jan 10, 2023
Equipment of areas with controlled environmental working conditions
Controlled working environments – from temperature and humidity zones to advanced cleanroom facilities – are becoming an increasingly common requirement across a wide range of industries as technology advances. What until recently seemed to be a rarity – something used only in global corporations, pharmaceuticals or electronics, is now becoming standard for many manufacturing companies.
It can be observed that in many industries, technology now requires, at certain stages, a high degree of air purity or the maintenance of other specific parameters for the working environment or the storage of components and products. The consequence of all this is an increasing demand for spaces with controlled parameters and their equipment. In this paper, we will look at the equipment required to create such a space from scratch and the alternative: ready-made mobile cleanbox solutions.
When discussing the equipment required to create a space with controlled working environment parameters, it is important to start with the entrance. A common solution – used, for example, in clean zones – are airshower-type personnel locks. They limit the exchange of air between two zones as a person passes between them. A popular model on the Polish market – the CR-GAS-004 – has approximate overall dimensions of 1000x1400x2200 mm and allows one person to pass through in a single cycle. In its design, the unit consists of two doors arranged in a line and a supply chamber between them. A person passing from one zone to another enters the airlock. When the door closes, an automatic supply of filtered air directed at him or her is activated.
If you want to keep air exchange to a minimum for the movement of small objects between zones, you can use smaller passageways – available on the market as so-called ‘pass windows’. There are three types: passive, active (over or under-pressure) and active with an integrated internal air purification system filtered by an absolute HEPA filter. The passive model – which can be understood as the basic solution – consists of two staggered doors and a chamber between them. The principle of operation is the so-called cross protection – ensuring that only one of the doors can be opened at a time.
The active version of this device – sometimes referred to as a pressurised version – allows the unit to be connected to a functioning supply and extract system in the building. Using fixed discharge dampers, either increased or decreased pressure is achieved inside the chamber relative to adjacent spaces.
The correct setting of the pressure level in the rooms to be separated and inside the infeed window allows the required level of cleanliness to be maintained. Depending on the needs, such sequences are set up as a cascade, where room one has a lower pressure than inside the airlock and room two, behind the airlock, has a higher pressure, or as a buffer – where the airlock has either a higher or lower pressure than the adjacent rooms.
The last – third – version of this unit – thanks to the built-in pre-filtration and HEPA system – allows a constant – i.e. forced, even air flow from top to bottom. The air is collected by means of perforations located at the bottom of the chamber, where it is drawn in again, resulting in closed circulation. This solution is particularly important for cleanrooms where the amount of particulate matter (dust) in the air must be kept to a minimum.
Of course, when it comes to cleanroom type areas, filter fans are not just used in aisles and serving windows. Spaces of this type require a precisely designed and maintained ventilation and air filtration system.
There are ready-to-install units on the market that combine a fan with a filter module equipped with a pre-filter and HEPA filter in a single module. These are used in particular above workstations as a laminar air supply – that is, one that does not cause air turbulence.
Devices of this type make it possible to achieve the correct air purity in a specific zone – e.g. a sampling area. These are, of course, only examples of finished products that can be used in the construction from scratch or modernisation of a conventional space with controlled environmental parameters. By conventional here, we mean a solution in which parameters are maintained throughout entire production halls, with areas of up to hundreds of square metres.
Looking at the issue, it is still possible to consider a newer approach to the problem of maintaining a controlled working environment. When it comes to controlling certain parameters – particularly air purity – it is now possible to achieve similar or even the same results using so-called cleanboxes – i.e. much smaller, mobile solutions.
Their key advantage is the incomparably lower cost of construction, implementation in the company and subsequent maintenance. Conventional spaces involve the entire construction process and its full adaptation – and thus building designs, permits and the construction itself. In contrast, these cleanboxes – modular, mobile structures that allow the creation of a clean area of a few square metres – can be introduced into a company almost immediately and at a fraction of the cost. Of course, the use of such smaller solutions requires the user to analyse his or her production process and determine the stages – the ranges of the process – when the application of controlled conditions is actually necessary. An example from the electronics manufacturing industry would be the assembly stage of touchscreens.
After a proper analysis of a company’s process, it can often be seen that there is no need to build or maintain conventional zones of 100, 200 or 1,000 m2 – and that a much smaller mobile solution of 2x2m or 2.5×2.5m or 3x3m or 5x3m set up at a key point in the production line will suffice.
The cleanbox solution also has the advantage of being mobile. It is a lightweight construction that can be adapted to other work and can be moved to another location if production changes. If the cleanbox should prove too small over time as the company grows, it can be expanded at no great expense. When cleanboxes are used to create so-called clean areas – they allow cleanliness classes up to ISO 6, although in practice classes 8 and 7 are most commonly used – which is sufficient for most applications. A laminar chamber can also be placed in the cleanbox space, where even higher ISO classes can be achieved. In this setting, the air is filtered twice – creating zones of progressive cleanliness.
In doing so, it should be noted that simply creating a suitable space with controlled parameters does not ensure that they are maintained. It is necessary to continuously implement procedures that strictly define what it is supposed to look like to work inside the room, how the employees in the room should behave, as well as their periodic maintenance and cleaning. The key here is to select the right project developer and subsequent partner during the implementation and maintenance of the room’s functionality. The RENEX Group’s mission is to provide comprehensive support to its partners. As part of its CLEANROOM brand, it designs and supplies cleanrooms with controlled parameters, in particular cleanrooms – both in the form of cleanrooms and cleanboxes, supplies furniture, equipment and clothing, and provides a wide range of training, maintenance and consultancy services in this area.
The RENEX Group is also a manufacturer of specialised antistatic clothing enabling work, among other things, in clean areas, including the so-called EPA zones in which electronics sensitive to electrostatic discharges are manufactured and repaired. All of this makes the offer provided comprehensive – covering the scope from design, through execution and equipment, to subsequent servicing. If you are interested, please contact RENEX Technical and Sales Advisors. Find out more at www.renex.pl