14-May-2010

HiTech provides solutions for vibration and humidity

Abstract

Appropriately named HiTech Controlled Environments, of Bury St Edmonds, UK has carried out work in several hi-tech industries, including sectors where vibration and humidity can be an issue

One of the laser facilities with vibration cushioning

Appropriately named HiTech Controlled Environments, of Bury St Edmonds, UK has carried out work in several hi-tech industries, including sectors where vibration and humidity can be an issue.

The company was asked to provide an environment for the manufacture of holographic products at OpTic Technium's Centre for Modern Optics in North Wales and in this project vibration was the key issue. The lasers that produce the holograms are so sensitive that the slightest vibration would destroy the work being undertaken and that includes vibration caused by air movement through the rooms.

The vibration issue was solved by isolating the lasers from the structure. This was achieved by floating the laser tables on a self-levelling cushion. But the cleanroom also needed quite a high level of air movement according to the level of classification.

HiTech is a specialist in controlling humidity and in one of its most innovative builds, it was able to maintain a Class 7 environment with no air movement at all. The company was also involved in the commissioning, setting the facility to work.

In another hi-tech project, the company was approached by Hypoguard, a member of the medical imaging services group Medisys, for an ISO Class 7 cleanroom with an internal room condition of 20C at 5% RH. The maximum condition was to be 8% RH with an alarm at 10% RH at 20C.

HiTech built the cleanroom using its standard modular panels and static dissipative vinyl flooring that was covered up the walls to provide a complete vapour barrier. To limit further the number of barrier penetrations through the building fabric, all the light and electrical fittings were surface mounted and rated not less than IP65.

At the heart of the air conditioning system is a desiccant dehumidifier operating in a modulating manner in response to a dewpoint sensor located in the return air ducting. The dewpoint sensor was used because humidity sensors do not give the accuracy of control at the extremes of their operating range. The dry air from the dehumidifier is then driven through a cooling coil to cool the air to a usable temperature before it enters the cleanroom. The cooling medium is chilled water supplied by an air-cooled liquid chiller operating on R407c refrigerant.

A computerised control system provides data logging for QA and QC, as well as alarm handling and remote control. The facilities have been granted a licence by the US FDA and are controlling to within 0.5% relative humidity during peak summer ambient conditions. In addition to working with the electronics, fibre optics, lasers and communications sectors, the company also designs, builds and validates cleanrooms for pharmaceutical production, biotechnology and medical device manufacture.

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