Spray Polyurethane Foam (SPF) insulation is an increasingly popular construction material for both commercial and residential buildings. For more than 35 years, SPF has been installed in direct contact with pipe and fittings from BlazeMaster® Fire Protection Systems. However, we regularly receive questions about this topic, so we compiled answers to those we hear most often.
Yes. In 2009, Lubrizol helped the Spray Polyurethane Foam Alliance (SPFA) assess potential chemical compatibility issues in using SPF with BlazeMaster Fire Sprinkler Systems and other Lubrizol brands. The study concluded that SPF did not pose chemical compatibility issues when two-component foams are properly mixed and applied.
Keep in mind that SPF brands vary somewhat, so be sure to consult the manufacturer’s guidelines to ensure compatibility. Lubrizol’s FBC™ System Compatible Program provides general guidance on use of SPF under Other Compatibility Topics.
SPF insulation is typically applied with equipment that mixes two liquid chemical components, which are then spread with a spray nozzle. The two components react with each other almost immediately and foam up to create a solid structure. This process creates good insulating properties – and a lot of heat that does not dissipate quickly. Proper installation technique, described below, is important to ensuring the heat does not damage the CPVC.
It’s important to keep the fire sprinkler system empty of water and unpressurized when the insulation is installed. The pipe may contain air, so long as it is not pressurized. If the SPF temperatures exceed the CPVC softening point, pipe and fitting walls could become stretch and thin, leading to a rupture. If empty and unpressurized when temperatures rise above the softening point, the pipe wall won’t thin, and the CPVC will harden back up as the temperature falls.
SPF installers must follow manufacturer instructions regarding layer thicknesses and wait times between applications. Installers should apply the first pass so that it just touches the pipe. After sufficient cooling, apply a second pass to achieve final thickness (Figure 1). An optional protective pass over the pipe may be used between the passes, as shown by the dashed red line.
It’s essential to avoid application where pipe is positioned at the thickness of the pass where it will be exposed to high temperatures as the SPF cures (Figure 2).
A Lubrizol study found that, for the products tested, the spray pass thickness should not exceed:
Be sure to follow manufacturer guidelines for wait time between application passes.
SPF installers must take extra care in awkward building cavities where keeping the application thickness below the allowable maximum may be difficult. For more details about open-cell and closed-cell SPF, visit spraypolyurethane.org.
Fire sprinkler system designers should consider whether thermal expansion is needed to compensate for heat generated by SPF installation. That’s especially important when long runs of pipe will be covered with SPF. Expansion loops or offsets may be needed to address heat concerns, especially in areas such as elbow or tee fittings where expansion is restrained. Consult the pipe manufacturers’ manuals about compensating for thermal expansion.
Do you have additional questions about SPF and BlazeMaster CPVC? Please click “Request a Consultation” to reach out to our team of experts.