Ultrasonic Cleaning: Content Restoration Cleaning Technology
Highly efficient and effective cleaning is a requirement in content restoration after a fire, wind or water related disaster. In the case of fire, smoke and ash contaminate everything in their path. Smoke residues are chemically active and cover and stick to a variety of different surfaces. These smoky chemicals can permanently stain surface finishes, textures and fabrics. Luckily, One Call is a restoration company equipped with the knowledge and equipment to handle such a sticky situation.
The phasing out of environmentally hostile chlorofluorocarbons globally has eliminated the viability of many cleaning processes previously used for restoration cleaning and performance and warranty requirements lay a greater stress on the need for a high quality, predictable, repeatable, cleaning outcome. Ultrasonic cleaning fills that void.
Ultrasonic cleaning is a technology that uses high frequency sound waves to agitate an aqueous or organic medium (cleaning chemicals or water) that in turn acts on contaminants adhering to substrates like metals, plastics, glass, rubber and ceramics. Contaminants can be smoke, soot, dirt, oil, grease, mold release agents, biological soil like blood, and so on.
Direct ultrasonic cleaning occurs when the parts are cleaned in a cleaning solution which fills the cleaner, usually inside a perforated or mesh basket. The limitation of direct cleaning is that a solution must be chosen that will not damage the ultrasonic cleaner.
Indirect ultrasonic cleaning involves placing the parts to be cleaned in an inner non-perforated tray or beaker that often contains a solution that the user may not want directly filling the ultrasonic tank. Choosing the right combination of ultrasonic cleaner and cleaning chemistry for content restoration can be a challenge. That which works best for content damages in a fire by smoke or soot may not be appropriate for water damaged content from a flood.
"Cavitation" is the rapid formation and collapse of millions of tiny bubbles (or cavities) in a liquid. An ultrasonic cleaner consists of an ultrasound generator along with special transducers mounted on the bottom of a liquid-filled stainless steel tank. The generator and transducer create alternating waves of compression and expansion in the liquid at extremely high speeds, usually between 25 and 130 kHz.
In the compression phase, the great amount of pressure exerted on the newly expanded bubble leads to a sudden implosion of the bubble. The liquid molecules collide releasing a vast amount of impact energy that rapidly increases the local temperature producing a high-energy liquid stream that collides with the surface of the object being cleaned. This collision agitates contaminants adhering to the surface, effectively and efficiently dislodging them.
There are many considerations important to ultrasonic cleaning. The most important decisions to be made are choosing the proper cleaning solution, cleaning at the right temperature for the correct amount of time, and choosing the right size and type of ultrasonic cleaner.
Depending on the type of cleaning requirement and the substrate that needs cleaning a detergent solution or similar aqueous medium can increase the cavitation. Lowering the surface tension of the liquid reduces the energy required to form the form the bubbles, and when combined with the cleaning property of the solution results in superior micro cleansing of the soiled surface.
The choice of the cleaning medium is critical. The nature of the substrate and contamination are the key factors in selecting the cleaning chemistry, which is typically aqueous or semi-aqueous.
Heat usually enhances and speeds up the cleaning process, and most detergent solutions are designed to work best at an elevated temperature. The best way to find the optimum temperature is to run tests. Choosing the right combination for a specific restoration cleaning situation can be challenging.
The number of cavitation bubbles increases proportionally to temperature increase. This happens up to about 140°F, beyond which cavitation begins to decline and stops completely when the liquid's boiling point is reached. However as the temperature and vapor pressure increase the cavitation energy decreases. Thus, each cleaning chemistry provides maximum cleaning efficacy at an optimum temperature setting.
As with the cleaning chemistry and its properties, the choice of frequency is also critical. The size of the cavitation bubble determines the amount of energy released at implosion. This is governed by the frequency of the ultrasonic generator. Higher frequencies generate smaller-sized bubbles.
A larger cavitation bubble releases more energy on implosion resulting in a more intense cleansing action. A smaller bubble has a gentler impact. As a general rule of thumb, high frequency is good for fine particles and cleaning of very small features on substrates while the lower frequency is suitable for heavy and coarse contaminants.
Frequency variation, modulation, or sweep prevents formation of standing waves in the tank. A fixed frequency can produce a harmonic vibration that damages delicate parts like eletronic components. When operating in sweep mode, the ultrasonic generator's frequency is modulated slightly above and below the central frequency. Until recently sweep ultrasonics were only available in industrial and high end professional cleaning systems.
Whether you are a Treasure Coast area property manager, commercial general contractor, or home owner, One Call will provide quality work, timely service, and reasonable pricing. We pride ourselves on the high standards we have established and maintained as a Treasure Coast area contractor. We will gladly provide references if you are considering us for your next damage restoration project.