Spray polyurethane foam (SPF) is an insulation material made on site: two liquids are sprayed onto a surface, react within seconds and expand into a continuous rigid layer that bonds to the substrate without joints. That is why it is one of the most widely used thermal-insulation methods on roofs, warehouses and cold rooms.
Components A and B
- Component A (ISO): the isocyanate.
- Component B (POL): the polyol blend, containing catalysts, blowing agents and additives.
The reaction only starts when the two meet, so they travel separately until the moment of spraying and come together in the mixing chamber of the spray gun.
What does the spray machine do?
A spray foam machine (a proportioner) does more than spray. It controls three things the job depends on:
- A fixed mixing ratio — 1:1 for most foam systems.
- The right temperature — preheaters heat both components, and the heated hose holds that heat up to the gun.
- Enough pressure — to mix the components thoroughly and atomise them.
A problem with any one of these shows up straight away in the foam: poor adhesion, an irregular cell structure, or material that has not fully reacted.
The parts of a spray line
| Part | Job |
|---|---|
| Transfer pumps | Draw both components from the drums to the machine |
| Machine | Heats and pumps the components at the set ratio and pressure |
| Heated hose | Carries the components and keeps them hot |
| Whip hose | A short flexible section before the gun |
| Spray gun | Mixes and sprays the components |
The EP 10 has 56 L integrated tanks and needs no transfer pumps; hydraulic machines such as the KPX 20 work with TP pumps.
How machines differ
Spray foam machines mainly differ in power supply, pump system (electric or hydraulic), output and maximum hose length. In the PUSMAK range, maximum flow runs from 4.5 kg/min on the EP 10 to 14.8 kg/min on the KPX 50.
To compare models side by side, see spray foam machines, or read how to choose a spray foam machine.
