According to Cold Jet, in the fire restoration industry, dry ice blasting freezes out the cleaning competition when removing soot, charring, and smoke damage is the task at hand.
Dry ice blasting allows the contract cleaner to expand his business by decreasing project costs and increasing cleaning efficiency and speed.
Dry ice blasting can reduce cleaning time by up to 70%, labour costs by up to 90%, and total project costs by up to 85% in the fire restoration industry.
The removal rate of fire damage from wood using dry ice blasting is about 7-10 sq ft per minute. An example of a fire restoration project would be completing a 2000 sq ft area in 3 days with 2 workers.
Only 1.5 days are spent blasting, while the remainder of the time is set-up and tear down for the project. This estimate also assumes the operator is not blasting 100% of the time during an 8 hour shift.
Dry ice blasting helps with odor elimination, while sanding and grinding does not. The surface that the fire damage is being removed from has an effect on the removal rate. For example, painted metal is slightly slower than wood removal, while painted brick is faster.
When comparing dry ice blasting to soda blasting, much of the savings come from reducing labour costs as well. With dry ice blasting there is no additional secondary waste to clean up as there is with soda blasting, which lengthens project time in the latter case.
Also, the restoration contractor is saving about $100 by using dry ice blasting versus soda blasting because less media is used.
How dry ice blasting works:
Dry ice blasting uses compressed air to accelerate solid 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 transform into a gas upon impact 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 contaminant from the substrate.
Since the dry ice becomes a gas, there is no secondary waste left behind to clean up.
Benefits of dry ice blasting:
Dry ice blasting is a dry, non-abrasive, environmentally responsible process that is both effective and efficient. There is no secondary waste created by the dry ice particles.
It is also non-toxic, non-corrosive, and non-flammable. It is safer for the operator, as they are not exposed to grit materials or harmful chemicals.
While dry ice blasting is only line-of-sight cleaning, it can get into hard to access corners and between beams. As a quick and effective cleaning method, it results in increased productivity and reduced labor costs.
Dry ice blasting can be either an aggressive or gentle cleaning method depending on the machine, nozzle, pellet size and type, and air pressure, which allows it to be used in various applications.
Since the dry ice particles convert to a gas upon impact and expand the contaminate is lifted from the substrate without damaging the substrate.
Some of the applications that fire restoration contractors also use their dry ice blasting systems for are mould remediation, historic restoration, and general building maintenance.
The technology of dry ice blasting:
In the single hose blasting system, which is ideal for the restoration industry, there is one hose leading from the hopper to the applicator and a feeder system that feeds the dry ice particles and compressed air into that hose.
The dry ice particles are accelerated by the compressed air stream the entire length of the hose, dramatically increasing their kinetic energy and therefore the aggressiveness of the clean.
The single-hose system is ideal because it gives the user the option of a longer hose, which allows further travel without moving the machine and without (or with little – depending on the length of the hose) reduction in blast aggression.
System aggression is ideal for removing heavier build-up or for blasting at a vertical, where the machine is situated at a lower level than where the blasting is taking place.
The dual-hose venturi system has lower blast aggression and does not allow for vertical blasting since it relies on a vacuum effect to blast the dry ice particles and air from different hoses.
Because the hose length is longer, thicker build-up can be removed, and vertical blasting is possible, the single-hose system is perfect for fire restoration projects.
There are also notable distinctions between single-hose and dual-hose nozzles.
The allowable diameter of venturi nozzles is limited by the lower efficiency and impact velocity created by pulling particles into nozzle by suction. Single-hose nozzles can be more varied due to the higher speed of the blast stream.
There are also so called convergent-divergent nozzles that are engineered to attain maximum pellet velocity by further optimising the transfer of energy from the compressed air to the pellets.
Pellets vs. block ice:
The dry ice media used for blasting comes in two forms: pellets or blocks.
The standard pellet size for blasting is 3 mm (1/8”) and they often allow for a more aggressive clean as the particles blasted tend to be larger and more irregularly sized.
Shaved block ice produces much finer and more consistently sized particles allowing for more delicate surfaces to be cleaned without damage.
Dry ice pellets have a larger mass whereas shaved ice has more kinetic energy.
So when would each type of blast material be used?
The smaller shaved particles have an advantage when removing most paints or when cleaning equipment with intricate geometries or tiny openings such as microvents or screens.
Pellets are more suitable when removing thick contaminants since the larger mass behind each individual pellet is better able to penetrate the contaminant and create the shockwave necessary to disbond it.
Shaved ice would be better used in cleaning delicate equipment such as semiconductors, while pellets would be the most effective way to clean printing presses and packaging equipment, for example.
In the fire restoration industry, blasting with pellets is ideal because it is able to remove the built-up soot and fire damage.
Dry ice blasting FAQ’s:
- How do I get dry ice?
- Dry ice producers have local distributors that produce both pellets and block dry ice.
- How much does it cost?
- Dry ice generally costs around $0.20/lb with contract and about $0.30/lb without.
- How do I need to store it?
- Dry ice is not a stockable media. It is typically delivered in 500 lb (226.8 kg) fully insulated, sealed totes that remain fresh 5-7 days while sealed. Once opened the dry ice should be used within 3 days for best blast performance.
- What are the safety concerns?
Dry ice should be handled with industrial gloves (with its low temperature media) and used in a well ventilated area as CO2 displaces oxygen. Typical plant ventilation systems easily meet these safety requirements.
Dry ice blasting is the new, fast and efficient way to do fire restoration. The back-breaking work from sanding and scraping is wiped out and the hours of secondary waste clean-up are eliminated.