Safety at Our Core.

The AIRCAP 1™ by thrml.™ hot tub cover was intentionally engineered as a manual safety cover to comply with ASTM F1346-23 — the current (as of 2023) Standard Performance Specification for Safety Covers and Labeling Requirements for All Covers for Swimming Pools, Spas and Hot Tubs, published by ASTM International.

This standard sets rigorous performance, testing, and labeling criteria to reduce drowning risk by inhibiting access to the water for children under five years old when the cover is properly installed and used according to manufacturer instructions.

thrml.'s™ development team prioritized safety as a foundational requirement alongside thermal performance and sustainability. The AIRCAP 1™ is engineered to comply with ASTM F1346-23 through these key design elements:

The standard requires a safety cover to support a distributed load over a specified area without collapsing, tearing, or allowing breakthrough that could permit access to the water. That is a child-safety requirement, not a rating for use as a seat or platform: do not stand, sit, walk or climb on your AIRCAP 1™, and keep the locking tie-down straps fastened when the spa is not in use.

• AIRCAP 1™ incorporates a reinforced, high-density structural core (with air-capturing insulation layers) bonded to durable outer fabrics and perimeter reinforcements.
• This creates a rigid system designed to distribute weight evenly and prevent dangerous sagging or failure under load.

The cover must resist perimeter deflection and gaps that could allow a child (or a test probe simulating one) to slip through between the cover edge and the hot tub/spa wall.

• Custom-fit contours and precise edge profiling ensure a tight, secure seal around the hot tub's coping or shell.
• Our integrated heavy-duty heat-welded straps with keyed locks are designed to maintain constant downward pressure and eliminate hazardous openings, even under stress or attempted probing.

Fasteners must be designed to prevent easy removal by young children while allowing adult access.

• AIRCAP 1™ uses lockable, tamper-resistant straps with buckles — the same locks used by the hot tub and spa industry for decades.
• These mechanisms require deliberate adult action to release and are designed to meet the standard's child-inhibition goals.

The cover must not accumulate dangerous water volumes (e.g., from rain) that could create additional hazards or reduce effectiveness.

• The outer material and slight contouring promote proper drainage away from the center, preventing pooling while maintaining insulation integrity.

ASTM F1346-23 mandates specific permanent markings on the cover, including:

• Identification as a “safety cover” (when qualified).
• Manufacturer name, model, and compliance statement.
• Installation/use instructions and child-safety warnings.

AIRCAP 1™ is designed to carry this information on clearly visible heat-sealed labels, with icons for quick recognition.

By engineering the AIRCAP 1™ to comply with ASTM F1346-23, thrml.™ not only provides a high-performance thermal cover but also delivers genuine family protection. Some local building codes (e.g., in California) accept compliant safety covers in lieu of, or alongside, fencing for hot tubs and spas; whether a cover satisfies your local code is for your building department to say. This dual focus on safety and planetary health (energy efficiency and durable materials) makes the AIRCAP 1™ a standout in the replacement and OEM markets.