Material Selection by Application
Cold pipe applications — refrigeration, chilled water, heat pumps — have one non-negotiable requirement: closed-cell insulation with a built-in vapour barrier. Open-cell materials absorb moisture, lose thermal performance, and fail. For hot applications above 105°C or fire-critical areas, mineral wool is the correct choice.
Quick Selection Table
| Application | Temperature | Best Material | Thickness |
|---|---|---|---|
| Refrigeration | -30 to +10°C | K-FLEX ST/SK | 19–32mm |
| Chilled water | 6–12°C | K-FLEX ST/SK | 19–25mm |
| HVAC heating | 40–80°C | K-FLEX ST or K-Rock | 13–19mm |
| Heat pump suction | -10 to +10°C | K-FLEX ST / Solar HT | 13–19mm |
| Heat pump discharge | 40–65°C | K-FLEX ST / Solar HT | 13mm |
| High-temp steam (>105°C) | 100–250°C | K-Rock Mineral Wool | 25–50mm |
Refrigeration Lines (-30°C to +10°C)
Closed-cell elastomeric only. The low operating temperatures create significant condensation risk — any moisture path through the insulation will result in ice formation inside the insulation and eventual failure. All joints must be sealed with K-FLEX K-420 adhesive or use the SK self-seal range. Increase thickness to 25–32mm for low-temperature applications (-20°C and below) or high-humidity environments.
Chilled Water Systems (6–12°C)
Same material requirement as refrigeration — closed-cell elastomeric, all joints sealed. Standard thickness 19mm; increase to 25mm in plant rooms with high humidity or poor ventilation. The SK self-seal range speeds up installation significantly on long chilled water runs. Don't leave valves and fittings uninsulated — they're the most common condensation failure points.
HVAC Heating (40–80°C)
Either elastomeric or mineral wool is acceptable depending on fire requirements. Use K-FLEX ST elastomeric where Class O/1 fire rating is acceptable and fast installation is a priority. Use K-Rock mineral wool where non-combustible A1/A2 rating is required — plant rooms, commercial risers, fire-critical areas.
Heat Pump Lines
Both suction and discharge lines need insulating. Suction line runs cold — closed-cell elastomeric, 13–19mm. Discharge line runs hot — elastomeric, 13mm. For outdoor runs, use K-FLEX Solar HT which is UV-stabilised — standard elastomeric degrades in sunlight within months.
Key Installation Rules for Cold Pipes
- Closed-cell material only — no open-cell foam, fibreglass, or mineral wool without vapour barrier
- Seal every joint with K-420 adhesive or use SK self-seal — an unsealed joint is a vapour path to the pipe
- Insulate all valves, fittings, and elbows — gaps cause dripping
- Increase thickness in high-humidity environments
- Use Solar HT outdoors — standard elastomeric is not UV-resistant
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