iMist & Cover Plates

At iMist, we’re often asked why our nozzles aren’t “concealed” or flush with a cover plate on the ceiling. Many consider this the most aesthetically pleasing option.

When we entered the domestic and residential fire suppression market, we carefully explored the option of concealed or flush plate-type nozzles. While such designs can look sleek, after thorough consideration, we decided not to pursue them. This decision has, in some cases, resulted in large projects being awarded to competitors using concealed nozzles.

We want our customers to understand why aesthetics had to take a back seat to safety and performance. iMist does not use concealed or flush plate nozzles for four key reasons.

1. Compliance with BS 8458:2015 – Quick Response

Section 3.29.1 of BS 8458:2015 states that a watermist nozzle must operate via an integral quick response thermal release element (the bulb). If the bulb is placed above a cover plate, its classification changes from “quick response” to unrated, reducing the system’s effectiveness in detecting fire quickly.

2. Maintenance and Inspection

BS 8458:2015 section 8.1 requires that each nozzle be checked during service to ensure its heat-sensing capacity and spray pattern are not impeded. With nozzles hidden above cover plates, this would require physically removing every plate during inspections. By keeping the iMist nozzle exposed below ceiling level, simple visual checks are all that is needed to confirm the system is ready to operate.

3. Optimal Fire Response

Fire suppression systems are most effective in the earliest stages of a fire. The bulb in the nozzle is designed to activate when exposed to a pre-determined temperature. If it is concealed above a cover plate, it is partially shielded from the rising heat, which delays activation. The iMist nozzle is intentionally positioned below ceiling level to ensure it is directly exposed to hot air, minimising any delay in system response.

4. Risk of Bulb Obstruction

Cover plates can sometimes become fixed in place by end users or contractors, often unintentionally, through paint or sealant in the small gaps around the plate. If this happens, the plate cannot drop at the design temperature, meaning the bulb may never be exposed to heat, preventing system activation. This risk overrides any aesthetic benefit and was the deciding factor in our decision to avoid concealed or flush nozzles entirely.

Putting Safety First

While concealed or flush plate nozzles may look neater, iMist prioritises reliability and life-saving performance above aesthetics. Our exposed nozzles are designed to ensure your system works exactly as intended every time.