BW CLIP GAS DETECTOR UI
The Product
BW Clip is a low-cost, zero-maintenance gas detector equipped with one single sensor to monitor hydrogen sulphide, carbon monoxide, sulphur dioxide, or oxygen.
'Zero maintenance' means that once operational, the detector runs for a predetermined service life span (normally two years, with a three-year version also available) with no need to calibrate the sensor. The detector does not log data - in the event of exposure to gas, it records the associated time stamp and highest measured concentration, which means contact with a dock station to retrieve data is only required following an alarm.
Working with the industrial designer and the system architect of the product, I created the device's user interface and specified and help source the display necessary to carry that UI.
BW Clip is one of Honeywell's most competitive industrial safety products and its user experience had to be uncompromised within constraints of extremely low bill-of-material cost targets. For the UI this translates to an economical display with low power footprint.
User Personas
The user population has a spectrum of attitudes, background and motivations relevant to how they use the device. Among common users, the distinction between employed and contract workers may matter to marketing. As users however the characteristics experienced vs novice, and prudent vs cavalier matter more.
Within this two-dimensional diagram, each quadrant is represented by a fictitious user. The design specification elaborates on each.
Of the authorized users safety manager and industrial hygienist also fall into categories distinct from these descriptions. These individuals do not actually use the detectors, but they have an interest in (and responsibility for) their correct use by others. Whether a person with formal background, education and training in industrial or occupational hygiene is in the safety lead role, or 'merely' a line manager who rose through the ranks reflects an organization's maturity (and consequently the person's mandate) more than the role label.
Safety managers as people differ more along affinity with technology (with perhaps a generational component) and tolerance of process complexity.
The last user group, distributors or channel partners, exhibit varying levels of service centricity in their business model. Some are merely distributing / re-selling products whereas others offer bonus maintenance services for end-user businesses to whom the investment in maintenance infrastructure is not economical. The latter group is best helped by devices that work flawlessly within a user-friendly gas detection system (comprising dock stations and asset management software).
Features
Navigation
BW Clip's one single button limits UI navigation to three actions; (1) do nothing, (2) short press / click, and (3) long press / hold. The distinction between short and long press is made by a time based button handler. Button activation starts a timer. BW Clip interprets button release within the short press time brackets as 'click', and holding the button pressed through a countdown as 'hold'. Navigating a multi-layer menu structure is extremely cumbersome under those constraints, and not necessary for the device's limited feature set.
The button-click action allows the user to scan through key operational parameters of the device, and if a gas alarm has recently occurred, view the peak reading and time stamp associated with that event.
The button-hold action initiates a sensor reset to zero, which is sometimes necessary to stabilize a sensor with erratic response behaviour due to chemical or thermal stress.
Remaining Service Life
Once activated, BW Clip runs through its predetermined service life. Since the instrument cannot be switched off, it counts down its remaining service life span to its user. Until close to end of life this is of little concern, and remaining service life is expressed in months. The countdown switches to smaller time units during the last three months of life; initially, to provide sufficient notice to procure a replacement device in good time, and eventually to prevent users from carrying an instrument with critically low remaining service life into a hazardous location, where it could cease to function in mid-shift.
User Interface Animation
I vetted the proposed user interface design with individuals broadly representative of the user personas above, using a series of interactive mockups, with focus on:
Countdown length: safe from inadvertent operation, versus taxing on patience if too long?
Service life paradigm: Sufficient notice for re-procurement; desist from use in a hazardous area altogether if EOL imminent?
Non-compliance status indication: Pulse frequency adequate to attract attention?