Questions and Answers About CO2 Pellet Blasting

How Does CO2 Pellet Blast Accomplish Cleaning?

How Does the CO2 Pellet Blast Compare With Grit Blasting?

In What Kinds Of Applications Has CO2 Pellet Blast Proven Effective?

Does Dry Ice Blasting Cool the Base Material? Is This Desirable? Will It Damage the Base Material?

Since There Is No Grit Entrapment To Worry About With CO2 Pellets, Can I Clean My Tooling In The Machine Without Disassembly? What if The Tooling Is Hot?

I Have Some Channels and Tubes In My Equipment. Can CO2 Pellet Blast Handle Them?

What Kinds Of Applications Are Not So Effective For CO2 Pellet Blast?

How Long Can I CO2 Pellet Blast before the Equipment Freezes Up?

Is It Safe For the Workers To Be In A Confined Space While CO2 Pellet Blasting?

Q. How Does CO2 Pellet Blast Accomplish Cleaning?

A. The CO2 Pellet Blast is an ingenious method of cleaning. Here is how it works.

Small ice pellets are accelerated through one of a variety of cleaning nozzles, using compressed air variable from 50 to 250 psi.

When the pellets hit the surface to be cleaned, their kinetic energy causes them to penetrate to the base material, at which point they shatter, blasting fragments laterally in all directions, releasing the contaminant from the base material.

Instantaneously, the dry ice fragments sublime, i.e. directly turns from solid to gas. The expansion of the CO2 from solid to gas adds a lifting force contaminant.

The debris falls away and the CO2 gas returns harmlessly to the atmosphere.

Q. How Does the CO2 Pellet Blast Compare With Grit Blasting?

A. The comparison of CO2 Pellet Blast has several dimensions.

CO2 Pellet Blast is a direct substitute for grit blasting in applications where there is a need to protect the objects being cleaned from the kind of damage that grit can cause. For example, CO2 Pellet Blast is particularly useful when:

Maintaining dimensional stability is critical.
Possible degradation to the finish of a product is a concern.
Chance of grit entrapment jeopardizes operating machinery or electrical equipment.

Where the drawbacks of abrasive grit is not an issue, CO2 Pellet Blast may not be a direct substitute. Grit blasting equipment is generally less expensive than CO2 Pellet Blast, and for some applications grit blasting can perform the cleaning task faster.

In the comparison with grit blasting, several key cost benefits of CO2 Pellet Blast are sometimes overlooked. These benefits include:

No special preparation is required, e.g. masking, covering and/or relocating equipment.
CO2 pellets do not create a collection or disposal problem since they disappear on contact.
Safety is enhanced using CO2 Pellet Blast.

Q. In What Kinds Of Applications Has CO2 Pellet Blast Proven Effective?

A. There is a vast array of cleaning applications that CO2 Pellet Blast serves well. Here are just a few:

Production equipment normally dismantled and transported to special areas can be cleaned safely in place on the production floor, saving substantial downtime and other resources.
Industrial control panels, man­fans, and other electrically sensitive equipment now being cleaned by hand can be blasted safely with dry ice pellets, since CO2 is entirely nonconductive.
Continuous web process ­ such as paper, printing, and food processing benefit from in­place cleaning particularly well. Conveyors of all types are easily cleaned with CO2 Pellet Blast.
Carbon dioxide does not become radioactive, so CO2 Pellet Blast is a natural choice for nuclear decontamination. The only disposal required is for the debris. The CO2 disappears harmlessly back into the air.

Q. Does Dry Ice Blasting Cool the Base Material? Is This Desirable? Will It Damage the Base Material?

A. Cooling impacts cleaning and base materials in this manner:

Some cooling takes place in the base material, but the amount of cooling seldom exceeds 40°F below its initial temperature. The likelihood of damage due to cooling is remote.
For a few kinds of applications cooling makes a small contribution to the cleaning process, principally with those contaminants that break up more easily due to thermal shock, e.g. those with high moisture content or high freezing point. Most of the cleaning results from good velocity/kinetic energy, hard pellets, and the impact­flushing action described in the first question.

Q. Since There Is No Grit Entrapment To Worry About With CO2 Pellets, Can I Clean My Tooling In The Machine Without Disassembly? What if The Tooling Is Hot?

A. These questions address some important advantages of cryogenic cleaning.

Yes, as long as the cleaning residues do not cause a problem. One of the major benefits of dry ice blast cleaning derives from cleaning tooling while still in the machine; less downtime, dismantling, and reassembly.
Hot tooling is often easier to clean than cold. Certain contaminates do not adhere as tenaciously when heated, and sometimes there is a more positive effect from thermal shock to the contaminant. The tooling is not adversely affected.

Q. I Have Some Channels and Tubes In My Equipment. Can CO2 Pellet Blast Handle Them?

A. Many channels and tubes can be cleaned well with CO2 Pellet Blast but there are some limitations:

This is basically a line­of­sight cleaning method. The pellets have limited effect around corners.
In cleaning deep cavities, back pressure is created that counteracts the blast effect and reduces the speed of the pellets.
Difficult configurations for cleaning include deep, narrow channels, very small tubes, tubes with closed ends or tubes with bends.

Q. What Kinds Of Applications Are Not So Effective For CO2 Pellet Blast?

A. The effectiveness of CO2 Pellet Blast may be limited by some of these factors.

Base materials and contaminates are multi­varied. Hardness viscosity, grain, toughness and other such measures combine to make a wide range of cleaning situations.
Every substrate has a threshold for absorbing energy (Et). If the kinetic energy of the pellets exceeds that threshold, damage will occur.
Also, every containment or coating exhibits a minimum kinetic energy required to shatter, splinter or be penetrated (Ep).
In similar fashion, the adhesive bond between the coating and the base material will not fail or be released until a certain minimum shearing force is applied (Es).
CO2 Pellet Blast is effective in almost any application where Et is clearly higher than either Ep or Es. This is the "window of effective cleaning".
Wood and some softer plastics could be damaged. Brittle substances like thin untempered glass, could shatter.
Some coatings are very hard and some bond very tenaciously. In these cases, CO2 Blasting technology may not be the best cleaning method. An example might be removal of baked­on enamel from cast iron.

Q. How Long Can I CO2 Pellet Blast before the Equipment Freezes Up?

A. CO2 Pellet Blasting can be continuously performed without any shutdown from equipment freezing.

Q. Is It Safe For the Workers To Be In A Confined Space While CO2 Pellet Blasting?

A. Yes, it is safe for workers to be in a confined space while CO2 Pellet Blasting.

CO2 by itself should prove not to be an added danger. Most of the problems in confined spaces are from the contaminate being removed. It is suggested to:

Provide adequate ventilation, monitor the air quality and follow confined space entry safe practices and procedures.

TechniClean P.O. Box 9337 Yakima, WA 98909 (509) 877­7066	Back	Email TechniClean