EPF is subject to the numerous tests and standards formulated by the American Society for Testing and Materials (ASTM) for plastics in general. Some of these standards concern EPF in particular because of its unique properties, yet some of the tests applied to EPF were developed to measure the properties of other plastics.
The polystyrene melt is tested to determine whether it is sufficiently viscous to produce EPF with the desired properties. Further, the subsequent polystyrene beads must be of uniform size. The standard for perfectly spherical beads is based on those formed in space shuttle experiments under conditions of zero-gravity. Molded EPF is also tested for strength, flammability, and density, which is particularly important then testing flotation devices. EPF's resiliency is measured by banging a pendulum against the
material and observing how far it rebounds. EPF is then tested for porosity. This involves determining how many open and closed cells there are, after considering the surface area of the product and the number of cells cut by fashioning. Permeability is then tested. A simple test involves placing a piece of EPF into a substance and then measuring how much of it is absorbed.
Thermal conductivity is important whenever EPF is used for insulation. Cellular plastics have the lowest thermal conductivity (transmission of heat) of any solid material known. They insulate so well that testing for thermal conductivity is time-consuming, even when thin sheets are used. The thin (.79-2 inches or 2-5 centimeters) sheet of EPF is placed next to a heater plate, and both are enclosed by cold plates to minimize heat loss. A controlled, small amount of heat is then applied to one side of the sheet, and, after several hours, the amount of heat penetrating to the other side is measured.
Of course, all data must meet the standards for E.