Dry Ice Blasting - Aeon Green SubSurface

Dry Ice Blasting

Information Document

Aeon Green Limited 2 Dry Ice Blasting

Introducing Us

Aeon Green Subsurface is a privately owned UK based SME managed by its owners and is

part of the Aeon Green Group of Companies.

Initially set up in 2010 to provide Drainage and Sewer maintenance throughout the UK, the

company has rapidly expanded its activities, which today include:

• Drainage and Sewer Construction and Maintenance

• Ultra High Pressure Water Services

• Subsurface CCTV Surveillance

• Sand Blasting

• Specialist External Cleaning

• Specialist Internal Deep Cleaning

• Rotary Carpet Cleaning

• Specialist Restoration

• High Level Maintenance and Surveillance

• PPM & Re-Active Maintenance Services

• Dry Ice Solutions

Operating 24 hours a day 7 days a week allows us to fit into any of our client’s schedules and

with our staff all experienced in varying industry environments, this allows us to allocate

suitably trained people, in the right places and at convenient times.


Introduction to Dry Ice (The Substance)

Dry ice pellets are pure solid carbon dioxide and are made by decompressing liquid CO2 to

create CO2 snow. The snow is then compacted and extruded through a die plate to form solid

CO2 pellets.

Dry ice is unstable above minus 78.6 °C at atmospheric pressure, but instead of melting into

CO2 liquid when it warms up, it sublimes directly into CO2 gas. It is this sublimation process

that creates the cleaning effect when dry ice is used as a blast medium.

During blasting the pellets are accelerated to speeds between 200 and 300 m/s using

compressed air. They break up as they travel through the blaster and arrive at the work

surface as fast moving pinhead sized particles. The particles embed themselves into the

pores and cracks of any surface deposits and very quickly sublime into a much larger volume

of CO2 gas. This rapid generation of gas within an enclosed space breaks up the surface

deposit, releases its bond with the substrate and blows it away. The CO2 diffuses into the

atmosphere leaving no debris other than the material removed, which is usually found as a

fine dust.

Dry Ice is THE safe way to clean and restore:

• No abrasion to metals and most other materials

• No media ingress or debris

• No chemical or solvent action

• No media rebound and no secondary cleaning

• Suitable for use in open, live environments


Why Dry Ice?

• it is currently the only environmentally friendly way to clean industrial surfaces without

abrasion or the use of chemical solvents.

• It is completely non conductive and produces no friction therefore allowing cleaning in

live electrical and hazardous environments.

• It is completely non flammable

• The list of chemicals and solvents that have restricted use, or cannot be disposed of

without costly restrictions is increasing leaving dry ice being the only solution that is

SAFE.

• Advancements in machinery and planning methods will improve the “just in time”

capabilities of manufacturing plant, and on-line cleaning will be required to avoid

costly cleaning stoppages.

• Can be used in clinical and food environments. With the CO2 pellets being food

grade this allows the process to be undertaken in live food environments.

Where to use Dry Ice?

On practically all surfaces that are strong enough to resist the forces applied to the surface by

the impingement of the compressed air and the sublimation force of the dry ice. The

sublimation force can sometimes affect porous weak surfaces such as softwood, plaster

based compounds and materials containing a high percentage of soft filler and/or colorant, as

found in low cost plastic mouldings.

Where conventional cleaning causes unwanted changes to dimensions and surface finish dry

ice blasting is the ideal solution.

Where conventional cleaning introduces unwanted moisture, chemical attack or is a safety

hazard - dry ice blasting offers a dry, non toxic, safe solution.


What can it clean?

If the substrate is strong enough to resist the effect of the CO2 gas generation it will not be

damaged or abraded, and because CO2 is chemically inert, there will be no chemical

reactions to alter the substrate’s surface finish. Also, as sublimation takes place on first

impact, there is no secondary impact to cause undesirable effects to the surrounding area or

localised equipment, all of which makes the process safe and ideal for use in an open

environment, and as an in-situ tool cleaner.

Open cleaning of an automotive RIM moulding tool

If the substrate is porous, so that CO2 gas generation can also occur within its pores, the

cleaning may not be abrasion free. With porous substrates the deciding factor is the strength

of the material. A porous sintered metal will withstand the gas generation, but a friable

material like soft wood or plaster will not. Also, composite materials will show differing effects.

For example the talc will be leached out of the surface of talc filled plastic leaving the surface

roughened, whilst the same plastic without the talc, will clean without damage.


What surface deposits are hard to remove?

If the solid dry ice particles find it difficult to penetrate the layer that should be removed,

cleaning will be very slow. Typical materials that are hard to penetrate are oven cured paints

or enamels and elastic materials commonly used as sealants. Dry ice cleaning is generally

slower than an abrasive process on many materials and cannot create any specific surface

finish or standard, e.g. SA 2.5.

Can dry ice remove rust from steel?

Physically bonded rust will be removed from steel, but the underlying chemically etched

surface created by the rusting process will not be changed, leaving the steel surface clean but

still pitted.

What about corrosion?

The same applies to corroded materials, for example, oil, grease and road dirt can be

removed from an Aluminium engine block, but the corroded areas, generally caused by road

salt, can still be identified after cleaning.

Can Dry Ice remove paint from brickwork?

If the paint is soft and flaky it will be easy to remove, even if the bricks are on the soft side.

However, if the paint is tough and well adhered to the brickwork and the bricks are softer than

the paint skin, then the power required to break the paint away will also sometimes damage

the bricks. Having said this, the same will apply to any other form of blasting technique, and

when blasting brick or stone it should always be remembered that these materials, especially

when old, are rarely of consistent hardness.


How it works

History

The application of dry ice blasting started around 1980 in the United States as a method for

removing paint from aircraft wings without damaging the delicate airfoil surfaces.

The early blasting machines were generally designed as complete self-contained plants. They

converted liquid CO2 into dry ice, which was fed into a high-pressure carrier stream, and then

through a flexible hose to a blast nozzle. The nozzle finally accelerated the dry ice particles to

the surface to be blasted.

Today, dry ice is available from commercial sources in the form of small diameter pellets and

blasting machines have developed from the older large integrated plants to smaller more

mobile units that only transfer the pellets from a hopper to the nozzle. Modern blasters use a

dry ice transfer system that has either one or two flexible hoses connecting the blast unit to

the nozzle. They are generally known as single or dual hose blasters.

Single Hose Blaster (SHB)

This design of this blaster uses a mechanical shuttle or rotating air lock to transfer dry ice

pellets from a feeder system at atmospheric pressure to the carrier stream at high pressure.

The shuttle or rotating air lock must have a good sealing system that is able to cope with the

low dry ice temperature and mechanical wear. The moving parts are generally electrically

driven. The dry ice is carried to the nozzle in the carrier stream, which typically would be

compressed air flowing at around 200 ft3/min (5.7 m3/min) free air. At the nozzle, the exit

velocity is increased by a restriction through which both the dry ice and the carrier stream

flow.


Dual Hose Blaster (DHB)

This design can be used in two ways. Either the entire carrier stream goes through one hose

and the dry ice through the other, or some of the carrier stream is also used to assist the dry

ice passage through the second hose. In the first case, the dry ice is moved from the blaster

to the nozzle wholly by suction, but in the second case it is partly propelled or assisted in its

travel to the nozzle.

The Aeon Green Subsurface dry ice blaster is a dual hose machine, where the dry ice is

transferred only by suction, and the entire machine is pneumatically driven and controlled.

The dual hose design gives the system several advantages compared to single hose

machines:

Advantages of our Dual Hose Machines

Low Dry Ice Transfer Losses: The dry ice travels from the machine hopper to the nozzle

accompanied only by a small amount of naturally aspirated air. This reduces sublimation of

the dry ice en route to the nozzle. Typically, single hose systems have a high dry ice

consumption, often operating at up to 100 kg dry ice per hour, compared to the optimum rate

of 30 kg/h for the dual hose system. As the cost of dry ice is the major part of the total

operating cost of a blasting system this makes this blaster one of the most economical

available.

Low Risk of Blockage: The carrier stream and the dry ice come together at the last possible

moment in the nozzle, making blockage of the machine or hoses, either by the dry ice, or by

water ice formed within them, virtually impossible. Tests over multiple shifts have proven dual

hose blasters work continuously without blocking for long periods. This allows compressed

air, readily obtainable from standard hire compressors as used in the building industry, to be

used as the carrier stream without the need for more than a standard oil filter, water separator

and aftercooler.


Nozzle Design Advantages: The nozzle can be designed with a 90 degree angled outlet

making it possible to blast two parallel mould halves in an open press. Most of the other

systems cannot offer this facility as once accelerated the dry ice will be destroyed in an

angled nozzle by a cleaning action on the inside of the bend.

Very High Availability: Apart from simple pneumatic control components, dual hose blasters

have very few moving parts powered by an air motor to provide a continuous smooth metered

flow of dry ice to the point where it is further transported by suction. This drastically reduces

the chances of mechanical failure when compared to complex systems in which the dry ice

and carrier streams are mixed under high pressure conditions. In addition, as electrical power

is not required to run or control our blasters it can be used safely in remote locations.

Very Low Maintenance: The pneumatic control systems require only limited maintenance,

and as all component parts are standard readily available items sourced from global

suppliers, replacement in the event of failure is quick and straightforward.

Low Risk of Substrate Damage: Despite the above stated advantages of dual hose blasters

single hose units are still widely used. They are considered to be more powerful than dual

hose units when operating at the top end of their range, but care must be taken to ensure that

large dry ice or water ice particles do not damage the substrate. The development of larger

and more efficient nozzles has allowed us to match the top end performance of most single

hose units on the market today, and because the size of the ice particles emitted by dual

hose machines is considerably smaller, the risk of substrate damage is virtually eliminated.

Good Low Pressure Performance: The small pinhead sized dry ice particles emitted by our

dual hose units are also much better suited for operating at the lower end of their range when

delicate substrates are involved. Special dual hose systems are regularly built to operate at

2.0 bar air pressure to enable them to be used for electronic applications or deflashing

delicate plastic lenses without any risk of mechanical damage.

Even High Pressure Performance: The smooth flow of small dry ice particles coming

through the system nozzles also creates a much smoother cleaning performance at the top

end of the operating range. As single hose blasters emit an uneven flow of larger dry ice

particles they tend to miss some areas, which then require to be re-cleaned at the inspection

stage. This is generally unnecessary if a dual hose system is used, meaning the job is done

quicker with a much lower ice usage.


Applications

Dry Ice Blasting is used for an ever increasing number of applications. Some of the most

common are:

• Mould and Tool Cleaning

• Maintenance of Production Machinery

• Cleaning Production Machinery

• Removing Contaminants

• Cleaning Food Processing Equipment

• Removal of Coatings

• Refurbishment of Equipment for Re-sale

• Refurbishment and Maintenance

• Decontamination

The following guide lists some of the common industrial materials that can be removed by dry

ice blasting either from the surfaces to which they are applied, or cleaned off the equipment

or tooling used to apply or process them. Some typical examples are given, but the list is by

no means exhaustive and specific advice can be obtained by calling +44 203 463 8590 or e-

mailing [email protected] for advice.

Material Typical surfaces from which the material can be removed

Typical equipment from which the material can be cleaned

A Adhesives Glass, Metals, Painted surfaces,

Plastics

Applicators, Coating machines, Labeling

machines,

Animal feed Metals, Plastics, Rubbers Bagging machines, Extruders, Dryers

Asbestos Brick (with care), Concrete, Metals,

Piping. NOTE: Safety Regulations.

Boilers, Buildings, Heaters. NOTE: Safety

Regulations.

B Biscuit Conveyors, Moulds Baking ovens

Bitumen Concrete, Glass, Metals, Plastics Construction & Road surfacing equipment

Boiler scale Boiler internals Manifolds, Valves

C Carbon

deposits

Commutators, Electric and

Electronic components, Metals

Electric motor windings, Engine cylinder heads,

Generators, Printed circuit boards (PCB’s)

Chewing Gum Street paving Process & packaging equipment

Chocolate Conveyors, Moulds Process & coating equipment

Combustion

residues

Boiler membrane walls, Fire tubes,

Flues

Burners, Combustors, Exhaust systems,

Reaction chambers


Crude oil Holding vessels, Piping Drilling equipment, Valves

D Die Coatings Aluminium, Steel, GRP Casting & hot forming moulds

Dough Vessels, Mixers, Provers,

Conveyors, Mechanical parts

Kneading machines, Conveyor chains and

drives

F Fermentation

residues Vats

Distillery & brewing equipment, Fermentation

vessels

Fish residue Working surfaces Cutting and slicing equipment

Flavourings Glass, Plastics, Rubber, Stainless

steel Mixing & applicator equipment

Flour Millstones, Plastics, Rubber,

Stainless steel Milling & process equipment

Fluxes Printed circuit boards (PCB’s) PCB contact probes, PCB test equipment

Fluxes Brazed, Welded & micro-welded

components Brazing or Welding jigs and tools

Foam residues Cables, Ducting, Hydraulic hoses,

Mould vents EPS and EPU processing equipment

G Grease Practically all Acts as a degreasing process

L Logos Glass, Metals, Painted surfaces,

Plastics, Rubber Screen and tampon printed components

M Mastics Glass, Metals, Plastics, Painted

surfaces Applicators, Sealed components

Meat residues Bones, Hides, Metals, Plastics Animal by-products, Cutting and processing

equipment.

Milk scale Glass, Stainless steel, Plastics Processing equipment

Mineral oils Practically all especially as

degreasing process

Electrical and mechanical components,

Surfaces to be coated.

Mould release

agents

Low MP Alloys, Aluminium,

Composite tooling, GRP, Tool &

Stainless steel etc.

Moulding Tools and adjacent press equipment.

O Oil, Grease &

Dirt

Cables, Ducting, Drive shafts,

Gears, Hoses, Switchgear, Machine

components etc.

All machines and engines especially when

refurbishing

Organic

Growth

Ceramics, Metals, Stoneware,

Plastics

Holding tanks, Water storage and purification

equipment.

Overspray Glass, Metals, Painted surfaces

Plastics, Rubber Spraying equipment, Jigs, Tools etc.

P Paint Glass, Metals, Plastics, Rubber Conveyors, Sprayed components, Jigs, Pre-

painted panels

Paper Metals, Plastics, Painted surfaces, Drying rollers and evacuation hoods, Printing


residues Rubber presses

Powder build

up

Metals, Plastics, Painted surfaces,

Rubber

Food and powder processing machinery.

Pharmaceutical processing machinery

Printing inks Metals, Plastics, Painted surfaces,

Rubber Printing presses

Process

spillage Machinery surfaces Process machinery

Protective

coatings Metals, Plastics, Painted panels, Stored tools and equipment

R Radioactive

contamination Practically all

Generally tools and equipment that need to be

removed from active areas

Resin Metals

PCB curing ovens, Dies, tools and moulds

used to extrude or form resin containing

materials e.g. boards, composites, felts

Rubber Composites, Metals Moulding press tools and press ancillaries

S Smoke Glass, Metals, Plastics, Rubber,

Stone & Brickwork

Buildings, Ducting, Ovens, Machinery, Fire

damaged goods

Sugars &

Syrups Glass, Metals, Plastics, Rubber

Processing and transport vessels and

equipment

T Tar Glass, Metals, Plastics, Rubber Construction and processing equipment

V Vegetable oils Glass, Metals, Plastics, Rubber Food processing and frying equipment

W Wood pulp Glass, Metals, Plastics, Rubber Paper making machinery

Dry Ice Blasting - Aeon Green SubSurface

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