Dry ice cleaning started in the US Aerospace Industries back in the ’60’s but did not become known in the UK until the ’90’s. Our company was founded in 1995 as Clean Surface Ltd and we designed and manufactured dry ice blast cleaning machines in Leicester.
Logically you need supplies of dry ice pellets, usually the 3 mm size, to clean with dry ice, but Clean Surface did not manufacture dry ice until 2008. As soon as we began to do so the business began to change, and over the intervening years we sold more and more dry ice, and the machine business eventually took second place.
Today over 85% of our turnover is dry ice and in 2018 we invested in two state of the art dry ice pelletizers each with a capacity of 350 kg/h giving sufficient capacity to produce over 1000 tonnes of pellets per year on a single shift basis. It was at this point we changed our name to Dry Ice Network (UK) Ltd to have a name more in line with what we do.
Although we are today predominantly a dry ice production company our past history has given us a lot of insight into dry ice blast cleaning. We have retained this knowledge and today support our customers, not only with the sale of dry ice, but also with sales and rental of dry ice cleaning equipment and contract cleaning using a Nationwide network of contractors.
Dry ice is a soft material with very unique properties. It can exist in our atmosphere for a short period of time as a solid with a temperature of -78.6 deg C whilst it slowly changes into a large volume of CO2 gas. Technically, this is called sublimation.
If small particles of dry ice are blasted at high speed on to a contaminated surface the impact energy will rapidly increases the state change from solid to gas, so as the small particles lodge themselves within the pores of the contamination large volumes of CO2 gas will be generated, which will break up the contaminant that will then be blown away by the driving force of the blast, typically compressed air.
The cleaning characteristics of dry ice:
Dry ice has a similar hardness to plaster so it does not clean abrasively. Contaminant can be removed from polished metal surfaces without affecting the surface finish as there is always a gas cushion between the dry ice and the substrate.
The contaminant must have some degree of porosity for the dry ice to get into it otherwise the CO2 gas will be generated on the surface of the contaminant, and it will not be removed.
The more difficult it is for the dry ice to penetrate the contaminant the longer the cleaning time will be.
Cleaning times cannot always be increased by increasing the dry ice flow as more dry ice will slow the impact speed unless the airflow is also increased. The most important factors that determine dry ice blasting efficiency are pellet speed and size at the point of impact. Very small high speed pellets are ideal for tough cleaning jobs.
The amount of compressed air and dry ice necessary to do a job in a sensible time may be well in excess of the acceptable cost of the cleaning job. Dry ice is not always economic for tough applications and it must always be remembered that it is a non abrasive blasting medium.
It is the non abrasive nature of the process that makes it so ideal for many applications where contaminants must be removed from process machinery with limited downtime. It can also be used in close proximity to electrics and electronics without fear of damage or short circuiting, and these are the jobs it is best suited to, rather than removing heavy deposits from items that have a low replacement value.