Open Cell Pipe Insulation Compared To Closed Cell Pipe Insulation
Fiberglass Pipe Insulation and Mineral Wool Pipe Insulation are two types of open cell pipe insulation. Rubber Pipe Insulation, Foamglas Pipe Insulation, Urethane Pipe Insulation (also known as Trymer PIR or polyisocyanurate pipe insulation) and STYROFOAM Pipe Insulation (also known as XPS or Extruded Polystyrene) are examples of closed cell pipe insulation. In an effort to keep this post non-scientific and easy to understand, closed cell pipe insulation products do not allow water to flow through them while open cell pipe insulation products, most commonly fiberglass pipe insulation, allow water to pass through its fibers.
Why would anyone want an open cell pipe insulation which water can pass through? There are surprisingly a lot of reasons. First, fibrous products such as fiberglass pipe insulation and mineral wool pipe insulation are virtually non-combustible meaning they are the safest form of pipe insulation in the event of a fire. Second, they also have extremely high application temperatures. Fiberglass Pipe Insulation can withstand temperatures up to 1000F while Mineral Wool Pipe Insulation can reach temperatures up to 1200F. Some closed cell pipe insulation products, such as rubber pipe insulation, cannot exceed temperatures greater than 220F. Third, some open cell pipe insulations have very good insulation values (R-Values). Fourth, it is cost effective, especially compared to closed cell pipe insulation for larger bore pipes. Lastly, just because fiberglass pipe insulation systems are open cell does not mean that they cannot be used for condensation control.
As long as your open cell pipe insulation has a vapor barrier, which all standard stock fiberglass pipe insulation will have preinstalled, you can use fiberglass pipe insulation for condensation control provided the vapor barrier is completely sealed and the correct thickness of insulation is used. In the case of fiberglass pipe insulation, the vapor barrier is the white All Service Jacket (ASJ) that covers the fiberglass pipe insulation which is why it is extremely important to seal all seams with the provided ASJ tape laps. If you find your fiberglass pipe insulation system is condensating, you either have a break in your vapor barrier or you have the incorrect insulation thickness on the pipe.
While Fiberglass Pipe Insulation and other open cell pipe insulation products can be used for condensation, in high humidity environments it is often times best to use a closed cell pipe insulation such as rubber pipe insulation. Once humidity levels reach a certain point it is very challenging to eliminate condensation and it is best to have a product that will not be damaged by water.
For more information on condensation control view our blog post here.