Interspiro Incurve SCBA Air Time Calculator

The Interspiro Incurve is the current flagship with a fully textile-free harness — all load-bearing components are non-textile, enabling complete wet decontamination. It supports HUD, PASS, and optional SpiroGuide telemetry, with cylinder options from 6.8L to 9.0L at 300 bar.

Textile-free harness: decontamination advantage

The Incurve harness uses no textile straps or fabric load-bearing components. All attachment points, shoulder supports, and waistbelt components are made from materials that can be washed, scrubbed, and verified clean under departmental decontamination protocols. Traditional textile harnesses can absorb carcinogens from smoke, PAHs from combustion, and chemical residues that are difficult to completely remove. For departments that have adopted post-fire gross decontamination as standard procedure, the Incurve significantly reduces the burden of harness decon compared to textile SCBA.

Incurve with SpiroGuide digital display

The Incurve is compatible with the SpiroGuide digital display system, which shows remaining air time as a calculated countdown rather than static pressure. The SpiroGuide calculates based on current real-time breathing rate — if you're breathing at 50 L/min, it shows remaining time at that rate. This calculator uses a fixed RMV preset. If you have SpiroGuide-equipped Incurve units, comparing SpiroGuide real-time readings against this calculator's preset estimates helps firefighters understand the relationship between their current breathing rate and remaining time.

Twin 3.4L cylinder pack vs 6.8L single: same air, different profile

The twin 3.4L cylinder pack provides exactly the same total water volume as the single 6.8L cylinder (6.8L total at 300 bar) — air time is identical. The twin pack splits the volume across two smaller cylinders arranged in a low-profile configuration. This is used where a lower back profile is needed (tight crawl spaces, confined access), or where weight distribution across two smaller cylinders is preferred. Air time calculation uses 6.8L regardless of whether single or twin pack is selected.

FAQ

Interspiro SCBA Air Time Calculator – Incurve, QS II & SpiroGuide II

Interspiro is a Swedish manufacturer with a long history in Scandinavian fire services and international markets. Their current lineup spans the Incurve (new flagship with textile-free harness), the QS II (proven workhorse), and the SpiroGuide II (telemetry-equipped version of the QS II). All are EN 137 Type 2 certified for structural firefighting. The air calculation is the same across models — what differs is harness design, electronics, and decontamination capability, not the fundamental cylinder and pressure physics.

Interspiro Incurve: textile-free harness and decontamination

The Interspiro Incurve is designed with a fully textile-free harness — straps, buckles, and load-bearing components are all non-textile materials. The primary benefit is decontamination: textile harnesses can absorb contaminants from smoke, HazMat exposures, and chemical environments, making complete decontamination difficult. The Incurve's harness can be fully washed and verified clean. For departments with high-risk exposure environments, this can reduce long-term contamination risk to personnel. Air time is unaffected by harness design.

QS II vs SpiroGuide II: same air, different information

The Interspiro QS II and SpiroGuide II share identical cylinder and air volume configurations. The SpiroGuide II adds an electronic monitoring unit with HUD and — in networked deployments — telemetry reporting. From an air time perspective, both units provide the same usable air for the same cylinder choice. The SpiroGuide II's added value is situational awareness and air accountability, not additional air supply.

SpiroGuide digital display and air management

The SpiroGuide digital display shows remaining air time as a countdown in minutes (calculated at current breathing rate) rather than just pressure in bar. This 'time remaining' display directly matches what this calculator estimates, but it updates continuously based on real breathing rate rather than a fixed RMV assumption. For training, comparing the SpiroGuide's real-time display to this calculator's preset RMV can help firefighters calibrate their personal RMV awareness.

QS II S-mask: ambient air hatch impact

Some Interspiro QS II configurations include an 'S-mask' with an ambient air hatch, allowing the wearer to briefly open the facepiece to ambient air (for communication, sampling, or short-duration tasks). When the ambient hatch is open, the mask is not operating as a positive-pressure SCBA — this does not affect cylinder air consumption, but it breaks the protection envelope. Air time estimates assume continuous closed-circuit positive-pressure operation.

Interspiro cylinder and twin pack options

The Interspiro Incurve and QS II support single cylinders (6.8L or 9.0L at 300 bar) and a twin 3.4L cylinder pack that provides equivalent volume to the standard 6.8L at 300 bar. The twin pack option splits volume across two smaller cylinders — useful where low profile is needed. Total air volume is the same: 6.8L water volume at 300 bar. This calculator treats them identically in terms of air time.

FAQ

This is an estimate based on the values you enter. Real-world air consumption changes with workload, stress, temperature, mask seal, leaks, and individual physiology. Always follow your SOPs and monitor your pressure gauge continuously.