773726

Dry ice blasting: non-toxic, non-abrasive cleaning

Your introduction to dry ice blasting

 

Dry ice blasting is an innovative, non-toxic, non-abrasive cleaning method that produces zero secondary waste. Secondary waste includes sand, glass, dirty water, dirty cloths, chemical containers, and any other waste product left over after other cleaning methods. 

Dry ice blasting is an alternative to sand, bead and soda blasting. Carbon dioxide (CO2) pellets replace traditional blasting materials such as steam, waste and chemicals.  These small rice-sized pellets are blasted with compressed air at the dirty surface. The extremely low temperature of the dry ice (-78°C) kills any bacteria and freezes the soil, which becomes brittle and flakes off.  The pellets sublimate on impact, leaving only the dislodged soil to sweep up off the floor.  Being non-abrasive, dry ice leaves the original surface in perfect condition. 

This method can also be called dry ice cleaning, CO2 blasting or cryogenic cleaning. 

 

On this page, you can learn:

 
 

 

What are the uses of dry ice blasting and what problems can it solve?

Here at Presco Environmental, the main way we use dry ice blasting is to clean surfaces.  This method can range from very aggressive to delicate.  By adjusting the compressed air pressure, we can clean delicate surfaces, like electrical components, sensors, flashings glass and soft alloys.  At the other extreme, we can also remove very heavy build-up, such as tar, melted plastic, baked-on milk powder or UVC coating.  Dry ice blasting is often a solution to jobs we cannot do any other way. 

 

Presco Environmental Operations Manager, Daniel, using dry ice blasting to clean in place
Presco Environmental Operations Manager, Daniel, using dry ice blasting to clean in place

 

This method is ideal for situations where there is:

  • a very tough build ups, such as baked-on product
  • electrical or sensitive componentry
  • too much downtime in cleaning
  • a dry environment, such a milk powder drier
  • requirements for no secondary waste, such as water or sand.

 

What are some examples of dry ice blasting outcomes?

 

Before & After

 

 


Coldjet case studies

 

Waffle factory brings new life back to old molds without water or chemical

> Learn more

A bakery and foodservice factory cuts costs and equipment
downtime while increasing productivity by 80%

> Learn more

 

Chocolate facility reduces cleaning time by 60%,
and reduces maintenance costs and downtime

> Learn more

Wooden brewing vessels thoroughly cleaned without affecting flavor

> Learn more

Bakery uses dry ice blasting to reduce cleaning labor from 25 to 2 people

> Learn more


 

What are the benefits?

Dry ice blasting has many benefits that make it an excellent cleaning method for the food industry.  The top 10 include:

  1. No secondary waste: clean without clean-up
  2. Zero water: dry cleaning
  3. Non-toxic: completely clean, chemical-free
  4. Sustainability: is there a more sustainable cleaning method than this?
  5. Non-Conductive
  6. Sanitise as you clean
  7. Deep clean-in-place: reduce your plant downtime, increase your productivity
  8. You’d blast my baby?! Non-abrasive
  9. No residue left behind
  10. Reduced costs 
  11. [Bonus] Odour-free cleaning

Read more about the benefits here.

 

What are the alternatives?

 

You could buy your own machine.

This is an intelligent idea if you plan to do a routine small job, such as a quick clean at the end of every shift.  For a job like this, it is unlikely bringing in a contractor will be cost-effective. 

 

You could use a different chemical-free method of cleaning.

Steam cleaning and pressure washing are also chemical-free methods of cleaning. 

Dry or wet steam cleaning is good for cleaning oily or waxy surfaces.  This method of cleaning generally requires 3 phase power, so ensure this available before planning to start.

Pressure washing is the cheapest option.  It is perfect for situations where the soil will easily remove and water is no issue.  Pressure washing generally requires a drain for the water to wash down. 

 

You could use abrasive blasting.

Sand blasting, soda blasting, and bead blasting are all examples of abrasive cleaning.  They are very effective in cleaning and will remove everything including paint and rust.  Abrasive blasting cleans back to bare metal but it creates a lot of mess and is extremely harsh on sensitive equipment, such as seals or wiring.

 

You could use chemical cleaning.

To remove the kind of build-ups that dry ice blasting is used for, you would need very strong, harsh and toxic chemicals.  This process often involves a lot of soaking, water and downtime for your plant.

Often there are solutions that are cheaper by the hour, but they will nearly always take a lot longer than dry ice blasting would for the same job. 

 

Dry ice blasting compared to alternative cleaning methods

dry ice blasting compared to alternatives cleaning methods

Information retrieved from coldjet.com

 

Frequently asked questions

 

What is dry ice?

Dry ice is the solid form of recycled carbon dioxide (CO2) which is a natural part of the atmosphere.  At atmospheric pressure, dry ice is -78°C.  It is odour-free, non-toxic and incombustible, 

When dry ice melts, it goes through a sublimation process. Sublimation is the transformation directly from solid to gas, without first becoming liquid.  Therefore, dry ice does not produces liquid where standard ice produces water.  When dry ice melts, it merely turns into a gas and disappears.  Hence the name – dry ice. 

 

Does dry ice blasting create dangerous amounts of CO2 in the air?

No.  Your people can keep working while your plant is being dry ice blasted.

Thankfully, it changes the CO₂ level in the air very minimally.  This is why musicians can keep singing while dry ice smoke covers their stage.  It is also why, with standard mechanical ventilation or natural airflow, dry ice technicians and other room occupants are completely safe.  However, some vigilant technicians will still have gas detectors on them as an additional safety precaution.

 

Can dry ice blasting cause an explosion?

This is only a possibility in high dust level environments. 

In a very powdery environment, like sawdust or milk powder, explosions are a hazard.  These are a possibility when static energy builds up, then a spark is created, causing ignition.  If this is a problem, our equipment has earth grounding leads and technicians can use non-conductive lances to ensure no discharge is caused when two metal surfaces touch.

 

Does it damage the surface it is cleaning? 

No. 

In untrained hands, dry ice blasting can cause problems with sensitive surfaces. Despite that, it stands out head and shoulders above all other blasting methods as being non-abrasive.

In trained hands, it can be so gentle it will not damage bearings, seals, nozzles, labels, glass, plastics or electrical components.

To learn more about non-abrasive cleaning read Matthew’s article: You’d Blast My Baby?! Non-Abrasive: 10 Key Benefits Of Dry Ice Blasting – #8

 

Does dry ice blasting cause condensation? 

Yes, it can do.  It is important to have the right air controls and the right gear.  But don’t you worry about that – we take care of all the fans, heaters and dehumidifiers your job will need.

   

Will dry ice blasting work for rust removal?

Dry ice can remove rust.  Read more about its effectiveness in this article from Blackwell’s Inc: Can dry ice blasting remove rust?

 

Will dry ice blasting remove paint?

Yes, but it is very slow.  We would only recommend it for situations where no other option will work. 

For example, we had a customer who managed an enzyme factory.  He needed to remove paint from the ceiling, but could not have sand or water falling down into his product.  Dry ice blasting was an excellent solution for this problem. 

Have further questions?  This very informative article “Is dry ice blasting dangerous” answers a further three questions:

  1. Do I need to use a breathing apparatus when dry ice blasting?
  2. Does cleaning with CO2 contribute to climate change?
  3. Extreme cold and ricocheting – is it dangerous to people?

 

How much does dry ice blasting cost?

It often costs between $3200-$6000 per day, depending on where in the country your site is, and other inputs.  Our general manager and senior industrial hygiene advisor, Matthew Prestidge, broke down the cost of dry ice blasting in this article: How Much Does Dry Ice Blasting Cost?  

 

What are the limitations of dry ice blasting? Where does it not work?

 

  • Noise is the most hazardous part. Compressed air passes through a narrow orifice in the gun, creating a very loud rushing noise.  Grade 5 ear protection is required.
  • Dry ice blasting cannot clean wet grease; it will spray everywhere. To avoid ricocheting grease onto other areas, use a degreaser or wipe away the wet grease before blasting.
  • It is not effective at preparing a surface for repainting. To be painted, steel has to have a key.  Sandblasting scuffs up the surface, creating keys for the paint to stick to.  Dry ice is not abrasive so cannot cut these keys into any surface.
  • It is very slow at paint removal. You can read more about this above in the frequently asked questions section.

 

The science behind how it works

 

(All information in this section is retrieved from Coldjet.)

Dry ice blasting combines three primary factors to remove contaminants:

  • Pellet Kinetic Energy
  • Thermal Shock Effect
  • Thermal Kinetic Effect

 

Pellet Kinetic Energy

Dry ice is accelerated by compressed air through a nozzle at supersonic speeds. When the dry ice collides with the substrate being cleaned it creates a kinetic effect. This effect has the largest contribution to the cleaning process when substrates are at ambient temperatures or below.

Even at high impact velocities and direct head-on impact angles, the kinetic effect of solid CO2 pellets is minimal when compared to other media (grit, sand, PMB). This is due to the relative softness of a solid CO2 particle (1.5 – 2 on the Mohs Scale of Hardness), which is not as dense and hard as other blasting media. Also, the pellet changes phase from a solid to a gas, almost instantaneously, upon impact. Very little impact energy is transferred into the coating or substrate, so the dry ice cleaning process is considered to be non-abrasive.

 

Thermal Shock Effect

The temperature (-109°F / -78.9°C) of the dry ice causes thermodynamic shock, which causes the contaminant to embrittle and shrink. The resulting micro-cracking helps break the bond between the surface and the contaminant.  The instantaneous sublimation (phase change from solid to gas) of dry ice upon impact absorbs maximum heat from the very thin top layer of the surface contaminant.  Maximum heat is absorbed due to latent heat of sublimation.  The very rapid transfer of heat into the dry ice from the coating top layer creates an extremely large temperature differential between successive micro-layers within the contaminant. This sharp thermal gradient produces localized high shear stresses between the micro-layers. The shear stresses produced are also dependent upon the contaminant’s thermal conductivity and thermal coefficient of expansion / contraction, as well as the thermal mass of the underlying substrate. The high shear produced over a very brief period of time causes rapid micro-cracking between the layers leading to the failure of the bond between the contaminant and surface of the substrate.

 

Thermal Kinetic Effect

Upon impact, the combined impact energy dissipation and extremely rapid heat transfer between the pellet and the surface causes the dry ice particles to sublimate, or expand instantly, and return to the natural gas state. During this phase transition from solid to gas, the volume of dry ice expands up to 800 times in a few milliseconds and lifts the contaminant off of the substrate. This is effectively a “micro-explosion” at the point of contact. 

The “micro-explosion” aids in the lifting of thermally-fractured coating particles from the substrate. This is because of the dry ice particle’s lack of rebound energy, which tends to distribute its mass along the surface during the impact. The CO2 gas expands outward along the surface and its resulting “explosion shock front” effectively provides an area of high pressure focused between the surface and the thermally fractured contaminant particles. This results in a very efficient lifting force to carry the particles away from the surface.

 

Other useful resources: 

 


 

Matthew Prestidge, General Manager

Got a question?

Contact our senior Industrial Hygiene advisor, Matthew Prestidge, at matthew@presco.co.nz

 

BOOK A JOB

Enquire or Book a job
0800 773 726
06 278 0712
PO Box 530, Hawera, 4610
© Presco Group Ltd
Designed and developed by Strategy Collective