Mold remediation case study using cold jet dry ice blasting to remove mold from difficult to clean areas
What is dry ice blasting?Dry ice blasting is a process in which dry ice rice is propelled at high velocities to impact and clean a surface. The particles are accelerated by compressed air, just as with other blasting systems. Today, most applications are able to use standard shop air, in the 80 - 100 psi range.
How does dry ice remove contaminants?
It depends on what you’re cleaning. If you’re removing a brittle contaminant such as paint, the process creates a compression tension wave between the coating and the substrate. This wave has enough energy to overcome the bonding strength and literally pop the coating off from the inside out. If you’re removing a malleable or viscous coating such as oil, grease, or wax, the cleaning action is a flushing process similar to high pressure water. When the particles hit, they compress and mushroom out, creating a high velocity snow flow that will actually flush the surface.
Sandblasting is similar to using an ice pick or chisel whereas dry ice blasting is similar to using a spatula. Sand will cut or chisel away the contaminant. Dry ice lifts the contaminant away the without damaging the surface being cleaned. Dry ice blasting works great for historical restoration as it does not damage the underlying surface.
What happens to the dry ice once it reaches the surface?
Dry ice sublimates and returns to the atmosphere as carbon dioxide (CO2 ) gas. CO2 is a naturally occurring element that constitutes less than 1% of our atmosphere.
What happens to the contaminant when dry ice impacts it?
People may think the contaminant disappears along with the dry ice, but it does not. All cleaning involves the relocation of dirt. When you mop a floor the dirt moves from the floor to the mop to the water in the bucket. With dry ice, the dirt moves from an undesirable area to an area where you can better deal with it. If it is a dry substance, it generally falls to the floor where it is swept away or vacuumed during normal maintenance. When cleaning mold with dry ice blasting the mold is removed from the surface and air filtration machines remove it from the air. Any settled spores get hepa vacuumed and wet wiped. If it is a wet substance like grease, you take a methodical approach similar to washing a driveway with your garden hose. You start at one end and guide the grease to the other end where it is vacuumed or squeegee up.
Does dry ice blasting damage the substrate you are cleaning?
Generally dry ice does not damage the surface, but it depends on the substrate. There is an energy threshold at what point disbonding will occur and a threshold at which damage will occur. When the disbonding threshold is lower than the damage threshold, you can clean. If the reverse is true, damage can occur. Most of our applications deal with production equipment (cast iron, tool steel, tool grade aluminum), so there is no damage. We do have success with softer substrates such as plastics, wiring, pure copper, and fabrics, but these must be examined on a case-by-case basis.
Can dry ice be used to clean hot online equipment?
The dry ice cleaning process cleans best when the surface is hot. Most contaminants have weaker adhesive strength when they are hot. In many applications, we may be able to clean three to five times faster hot than cold. In addition, because dry ice sublimates on impact, entrapment of the blasting media is not an issue. Grit entrapment is an important reason those who clean with sand, walnut shells, or other grit media cannot clean online.
How is dry ice made?
Dry ice is made from liquid carbon dioxide. Dry ice exists as a liquid only under high pressure. When dry ice drops to ambient pressure (the normal pressure that surrounds us), approximately half turns to gas and half turns to solid. The solid, usually in the form of fluffy snow, is then compressed to form dry ice blocks, pellets, rice, or nuggets.
How did the dry ice blasting technology originate?
Dry ice blasting originated in the 70’s when a coatings engineer was researching ways to strip paint off of aircraft. The technology did not become commercially available until it was introduced into the marketplace in 1987.
Can dry ice blasting be used to remove paint?
Yes, however, the removal rate is dependent on many factors including: the underlying surface profile of the substrate; the thickness of the coating; the adhesive bond strength of the coating; and the cohesive strength of the coating (generally a function of age). Paint removal rates can vary dramatically, from 300 square feet/hour down to 1 square foot/hour. Generally speaking, if you have concerns with contamination, toxic substances, waste disposal, or substrate damage, dry ice blasting should be considered as a cleaning option. Otherwise, grit blasting is probably a more efficient method for paint removal.
Can dry ice blasting be used to clean wood?
Dry ice blasting will raise the grain on the wood, leaving a finish similar to that of sandblasting. If you need a smooth wood finish, dry ice blasting is not the answer. The primary interest here has been in lead paint abatement. Most other removal methods create too much additional toxic waste. Because dry ice disappears as it strikes the surface, the only waste that must be disposed of is the paint itself.
Is it okay to dry ice blast in an enclosed area?
Yes, with proper ventilation. Because CO2 is 40% heavier than air, placement of exhaust vents at or near ground level is recommended when blasting in an enclosed area. In an open shop environment, existing ventilation is sufficient to prevent undue CO2 build-up.
Case Study - Mold Remediation
Clean Faster - Clean Better using dry ice
Cleaning faster means more time for more jobs. In the mold industry most people only
have mold removed professionally if it is affecting there health so more jobs means more
peoples health issues are resolved. It also means lower costs per project. Cleaning
better means more satisfied customers and inspectors; it means passing the clearance
test the first time which is what we want every time.
The black mold varieties (including Stachybotrys and Memoniella) are typically the most
difficult to remove, as they burrow deeper into the wood.
When using dry ice blasting methods we can effectively remove these types of mold.
In addition to mold remediation, we can also use our dry ice blast
systems for fire and historic restoration. Dry Ice Blasting is also used in lead paint
abatement, water and storm damage repair, as well as graffitti, adhesive and tar removal.
Benefits of using dry ice blasting as a solution to your mold concern
• Replaces the sanding and grinding process for mold removal.
• Reduces labor time and cost
– 10 day job to 3 days
– 6 workers to 2 workers
• Drastically reduces encapsulation use.
• Drastically reduces or eliminates biocide use.
• Provides for a complete clean
– Able to access tight and confined areas. We can clean attics and crawl spaces with
ease
– Able to clean between beams and sheathing and around nails.
– As close to 100% spore removal as you can get.
• We consistently receive lab reports with better than expected spore count removal rates. In fact, we have even experienced “zero” spore count from the lab with clearance tests using dry ice blasting.
• Safer for the operator and less physically taxing.
• Dry Ice Blasting provides a complete clean, otherwise unachievable with traditional methods.
What is Dry Ice Blasting
Dry ice blasting uses compressed air to accelerate frozen carbon dioxide (CO2) “dry ice” particles to a high velocity. A compressed air supply of a minimum of 50 scfm (1.4 m3/min) at 80 psi (5.5 bar) can be used. The dry ice particles sublimate to a gas uponimpact with the surface being cleaned. As they convert from a solid to a gas they expand to 800 times their size resulting in a mini-explosion that lifts the contaminate from the substrate.
Why Switch to Dry Ice Blasting?
It is a dry, non-abrasive, environmentally responsible process that is both effective and efficient:
• Eliminates secondary waste
• Cleaning can be done online and in-place
• It will not harm active electrical parts
• Will not contribute to mold growth
• Will not damage or alter most surfaces being
cleaned
• Will not affect mechanical components on or
surrounding the equipment being cleaned
• Eliminates the use of hazardous chemicals
• Reaches where manual cleaning cannot
• Cleans rapidly and effectively
• Reduces labor costs
• Reduces or eliminates equipment replacement
costs from damage due to
- Abrasion or
- Disassembly, transport and reassembly
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