FAQ
ASCOJET - Dry Ice Blasting
Below are listed some of the most common questions in the connection with our ASCOJET Dry Ice Blasting Technology. Should you have any other questions, please do not hesitate to contact us.
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What is CO2?
Carbon dioxide or CO2 is an odourless, inert gas approximately 1½ times heavier than air and 0.03 % is normally present in the earth's atmosphere. It is also found in great quantities in volcanoes, earth cracks, other sources and in the metabolism of plants, animals, and human beings. Commercially, CO2 can be recovered as a by-product from various chemical industries and is usually stored in a tank after recovery. Carbon dioxide can exist in three forms:
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- in gaseous form |
(for the beverage and food industries) |
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- in liquid form |
(in a storage tank under pressure) |
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- in solid form |
(called dry ice, for cooling, blasting etc.) |
What is dry ice?
Dry ice is the solid form of CO2. Dry ice is produced from liquid carbon dioxide. Inside a pelletizer, the liquid carbon dioxide is expanded under controlled conditions to form dry ice snow. This snow is then pressed through an extruder plate into round, hard pellets (elongated grains with a diameter of 3 mm or 1.7 mm according to the used extruder plate) for dry ice blasting purposes or into dry ice slices/blocks for cooling purposes. Dry ice has a temperature of approx. -79 °C. For further information please see also under ASCOJET Dry Ice Blasting Technology.
How does dry ice clean?
The ASCOJET Dry Ice Blasting machine accelerates the dry ice pellets to a speed of approx. 300 m/s. The pellets hit the object to be cleaned. The surface is shock-frozen in a fraction of a second. Due to the sudden thermo shock generated on the surface to be cleaned, the coating/dirt contracts, becomes brittle and cracks. Due to the cracking of the surface, the pellets can reach under the dirt and remove it. The additional kinetic energy removes the coating/dirt from the surface.
Immediately after impact, the pellet sublimates and goes back to atmosphere as a pure gas (CO2) without leaving any moisture behind. The only thing left is the coating/dirt removed from the surface. Since the hardness of the pellets is only approx. 2 Mohs, the cleaning is virtually non-abrasive, and the surface quality is maintained. For further information please see also under ASCOJET Dry Ice Blasting Technology.
Where can ASCOJET dry ice blasting be applied?
Dry ice blasting basically removes all material which reacts strongly to differences in temperature. Paint, varnish, adhesive, oil, wax, residues in bakeries, bitumen, synthetic residues and foams (e.g. PU) etc. are removed easily without damaging or altering the surface. Even delicate parts like switch boards and other electric components can be cleaned gently. As ASCOJET dry ice basting is virtually non-abrasive, this technology is highly recommended for gentle and effective cleaning of moulds of any type and material in all industries (e.g. ingot moulds, core boxes, injection moulds, high pressure die casting moulds, moulds for PU-products, waffle irons etc.). Click here to find a list and pictures of possible applications.
What are the advantages over other cleaning methods?
Gentle
In comparison to traditional blasting methods with sand or glass beads ASCOJET Dry Ice Blasting does not damage or alter the cleaned surfaces and is virtually non-abrasive.
No dismantling
ASCOJET Dry Ice Blasting can be applied directly on the moulds/plants without disassembling them. This saves valuable time and allows virtually continuous production. Even hot moulds can be cleaned on-line with minimal effect on mould temperature. This way ASCOJET Dry Ice Blasting can easily be integrated in the daily working process and supports, with little expenditure, quality assurance and process reliability.
Dry
ASCOJET Dry Ice Blasting is a dry cleaning method. Therefore even delicate parts like switch boards and other electric components can be cleaned gently.
No residual blasting media
ASCOJET Dry Ice Blasting leaves no residual blasting media behind because the dry ice pellets sublimate immediately after impact on the surface. Therefore time and costs associated with disposal of blasting media are eliminated.
Ecologically friendly
ASCOJET Dry Ice Blasting is ecologically friendly. As mentioned no residual blasting media has to be disposed of. In addition, no solvents or chemicals are needed.
CO2 is gained as a by-product of other production processes (for example from the production of ammonia or from combustion processes). In all industrial countries CO2 is not produced separately and the combustion of fossil fuels in order to produce CO2 only has disappeared completely.
What is the temperature of dry ice?
The temperature of dry ice is approx. -79°C
Does dry ice blasting damage or alter the base material?
No, dry ice blasting is a gentle cleaning method and does not damage or alter the surface. For further information please see also under ASCOJET Dry Ice Blasting Technology.
Can dry ice cleaning be applied on hot surfaces? Does it cool down the surfaces (e.g. ingot moulds)?
Yes, dry ice blasting can be applied on hot surfaces. Due to the big difference in temperature, this cleaning method can be even more effective when the surface to be cleaned is hot. Even hot moulds such as ingot moulds in foundries can be cleaned online.
Due to the very high cleaning performance, ASCOJET Dry Ice Blasting has only a minimum effect on mould temperature allowing virtually continuous production.
Can I apply dry ice blasting on electric components?
Yes you can. ASCOJET Dry Ice Blasting is a dry cleaning method. Therefore even delicate parts like switch boards and other electric components can be cleaned gently. If you are not sure whether such an application is safe, please contact our specialists.
Is dry ice blasting ecologically friendly?
Yes it is, for several reasons: CO2 is gained as a by-product of other production processes (for example from the production of ammonia or from combustion processes). In most industrial countries CO2 is not produced separately and the combustion of fossil fuels to produce CO2 only has virtually disappeared. No solvents or chemicals are needed at all. After cleaning there is no blasting media left which has to be disposed of.
Is CO2 toxic?
No, CO2 is not toxic. The only danger of suffocation in small closed rooms can easily be eliminated with adequate fresh air suppy and a CO2 gas detector which supervises the CO2 content in the air. As dry ice is -79°C, safety gloves should be worn.
Is it recommended to use dry ice blasting in closed areas? Are there any risks?
Yes it is. However, wherever CO2 or dry ice is used in closed areas, high CO2 concentrations can be reached, especially in small rooms or basements where no fresh air is supplied. This leads to the danger of suffocation. In this case we recommend using a CO2 gas detector to protect the personnel by giving a signal when the CO2 concentration becomes too high. As a provider of complete solutions, we will also to be pleased to advise a full safety concept for you. Please contact us if you are not sure if dry ice blasting needs any safety measures in your facilities and with all your other questions regarding safety aspects.
Can I apply dry ice blasting outside?
Yes you can. However, please be aware that when blasting outside and using a mobile compressor, the correct compressed air for the required quality of blasting air becomes even more important.
How do I store dry ice?
Dry ice should be stored in special insulated containers to keep sublimation loss to a minimum. This way it can be stored for several days. However, please be aware that the fresher the dry ice, the better and faster are the cleaning results. In-house dry ice production therefore increases quality and flexibility in the daily working process and reduces costs remarkably.
What pellet size do I need for dry ice blasting purposes?
Standardly pellets with a diameter of 3 mm are used. For some applications, e.g. for very delicate surfaces, pellets with a diameter of 1.7 mm can also be used. Another option is to use a pellet cutter which cuts the dry ice pellets and reduces their impact on the surface.
Where can I purchase dry ice pellets?
We will be pleased to be your dry ice supplier in Switzerland, Germany, Austria or New Zealand. For other countries please contact us and we will help you to find your local dry ice supplier. However, please be aware that having a dry ice production of your own gives you much more flexibility and independence in the daily working process and leads to remarkable cost savings.
How is dry ice made?
Dry ice is produced from liquid carbon dioxide. Inside a dry ice pelletizer, the liquid carbon dioxide is expanded under controlled conditions to form dry ice snow. This snow is then pressed through an extruder plate into round, hard pellets for dry ice blasting purposes or into dry ice slices/blocks for cooling purposes.
Can I produce dry ice pellets myself?
Of course. With an ASCO Dry Ice Pelletizer you will always have freshly produced dry ice at your disposal and a maximum of flexibility and quality in the daily working process. Please contact us for more advice.
What are the advantages of in-house dry ice production?
Better and faster cleaning results
The fresher the dry ice, the better the cleaning results. With dry ice stored for several days the cleaning time can take twice as long or longer than cleaning with freshly produced dry ice.
Less dry ice use
As the cleaning results are much better with freshly produced dry ice than with dry ice stored for several days, the dry ice use is reduced remarkably. As you can produce your dry ice on demand and just in time, you do not have to store it for several days. This way the loss due to sublimation is kept to a minimum. For these reasons, in-house dry ice production reduces your dry ice use by up to 50%.
More flexibility
As you can produce your dry ice whenever you need it, you can also clean whenever you want and you do not have to wait for dry ice delivery. This way the cleaning easily can be integrated into the daily working process and be planned as fixed cycle times.
Shorter production downtime
As the freshly produced dry ice ensures faster cleaning results, your production stoppages are also shortened.
Less logistical expenditure
With in-house dry ice production you do not have to worry about where and when to purchase your dry ice, what time it will be delivered and how long you have to store it. You can produce it on demand and just in time.
All these benefits lead to more flexibility and quality in the daily working process and reduce costs and increase productivity.
When does in-house dry ice production pay?
In-house dry ice production pays if you need several hundred kg dry ice per week because of all the mentioned advantages (see question above). Please contact us and we will help you to find your optimum dry ice solution.
Where can I purchase CO2?
We will be pleased to be your CO2 supplier or to find the best CO2 solution for you. Please contact us for more advice.
What is the conversion rate from liquid CO2 to dry ice? Can the lost CO2 be recovered?
When dry ice is produced, the conversion rate from liquid CO2 is approx. 40-45 %. With a CO2 recovery system , however, most of the otherwise lost CO2 can be recovered to give a final conversion rate of up to approx. 90-95 %.
How does dry ice pellet blasting compare with CO2 snow blasting?
CO2 snow blasting is not actually in competition with dry ice pellet blasting but is a complementary cleaning method. The reason is that the cleaning performance is much lower and you have to work with high air pressures. CO2 snow blasting can then be brought into action if you have to clean very delicate components or if dry ice pellet blasting produces a large surplus of performance. However, our experience shows that most customers prefer the more efficient cleaning method, i.e. dry ice pellet blasting, because time saving is one of the most important criteria when choosing a cleaning method. As CO2 snow blasting does not cover all applications, it is mainly used by service companies as a complementary cleaning method to dry ice pellet blasting.
The users of pellet blasting have more flexibility as they can work with low air pressures or with a pellet cutter when cleaning delicate surfaces. The high pressures needed for snow blasting often causes problems as such high pressures are not available in all industries and because high pressures produce a high noise level.
Is there any blasting media left after cleaning?
No. Immediately after impact, the pellets sublimate and go back to atmosphere as a pure gas (CO2) without leaving any moisture behind. The only thing left is the coating/dirt removed from the surface. Costs and time associated with disposal of blasting media are therefore eliminated.
What hose extensions are possible with an ASCOJET dry ice blasting machine (vertical and horizontal)?
Depending on the ASCOJET machine type, hose extensions up to 75 m (horizontal) respectively 35 m (vertical) are possible. Such hose extensions are only possible with a double hose system using two positive air pressures. Blasting at such heights would not be possible with other hose systems without a major loss of performance.
What is the difference between a single hose and a double hose system? Which system does ASCO use?
The advantage of a single hose system is the easy handling. The dry ice pellets are transported and accelerated with high air pressure in one hose. The disadvantage is that the dry ice and high air pressure come together very early. The pellets break on their way to the gun causing lower cleaning performance. To compensate for this lower performance more dry ice used.
A double hose system consists of one hose with the air pressure for the acceleration and one hose for the dry ice transportation. This way, the pellets are transported gently with low air pressure and the acceleration only happens in the gun. The result is a higher pellets quality which means better cleaning performance and less dry ice consumption and therefore cost-effective cleaning. This system gives high cleaning performance at low air pressures and with less noise than with high air pressures.
ASCO has two dry ice blasting machines with a single hose system (ASCOJET 901, ASCOJET 1701) and two with a double hose system (ASCOJET 2001RX, ASCOJET 2001CS). All are driven electrically. In comparison to pneumatic motors, electric motors are more powerful and have fewer problems due to freezing. ASCO's double hose system works with two positive air pressures and is not comparable with the venturi system, which works with vacuum and is the lowest-powered system.
Are the ASCOJET Dry Ice Blasting Machines easy to move?
Yes. All ASCOJET dry ice blasting machines are very easy to move, compact and mounted on four wheels.
How loud is this cleaning technology?
According to machine model and used air pressure ASCOJET dry ice blasting machines have a noise level of approx 80-110 dBA. Therefore it is necessary to wear hearing protection when blasting. In this connection ASCO also offers special projects like noise control booths.
How much maintenance is required for the ASCOJET dry ice blasting machines?
Very little. ASCOJET dry ice blasting machines are designed so that maintenance needed is kept to a minimum. Most of the maintenance as well as trouble shooting can be done by the customer using the supplied manual or if needed with help of our after sales support by phone. Our dry ice blasting machines are very robust and designed for various industrial users and cleaning companies where time saving is very important, i.e. also time for maintenance or trouble shooting is kept to a minimum.
Do I need any special clothes when dry ice blasting?
Dry ice is a very cold material (-79 °C): Therefore industrial protective safety gloves and shoes should be worn. Eyes should be protected by proper eye protection from flying particles. High air pressures also produce a high noise level. So hearing protection is necessary.
What equipment will I need for my cleaning operation?
Our dry ice blasting machines all cover a wide field of applications. However, please contact us and we will help you choosing the right machine for your specific applications and the corresponding accessories to give your the best blasting system for your purposes.
What are the necessary blasting air conditions?
Blasting air should be dry and free from contaminants like oil, dust or other foreign particles to avoid malfunctioning valves and premature wear, and a separate air preparation plant is recommended. ASCO’s target is always to ensure best possible cleaning results with the air conditions generally given in the corresponding industrial branches. Depending on your application the needed air pressure varies between 0 and 16 bar with an air volume between 2 and 10 m3. Please contact us and ask our specialists who will be pleased to give you advice.
How much dry ice will I need?
From experience there is an average dry ice need of 40-60 kg/hour. Cost and time savings can be made by varying the dry ice consumption according to the specific applications. Please do not hesitate to contact our specialists and they will advise you in this respect. However, there are many aspects which are much more important for efficient and cost saving cleaning like a powerful blasting unit or freshly produced dry ice which provides a up to 50 % higher performance than dry ice stored for several days. Having in-house dry ice production will significantly increase quality and flexibility and reduce costs.
