While polyethylene is chemically non-reactive, strong oxidizing agents have some effect over a long period of time. HDPE is more resistant to attack than LDPE. Maximum recommended temperature for HDPE is 82°C (180°F) and for LDPE is 49°C (120°F). Polypropylene is better than polyethylene in chemical and temperature resistance except with oxidizing agents where polyethylene is preferable. Maximum recommended temperature of polypropylene is 104°C (220°F).

Heat loss data: the amount of heat lost through evaporation for each open square foot of surface depends on the liquid temperature. Remember, balls will save 75% of loss.

Ball diameter: the percentage of area covered by the balls is independent of the ball diameter, being the ratio of a circle to the hexagon which surrounds it or p/2O 3 or 91%. Area covered = area of three 60° segments of circle divided by area of triangle = (3.p r2 ) / (1/2 . 2r . r3) = p/2O 3.