Hot Water Pressure Washing

Summary
This recommendation is for hot water pressure washing of metal parts and fabrications where the wash solution is sewered after use. The method described below is "one-step cleaning". Parts are not rinsed with water following cleaning. Once all oils and other contaminants have been removed during washing, a water rinse is not required as Great Lakes Laboratories Prepaint Cleaners are non-filming and "paint compatible"

Equipment

• Hot water pressure washer - 1,500 to 3,000 psi
• Injector which allows high pressure injection
• 15° Wand Tip (routine cleaning)
• 0° Oscillating tip (rust, weld spatter, labels)
• Quick-Disconnect fitting for the wand tip

Product Selection

Method

1. Set temperature to 160°F at the wand tip.
2. Adjust injector so that 0.5 oz. of detergent is injected per gallon of water. Opening the injection valve 1/4 turn, is usually sufficient.
3. Adjust wand tip for horizontal fan spray
4. Begin at the top of the part and spray down using overlapping passes forcing soil down and off the part. Hold tip within 12" of the surface and at a 45° angle downward to "chisel" off soil.
5. Once clean, air-dry or force dry the part.

Troubleshooting
Flash Rust on hot rolled steel is usually caused by parts remaining wet for too long after washing.
Insufficient cleaning may result from low solution temperature, low solution concentration and/or incomplete spray contact with surface.
Avoid white streaking on clean parts by reducing solution temperature, strength, and/or wash time.

Cleaning Tips

1. To eliminate hand-tooling, switch to the 0° oscillating tip to remove rust, weld spatter, loose paint and adhesive labels.
2. Tilt parts to minimize soil collection on horizontal undersides by reducing the surface area of the "drip point". Tilting parts aids cleaning, draining and cuts drying time.
3. Hang parts on a swivel hook or place on a turntable. This allows the wash operator to remain in one position by rotating the part while washing. It also reduces wash time and overspray by keeping the spray directed into the wash bay.
4. To minimize operator fatigue, place the part so that the top is below eye level.
5. Bend wand 30° 4" behind the tip to allow easier access to difficult-to-reach areas. Use a tube bender to avoid crimping the wand.
6. Avoid flash rust after washing by drying parts immediately. For castings, blasted steel and other highly rust-prone surfaces, All Purpose Prepaint Degreaser will prevent flash rust bloom when allowed to dry on the surface. Parts can be painted without rinsing off the rust inhibitor.
7. Descale heating unit coil on a regular schedule to maintain pressure and extend coil life. Clogged coils reduce pressure.

4 Key Variables In Water-Based Cleaning

1. Time - Length of time the solution contacts the surface.
2. Agitation - Impingement of the solution on the surface.
3. Concentration - Strength of the solution
4. Temperature - Each +18°F temperature increase doubles cleaning rate

Sewerability
Great Lakes Laboratories Prepaint Cleaner wash solutions may be sewerable depending upon the local industrial wastewater regulations.

Contact your local regulatory authority for the regulations on industrial wastewater sewerability.

For Technical Assistance Call:
1-800-888-1105