Choosing a Pressure Washer
By
Robert M. Hinderliter, President
Delco Cleaning
Systems of
Phone: 800-433-2113, Email: delco@dcs1.com, www.dcs1.com
Commercial or
Consumer Washer
There is a wide range of pressure washing equipment available from consumer’s stores like Lowe’s and Home Depot to Industrial Supply Houses to Specialty Pressure Washer Dealers. The main difference between these sources is the support (consumer stores often do not know what they are selling or how to use it with little or delayed support) and the quality of the equipment. Typical consumer units are designed for a 100 hour life with 20 hour annual usage. This is a 5 year life for a typical consumer and a Dixie Cup Washer for the average contract cleaner. Typical Commercial/Industrial Washers are designed for several thousand hours of usage.
Because of the size and growth of the consumer market manufacturers are forced into redesigning their washers for this market. This makes it almost impossible for the contractor to distinguish between a consumer pressure washer designed for 100 hours of usage (20 hours/year for a 5 year life) and an industrial washer designed for several thousand hours of usage. The exterior of the washers look the same and the difference being in the quality of the interior parts. This is compounded by the fact that the flow (gpm - gallon per minute) and pressure (psi - pounds per square inch) may be identical. Therefore, for a one time short duration job a Dixie Cup pressure washer may be a better choice than renting a commercial pressure washer.
Choosing a Vendor will depend on how important the following items are to you: Technical Support before and after purchase, Reliability, Ease of Maintenance, Usage Requirements (one time only or every day), importance of operations, parts availability, maintenance and operational training, and entrepreneur support for starting and operating a business.
Typical consumer pressure washers have the following design parameters that are obvious to the buyer:
Typical industrial/commercial pressure washers have the following design parameters that are obvious to the buyer:
Water the Universal
Solvent
Water is called the “Universal Solvent” because it dissolves more substances than any other liquid including acids and bases. Pressure washing enhances the cleaning ability of water by adding heat, solvents and chemicals, abrasion (a combination of pressure, spray angle, rotating nozzles and brushing), and dwell time. With the proper application of these enhancers almost anything can be cleaned effectively.
Hot or Cold Water
The term “Hot and Cold Water Pressure Washers” refers to the temperature of the water being discharged and not the inlet water temperature. A hot high pressure washer takes cold inlet water and heats it to 200ºF in about one minute. This is referred to as instant hot water. Cold Water pressure washers do not heat the water.
For commercial operations where grease, oil, or gum is involved hot water is required to be competitive. Cold water, strong chemicals, and brushing will work on some applications but over 90% of successful contract cleaners use heat to cut chemical and labor expense.
Hot Water is a better solvent than cold water. Remember that clothes and dishes come cleaner faster and easier if they are presoaked and washed in hot water! The same is true in High Pressure Washing.
Common successful operations for cold water include deck and wood restoration, flat work cleaning where grease, oil, and gum are not involved (side walks and patios) , and vehicle washing with brushing (labor intensive).
Some cold water pressure washers can handle water heated to 140 to 160º F. See product literature for exact temperature. Hot water pressure washers heat the water after it has been pressurized by the pump up to a temperature of 200ºF.
When the trigger gun is off the water is bypassed back into the inlet of the pump. This closed loop bypass will reach 200ºF in about 5 minutes and steam in about 10 minutes. Therefore, the trigger guns should not be turned off for over 2 minutes. This applies to both hot and cold water pressure washers.
Cleaning Power (GPM,
PSI, ºF, Chemicals, & Nozzle Type)
The Power Washing industry generally expresses cleaning power in “Cleaning Units per hour” which is PSI x GPM x 60 (pounds per square inch x gallons per minute x 60 minutes per hour), or as Cleaning Units which is PSI x GPM. Either of the figures can typically be found on product literature. These figures leave out three very important items: chemicals, heat, and nozzle type. These three items typically can multiply the cleaning effectiveness several times.
There is presently no standard that takes into consideration all five factors for cleaning ability of a pressure washer. And total cleaning ability includes abrasion like brushing.
Most commercial hot water pressure washers can be used for any cleaning situation with the application determining the nozzles and chemicals used.
GPM
90% of the successful commercial operators use a flow volume of 4 gpm or more. Below 4 gpm there is not enough water volume to clean efficiently. While good cleaning can be done below 4 gpm the labor expense goes up drastically. This makes these washers suitable for consumer use where time is not a factor. Typically commercial pressure washers deliver 4 to 6 gpm. Consumer pressure washers typically deliver 1.5 to 4 gpm.
PSI
PSI (pressure) is determined by orifice size and flow rate (gallons per minute). The nozzle size standard is that a #4 orifice delivers 0.4 gpm at 40 psi and 4.0 gpm at 4,000 psi. And like wise for all of the other sizes. It takes a nozzle chart to interpolate all of the other flow rates and nozzles sizes.
The Pressure that contractors use varies a great deal. With a fan nozzle there is almost no pressure (cleaning power) greater than 3 feet from the nozzle. The pressure and temperature drop rapidly with the distance from the nozzle. You can test this by placing your hand in a fan spray 3 feet from the nozzle then slowly moving your hand toward the nozzle. Caution: Injury can result if you move your hand too close to the nozzle. Nozzles are designed for an effective range of 8 to 12 inches.
As a result of this rapid drop off in cleaning power a lot of contract cleaners will use 3,000 to 3,500 PSI to wash things that cannot stand that sort of pressure. They do this by varying the distance of the nozzle from the surface being washed. For less pressure they hold the nozzle back (increase distance from the surface being cleaned), and for increased pressure they hold the nozzle closer.
Larger companies will have washers that produce 4 to 8 GPM at 3,000 to 3,500 PSI, with 200 F. This much power is really needed for concrete cleaning while 1,500 to 2,000 is satisfactory for washing of vehicles. The more debris or dirt you are moving the more important GPM is. It takes water volume to move a lot of debris. Extremely large amounts of debris take fire hose volume of water.
Heat
has a great advantage where grease, oil and gum are concerned. A few
Vent-a-hood cleaners will use 310 F steam but these are mostly operators over
50 years old who learned to do Vents when that was the only thing available.
Younger Vent Cleaners (under 50 years old) will generally use 3,000 PSI at 200°F
units. However, some vent cleaners use electric 1,000 PSI cold water washers
hooked up to hot water (they hand scrape more). At the present time 3,000 to
3,500 PSI units are sort of the standard of the Contract Cleaner Market. A big
reason for this is that there is not much price difference between 2,000 PSI
and 3,000 PSI washers and there is a big difference in cleaning power.
The PSI for decks (wood) varies from 200 to 3,000 PSI. Too much pressure will
cause the wood to fur. If this happens you will need to sand with fine sand
paper or steel wool to knock off the furred surface. A lot of Deck Cleaners use
a variable pressure wand so that they can adjust the pressure as necessary at
the point of water impact. Using low pressure and letting the chemical do the
work will avoid furring the deck. Hint: use the under side of the deck to test
the PSI.
Nozzle Selection:
There are two selections that need to be made in choosing the proper nozzle:
the nozzle orifice size and the spray angle. This is normally expressed as
25055 or 2505 where the first two digits are the spray angle and the last 2 or
3 digits is the nozzle size (three digits for nozzle ½ sizes). The Spray Angle is the angle of the spray
width and the nozzle size determines the gallons per minute at a particular
pressure that a nozzle will pass. Therefore, in order to determine a nozzle
size you need to know the GPM (gallons per minute) and PSI (pounds per square
inch). To make this determination it is necessary to look up the information in
a nozzle chart like in "The Delco Wats Blaster".
By increasing the size you will reduce the PSI of your pressure washer and the
flow will remain the same. If you reduce the pressure of your washer with the
unloader you will decrease both the PSI and GPM and create undesirable and
dangerous conditions in the heater. Knowledgeable contractors reduce the PSI of
their pressure washers by increasing nozzle size in order to keep the GPM at
its maximum. To make this determination it is necessary to look up the information
in a nozzle chart.
Choices for spray angle for most nozzle sizes are 0, 5, 10, 15, 25, 40, and 65
degrees. 25 degrees fits the natural wash pattern of most contract cleaners.
However, some contract cleaners prefer a 40 degree spray angle because they can
hold the nozzle closer to the surface and obtain the same width of contact. The
advantage of this is that greater impact pressure and higher temperature is
delivered to the surface because the nozzle is closer to the point of contact.
However, you have to learn to keep the nozzle equal distance from the surface;
it’s like using a broom. Fan spray
nozzles are designed to be used at a distance of 8 to 12 inches.
A zero degree nozzle concentrates all of the cleaning power in a very small
pencil lead stream with a high degree of cleaning power at the center of
impact. This causes streaking similar to chicken tracks. Sometime you can see
the entire track of your wand wash pattern. The zero degree rotating nozzles
solve this problem. They have the power of a zero degree nozzle and the
coverage of a fan nozzle and when used properly do not leave wand marks
(tracers). The zero degree nozzles
rotate in a cone circular pattern at 1,000 to 2,000 rpm with a fixed or
adjustable spray angle.
Because zero degree rotating nozzles concentrate the cleaning power, they are commonly used on low volume cold water pressure washers. Also they are used in difficult cleaning situations such as vent-a-hoods, concrete cleaning, paint removal, and heavy equipment cleaning and on encrustations of carbon deposits.
Chemicals
There are many power washing chemicals including detergents, waxes, acids and brighteners designed for many applications. Read the labels carefully to select the proper chemical for a particular application.
Always read the MSDS (material safety data sheet) on cleaners before you use them for safety hazards and proper disposal options.
Chemical Dilution is largely a matter of personal preference.
For most
Gasoline & Diesel
Engines, & Electric Motors
Electric motors offer the most reliable maintenance free power source. While they are acceptable for light duty consumer use it takes 220 volts single or three phase to produce enough power for commercial use. This means that for the Mobile Contract Cleaner gasoline engines are the preferred power source. Diesel Engines use less fuel but are considerably more expensive. So they are only economical in high usage applications.
Pressure Washer
Mobility
The average gasoline engine skid mounted hot high pressure washer weighs in excess of 650 pounds. This means that these units are typically mounted in Bob Tail Box Trucks, pick ups, or mounted on flat trailers or in enclosed trailers. The advantage of trailer mounting is that the towing vehicle can be disconnected from the trailer for other uses.
Start Up Cost
Typical start up cost range from $200 for a consumer electric pressure washer to less than $10,000.00 for a commercial trailer mounted hot high pressure washer with start up accessories.
A search on the internet for mobile high pressure washer will result in over a hundred vendors.
Average Contractor
Hot High Pressure Washer
• 16 to 18 hp
• 4 to 6 gpm
• 3,000 to 3,500 psi
• 200ºF
•
Average Contractor
Cold High Pressure Washer
• 13 hp
• 4 gpm
•
Adding Pressure Washing for Profit
Adding power washing services has not been optional for several types of service contractors, like carpet cleaners, window cleaners, and air duct cleaners. They have been told by central purchasing that this service was going to have to be added as they were going to hire one contractor to provide all interior and exterior cleaning services. Other Cleaning Service Contractors have added pressure washing services because it is a natural add-on to their present customer base for both commercial and residential services. Normally this expansion included surface concrete cleaning (flat work, like parking garages, bank drive-thrus, shopping malls, fast food restaurant drive ways and side walks including gum removal, and store front including the parking areas), wood deck cleaning, exterior building restoration, kitchen exhaust cleaning, house washing, and vehicle fleet washing. With this in mind we would like to offer some things for consideration as you plan to expand your existing business or start a new one.
Professional Trade
Associations
Accessorizing for
Success
By: Larry Hinckley
Senior Technical Advisor
Delco Cleaning Systems of
Choosing the right accessories to compliment your pressure washer and to aid in the performance of your jobs can be a difficult task. Whether you are new in the industry or have been a mobile power wash contractor for years there are so many choices to be made that it is often difficult to decide what is needed and what isn’t. In your quest for knowledge you can visit some of the mobile power wash “Bulletin Boards” such as at www.dcs1.com and ask for help from other contractors. They will most generally welcome the opportunity to help you. If you prefer you can contact UAmCc and ask them to refer you to someone who might answer your questions.. Whichever choice you make it is important to the success of your company that you have the proper tools for the job. In searching for a good way to describe this situation I keep returning to the comparison between a new mechanic and a mechanic who has years of experience. If you will compare the size of their toolboxes you will notice that the more experienced mechanic will have a larger toolbox with a wider variety of tools available for him to use in his repair efforts. As you gain more experience in your chosen field you will learn that certain tools make your job easier, thus you will purchase these tools and have them ready for use when a certain situation arises. If one tool would do the job there would only be one drawer in a toolbox. As we all know this just wouldn’t work. In our efforts to be successful contractors we learn more about what we need to achieve this on each successive job. The following is a categorized list of tools that you may need for your individual efforts. It is not intended to be the final word on the subject. You may know of many things that you would like to ad to this list. Should you choose a Recycle System you will need a heavy-duty tandem axle trailer. The standard tandem axle trailer isn’t heavy duty enough.
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