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FREQUENTLY ASKED QUESTIONS

1. What is Ortech dry ice pellet blast cleaning?
It is a process in which dry ice (solid CO2) pellets are propelled at supersonic speed, to impact the surface that is to be cleaned or prepared. The pellets are accelerated by a stream of compressed air in a controlled manner through a blasting machine, just as with other traditional blasting systems (sand, bead, soda, solvent and other blasting). The unique feature of dry ice is its ability to vaporize upon impact leaving no secondary waste. Today, most applications are able to be cleaned by the use of standard shop air, in the 30-¬90 psi range.

2. How to store the dry ice pellets?
Dry ice pellets should be stored in an ruggedly built insulated container. The thicker the insulation, the slower will be the sublimation rate. Depending upon the atmospheric condition, the quality of the container and the insulation thickness, usual dry ice sublimation is approximately 2% to 8% per day.

3. What is dry ice and how dry ice pellets are prepared?
Solid CO2 is commonly referred to as Dry Ice. It is produced by allowing liquid CO2 to expand to atmospheric pressure which forms dry ice snow. This snow is then compressed and extruded through dies to form pellets and nuggets. Pellets are cylindrical in shape with a diameter of 3.0 mm and length varying from 8.0 to 16.0 mm. At atmospheric pressure, the temperature of dry ice is -78.5�C.

4. How does the Ortech dry ice blast cleaning process works?
Dry ice blast cleaning 3-step cleaning process: 1. Pellet Kinetic Energy: This effect triggers fracture in the layer of the contaminant. 2. Thermal Shock Effect: The rapid temperature difference between the pellets and the layers of the contaminant produces localized high shear stresses between the successive layers of the contaminant which results in speedy micro crack propagation leading to final bond failure at the surface of the substrate. 3. Sublimation (Micro-Explosion): The sublimation acts as micro-explosion that removes completely the layer of contaminant from the substrate. Important to note here that while removing a brittle contaminant the process literally pill off the contaminant from the surface and for removing a malleable or viscous coating the process flushes the contaminant from the surface.

5. How does Ortech dry ice blast cleaning differs from sandblasting process?
Sandblasting is a harsh cleaning technique since it scrapes /scratches / cuts / chisel the contaminant from the surface. Whereas Ortech dry ice blast cleaning is a aggressive but gentle cleaning technique that leaves no abrasive effect on the surface since it lifts the contaminant from the surface.

6. Why one should use dry ice pellet instead of a traditional blast media for cleaning?
The hardness of the dry ice pellets is only 2 Mohs, thus the cleaning is completely non-abrasive however traditional blast media, like sand, glass beads, plastic beads, walnut shell, etc are bound to leave an abrasive effect on the surface irrespective of their type, size, nature. Further dry ice pellet after impact sublimates and goes back to atmosphere without leaving any waste of its own, the only waste created is the contaminant itself, whereas all traditional blast media leaves secondary waste behind. Also during cleaning the intricate portion or interior parts the entrapment of the grit media in the voids is a major problem. However since dry ice sublimates on impact, the entrapment of the dry ice pellet is not an issue.

7. What is the size of dry ice pellets desired for dry ice blast cleaning applications?
By and large dry ice pellets with a diameter of 3 mm are used for majority of the cleaning applications. However for some specific applications, e.g. for very delicate surfaces, dry ice pellets with a diameter of 1.5 to 1.8 mm can also be used. If the same is not available then, another option is to use a pellet cutter which cuts the standard dry ice pellets into crystal form and reduces their impact on the surface.

8. Does the Ortech dry ice blast cleaning process useful for complicated cavities?
Yes, since dry ice vaporizes upon impact, the process can be definitely used for cleaning complicated cavities where conventional grit blast media may get trapped.

9. What happens to the dry ice once it strikes the surface?
It does the work of removal of the contaminant from the surface. Thereafter instantly sublimates and returns to the atmosphere as carbon dioxide (CO2) gas without leaving any secondary waste.

10. What happens to the contaminant?
If the contaminant is dry and hard then it will break into small parts/chips that can be swept away or vacuumed. However if it is a wet substance like grease or oil deposit then we have to take a systematic approach for cleaning like start at one end and guide the contaminant to the other end from where it can be removed.

11. Does the dry ice pellets or contaminates ricochet?
As dry ice pellets, upon impact sublimates and goes back to atmosphere as CO2 gas practically they do not ricochet. As for the contaminant, they are usually washed away by the stream of compressed air and thus do not come directly back into the blast gun vicinity. However safety glasses for eye protection is recommended at all times during the cleaning operation.

12. Does the dry ice pellets cool the substrate?
Generally no. This is because the Ortech dry ice blast cleaning process is very rapid and the dwell period is too short to cause any significant change in temperature of the substrate. However if the contaminant is too hard to remove in that case we will have to increase the dry ice usage rate and in that case the mass per targeted area will be more which will result in a marginal drop in temperature only.

13. Does the process or the dry ice pellets damage the substrate/surface that is to be prepared or clean?
Absolutely no. Because most of our application involves production/process equipments, tooling and components that are made of cast iron, stainless steel, mild steel, aluminium, and the various alloy metals. Also the damage can never occur since the contaminant that is to be removed from these surfaces has very less bonding threshold than the damage threshold. However, when removing contaminant from softer substrates like soft wood and some softer plastics and fabrics, there level of deposition, nature, etc. must be examined on a case-by-case basis and then and then only decision of cleaning must be taken.

14. Can the Ortech dry ice blast cleaning process be used to clean hot mold / surface online?
Yes certainly. The process cleans best when the surface is hot. Most contaminants have much weaker adhesive strength when they are in hot condition. Further the temperature change of the surface being cleaned is negligible compared with the mass of mold and the corresponding tensile stress will be well below the point of what most mold/surface will encounter during normal heat treatment. However with very thin molds where tolerances are critical, some testing may be required to determine if the drop in temperature would alter the structure of the mold.

15. Will the process create condensation?
The cleaning agent i.e. dry ice pellets does not produce any moisture or does not exists in liquid state at any point of time during the cleaning process. However the condensation of the moisture from the air surrounding the surface to be cleaned depends upon the dry ice usage rate, the dwell time and the local climatic conditions. Also the condensation occurs when the temperature of the substrate fall below the dew point temperature. This condition happens very rarely. When cleaning hot surfaces it is rare to have condensation because we seldom cool them below the dew point temperature. Even if condensation forms it can be dealt quite easily using appropriate methods.

16. What equipments shall I need for the cleaning applications?
The Ortech dry ice blast cleaning system will come completely with the dry ice blast and air hose, blast gun and nozzles best suited for the cleaning applications and user friendly manual to reference and train the staff. The other things needed for the operation of the Ortech dry ice blast cleaning system is the plant air, an electric power connection and the Ortech dry ice pellets.

17. How much air will be needed for effective cleaning?

The distinctive Ortech dry ice blast cleaning systems operates at a pressure range between 4 to 6 bars with a volume flow rate of 140 to 170 cfm for most of the applications. However your needs will depend on the applications. OES has wide variety of nozzles suitable for wide rage of flow rates and pressures.

18. Does one need an air dryer?
For dry ice blast cleaning applications the carrier fluid used is compressed air. This has to be dry to ensure free flow of the pellets till they make an impact on the contaminant. Ortech dry ice blast cleaning systems operates with maximum efficiency when the air is dry and majority of the plants are able to provide clean and dry air. However where there is any doubt about the quality of air then in that case it is always advisable to use chillers or dryers. Moreover one should always blow down in plant air lines before hooking them up to the dry ice blast cleaning unit. This will eliminate water and sediment that may be present and prevent these impurities from entering the equipment.

19. How much dry ice pellets are needed to clean effectively?
The amount of dry ice pellets needed to clean effectively can vary significantly depending on the blast cleaning equipments and the applications. The typical Ortech dry ice blast cleaning system consumes approximately 26 to 52 kg of dry ice pellets per hr.

20. Can one vary the dry ice pellet consumption rate?
Yes, one can easily vary and control the effective dry ice pellet consumption rate by simply rotating the feed control knob located on the control panel of the Ortech dry ice blast cleaning systems.

21. How portable are the Ortech dry ice blast cleaning systems?
Ortech dry ice blast cleaning machines being very compact and versatile one person can easily move any of the machines around the plant at ease without the aid any special equipment.

22. Is it all right to use Ortech dry ice blast cleaning process in an enclosed area?
Yes, but with proper ventilation. Because CO2 is 40% heavier than air, we must have exhaust vents at or near ground level when blasting in an enclosed area.

23. Is it okay to use Ortech dry ice blast cleaning outside?
Yes, the dry ice blast cleaning is safe to use in an open area because there the existing ventilation is sufficient to prevent undue CO2 buildup.

24. How much regular maintenance is required to keep the system in perfect condition?
Very modest. Ortech dry ice blast cleaning systems are designed, developed and manufactured in a way to provide a trouble-free use and service with least amount of maintenance. The systems are supplied with an operator manual which has in it the maintenance schedule for each unit. With routine maintenance, one can expect continuous service for many years.

25. What are the primary safety issues related with the use of dry ice blast cleaning systems?
Ortech dry ice blast cleaning systems are designed in such a way that the operator does not have the access to any moving parts without switching off the unit. This invariably protects them from the moving parts. Further the temperature of the dry ice is very low (- 78.50C) hence the operator must wear gloves when coming in contact with it. Likewise eye and ear protection should be worn at cleaning times to prevent from any untoward accidents. In addition to this the blasting gun should be pointed only on the work piece than at anyone to ensure safe cleaning.

26. Does the system or the cleaning process creates noise?
Yes. Noise is a function of air volume and air velocity. Within the nozzle, the stationary air is sheared by the high velocity air causing turbulence which creates noise. With proper hearing protection the operator can safely operate the system all day.

27. Does the process generate static electricity?
Yes. Any dry air process will generate static electricity and Ortech dry ice blast cleaning is no exception. If both the blasting system and the work piece that is to be cleaned is properly grounded, then there won�t be any static discharge problems.

28. Does the dry ice blast cleaning techniques replace the conventional cleaning methods like sandblasting / bead blasting / water blasting, etc.?
However consider that there is toll box containing different types of pliers viz. gripping plier, special purpose plier, adjustable pliers, cutting pliers, crimping pliers, rotational pliers, etc. Could each do the job of the other? Obviously no, thus the ideal toolbox would include each, because each has specific capabilities that it does better than any of the others. Like wise although Ortech dry ice blast cleaning has enormous advantages compared with the traditional cleaning methods we recommend this technique to those industries and organizations that are concerned predominantly with downtime, entrapment, waste disposal volume, quality of cleaning, abrasive effect, equipment life, toxicity, hazardousness, corrosively, conductivity, etc. and moreover employee�s health, safety and the environmental impact of the business.

29. What sort of contaminant can be removed effectively by Ortech dry ice blast cleaning?
Ortech dry ice blast cleaning remove contaminants such as oil, grease, adhesives, ink, dirt, dust, rust, carbon, soot, pulp, paint, cadmium/cardium deposits, tar, food particles, water lines, mold, cellulose, insulation, etc.

30. What cannot be removed?
Thick coatings of very hard material that have a strong bond with the underground, examples are baked-on enamel on cast iron, primers in car parts, silicate deposited on the blades of the steam turbine rotor and diaphragms blades etc. Likewise it is difficult to remove strong bonding contaminant from the base material that is too soft, examples soft wood, plastic, etc.

31. What are the industries where dry ice blast cleaning technique finds its applications?
The dry ice blast cleaning applications are as wide and diverse as industries itself. The subsequently mentioned industries are the ones where it predominantly finds its applications; airlines, automotive, casting, chemical, dairies, electrical, electronics, food, beverage, foundries, locomotive both diesel and electric, moulding, packaging, paper, printing, pharmaceutical, power generation, rubber, wood, etc.

32. How the Ortech dry ice blast cleaning system stands apart in terms of reliability than other systems in the market?
The Ortech dry ice blast cleaning system stands apart in terms of reliability than other systems in the market mainly because of the following distinct features. It is a dependable single hose system ensuring most aggressive, efficient and gentle cleaning. It has a very operator friendly and precise control panel having a safety instruction sheet with symbols and textual explanation that are self explanatory. It is compact, versatile, light, durable, reliable requiring very minimum maintenance because of specially and masterly designed components. It is provided with a blasting gun and a set of nozzles for substantiating the most perfect cleaning. The gun provided with our system is so scrupulously designed that by operating the controls on it the operator can control the systems electric and pneumatic operation. Convince yourself by requesting a demonstration. We will be happy to organize it for you.