. With some specialized equipment, electricity is used to heat the water to create steam, but this normally requires a 440 volts, three phase 100 amp power source.

Temperature

Steam cleaners operate at 300 degrees F and above at the heat source. At the end of the wand you get 240 to 270 degrees and wet steam. Hot water pressure washers operate at 240 degrees F at the heat source which means about 212 Degrees F at the end of the wand. In either case, what you get is very hot water or steam coming out the end of the wand.

Pressure

As for pressure, steam cleaners normally produce 200 to 300 PSI with some specialized units producing up to 2000 to 3000 PSI. Pressure washers normally operate in the 1000 to 3500 pressure range, with 2000 PSI being the most common with a limit of 212 degree F water temperature.

Hose Size

You basically have two options. If the unit your using pumps ten gallons or less per minute, a 3/8" hose with a 3000 PSI rating will be adequate for that pressure at a maximum of 240 degrees F. This would be considered a standard hose for most pressure washing applications. If your unit pumps over ten gallons per minute, a 1/2" hose is required, with a 4000 PSI rating. Hoses are designed with a safety factor of four times the rated pressure. Some combo units require a hose that is rated for 350 degrees at 3000 PSI. The bottom line is that the hose on the unit must match the system you are using to be safe and reliable.

Trigger guns are similar in that they are rated according to the pressure and temperature they are designed to be used at. They must be compatible with the system and hose they are being used with. These numbers are "up to" figures, meaning that a system with lower temperature and pressure rating will operate on a gun or hose with a higher rating. You just have a higher safety factor.

Gallons Per Minute

This is one of the two most important considerations when choosing a pressure washer, the other major consideration being horse power. Most commercial applications will work just fine with a unit that operates in the four to six gallon per minute range. For consumer or home use the standard is two to four gallons per minute.

The gallons per minute (GPM) and the pressure per square inch (PSI) determine the horse power needed for the motor or engine to operate effectively.

When using an electric motor to power the pump, the horse power should be between 1.5 HP and 10 HP. The commercial standard would be between 5 and 18 horsepower for a combustion engine and 3 to 5 horse power for an electric motor. If either the PSI or the GPM doubles, the horse power also needs to double.

Avoid units that have high PSI and low GPM volume. Such units are not a good commercial choice. An example would be 2000 PSI, 2 gallons per minute and 1.5 horse power. The hourly production rate will be low with this type of unit so in the long run the labor cost will be a lot higher because the water volume and horse power are not adequate to get a lot of work done in a short period of time.

Costs

You are better off paying more to purchase higher horse power and pay less attention to PSI. Spending 20% more will generally double the production of the unit. A low cost unit will drive up your labor costs. This is never a good trade off as labor is always your largest expense.

On an average you should expect to pay between $2000 to $5000 for a new commercial unit. Used washers sell for about half the price of new and are often listed in the equipment section of the classified ads in your local newspaper.

Safe Purchasing Guidelines

One machine may not fit all your cleaning needs. Generally speaking get horse power first, gallons per minute second, and PSI third. A good safe specification for most commercial uses would be 5 horse power, 5 gallons per minute with 1500 PSI, or 5 horse power, 4 gallons per minute with 2000 PSI. If you purchase in this range you will get a machine that can efficiently do most any job you will find in your facility. If you are going to use electricity for power, a 3 to 5 horse power motor is needed which may require a 220 volt circuit.

Nozzle Or Jet Specification

Another component is the size and degree of the pressure nozzle or jet at the end of the wand. This must also be matched to the job you are performing and the equipment you are using.

A variety of options are available and your local pressure washing equipment dealer can best advise you as to which nozzle will be most suitable for each application and unit. Nozzles are quick disconnect so they are easy to change for different jobs.

Some new technology in this area is now available. For concrete and sidewalks with gum a 0 degree rotating nozzle or turbo jet is very effective. It gives the illusion of high pressure with a small point size and operates very well at 2000 to 3000 PSI. In many applications a turbo nozzle can be used instead of chemicals, which lowers your costs and makes effluent run off or toxicity less of a consideration.

Another tool that is being widely used for flat horizontal surfaces looks like a lawn mower and has two high pressure rotating heads under a protective shroud. This unit can double or triple production to around 5000 square feet per hour on flat surfaces such as garage floors, sidewalks and roofs. With a turbo nozzle you can get a production rate of 1000 to 3000 sq. ft. per hour. With a fan jet nozzle of 15-40 degrees, the production rate could be as low as 1000 to 2000 sq. ft per hour.

Equipment Weight

Smaller cold water units will range in weight from 60 to 140 pounds. All portable units should come with large rubber tires and a handle for easy transport. Large units can weigh hundreds to thousands of pounds and are moved about with a fork lift or on a heavy duty trailer.

Other Issues

Issues that must be considered when looking at the possible use of pressure washing equipment include but are not limited to the following:

1. Run offóMost cities now have laws that govern how run off from pressure washing should be handled to avoid contamination of streams, lakes and the water supply. A permit may be required.

2. ChemicalsóAlthough not always required, they do speed up the process and in many cases result in cleaner surfaces. The down side is cost, toxicity, disposal and increased possibility of damage to surfaces as well as additional safety risks for workers.

3. NoiseóPower equipment makes noise. This must be taken into consideration if the equipment will be used during the day or at night near occupied buildings or residential units.

4. MaintenanceóThis is a powered piece of equipment that does require regular maintenance. This means that on a regularly scheduled basis you must tighten bolts, grease moving parts, inspect hoses and connections, change the oil, air filter, spark plug, and arrange to have the engine tuned up or rebuilt.

Test It Out

The best and safest approach is to have the seller bring the unit by, show you how to use it and leave it with you for a few days so you can put it to the test under actual working conditions. If this is not possible, consider renting a unit from a local rental yard to see which specifications are most appropriate for you needs. Proof is in the performance. Either it works or it doesn't and there is only one sure way to find outótry it.

For More Information

Contact your local sanitary supplier or check in the yellow pages under pressure washing equipment suppliers. The industry also has two magazines, several books, and seminars on the technical aspects of doing the work. A number of mail order suppliers also sell equipment at discount prices.

The industry association for contractors is Power Washers of North America (PWNA). The group has an annual convention each year and maintains a bulletin board on the internet for information exchange. The internet address is www.pwna.org or you can call 1-800-393-PWNA.

The industry association for pressure washing equipment manufacturers is Cleaning Equipment Trade Association (CETA). They also have an annual convention and trade show. Their telephone number is 1-800-441-0111.