The cleanliness requirements of the system ruled out the use of grease during manufacture, requiring our engineers to develop a new flange face sealing technique without the use of lubricant. Our team applied their creative expertise to introduce an alternative method which achieved extremely high leak-tightness at a rate of 10-9mbar litres/second, equivalent to less than one part per million per year at atmospheric pressure or – alternatively – more than 1,000 years to lose 1% of the helium inventory.
To achieve the hydrocarbon cleanliness requirements of the system, GRE instigated the creation of a cleaning regime which was approved by the client and carried out prior to build completion. Following cleaning, the system was tested for remaining hydrocarbon content using residual gas analysis techniques. This process is able to identify, at the atomic level, the presence of undesirable compounds or elements which could damage the contained optical equipment. The system passed with flying colours.
Following build completion, the customer attended factory acceptance testing carried out at our facility over two days. This included: testing the ability of both systems to respond to temperature and flow requirements, control the transition to these, and stabilise; verifying the control accuracy to +/-0.1K of setpoint within five minutes; testing the stability of the gradual cooling rate and testing the numerous alarm setpoints within the control system. Following client sign-off, we carried out further successful site acceptance testing at the client’s facility.