ExLRT

Our long-term client MKTest Systems is a manufacturer of specialist electrical and electronic test equipment used in the construction and maintenance of aircraft, trains, and military equipment. One of their products – the Bond and Loop Resistance Tester (BLRT) is successfully deployed into production lines around the world. MKTest Systems recognized a commercial need for an ATEX compliant variant of the BLRT device for use in explosive atmospheres. These atmospheres are typically encountered around fueled aircraft.

To develop this specialist product MKTest Systems own electronics and software design team required support from an expert in intrinsic safety design for hazardous areas and an experienced product design consultancy. Hillside Product Design already had a successful track record of collaboration with MKTest Systems and was appointed to be the mechanical design team responsible for developing the three-dimensional form of the product and delivering it through tooling to production. The three separate design teams quickly gelled into a single team with a shared knowledge of the product, its users and the certification requirements for ATEX and IEC/EN 60079-11.

MKTest Systems recognized that there was a great opportunity to improve the ergonomic, aesthetic, and mechanical aspects of this new BLRT product, learning on the lessons that have been learned in the lifecycle of their original BLRT product.

Hillside Product Design undertook an iterative process of ergonomic study to identify the best possible arrangement for screens, buttons, battery access, flying leads and connections for accessories, portability and body-worn harnessing. The concepts were prototyped and reviewed several times within the design team using block foam models and 3D prints. These methods were chosen to keep pace with the fast-developing concept stage and culminated in looks-like/works-like, fully finished prototypes for presentation to stakeholders and potential customers external to the development team.

Once the broad concept was agreed on by all parties, it was developed through CAD and interim prototypes. Materials were meticulously selected and reviewed for their mechanical characteristics, electrical characteristics, aesthetics, and commercial factors. The shortlisted materials had to go through confirmation testing and Hillside undertook mechanical and chemical compatibility testing while others in the team looked at electrical characteristics. 

One key part of the certification is a cold temperature drop test. This can only be done on the final product and is almost the final test before certification. It was vital that the product did not fail, and several tests using CNC machined prototypes were done during development to reduce this risk to a minimum.

Hillside nominated a preferred toolmaker and moulding partner who could support the delivery of the tooling and parts in time for the pre booked compliance testing. To miss the test date would have caused extensive problems so it was vital that Hillside supported the toolmaker in the tool design and by being on site during the latter stages of toolmaking, prior to moulding. Components were hand delivered to MKTest Systems on time, the product built and the testing went ahead as booked. 

One of the key elements of designing for intrinsic safety is to maintain a design file and submit extensive documentation describing the product to the examiner. HPDL supplied all necessary files and documentation relating to the mechanical design and supported the team with other images and illustration supporting their documentation to complete the submission.

This BLRT product is now called the ExLRT and is approved and used by The Boeing Company. It can be found here.