TM 1003:2010

Determination of the free foamed yield of a polyurethane foam canister - box test

Final version - 02/03/2010

Background and purpose:

The yield of canister PU-foam is often an important point for customers buying the product. Information on labels concerning yield are often derived from laboratory tests that were done under ideal circumstances, i.e. circumstances to get the highest possible yield. This test method was developed to have a reproducible way of measuring the free-foamed volumetric yield.

Apparatus and material:

• Wooden box with inner dimension of:
  Box type 1: 400 mm x 400 mm x 400 mm (filling volume >700 ml)           or
  Box type 2: 300 mm x 300 mm x 300 mm (filling volume 400 – 700 ml)  or
  Box type 3: 250 mm x 250 mm x 250 mm (filling volume < 400 ml)

• Wrapping (Kraft) paper
• Vaporizer, containing water

Procedure:

1. Preparation:
   
   Cover the inside of the box with wrapping (Kraft) paper.
   Acclimatise test canister and box at 23 °C and 50% RH.
   
   
   
2. Test description:
   
   Filling the box with foam.
   
   
   • Test at 23 °C and 50 %RH (note the exact temperature and relative humidity).
   • Moisten the inside covering of the box with 10 ± 1 g of water.
   • Shake the test canister at least 20 times.
   • Foam a layer of 10-12 beads for adapter foam with ~ 1cm space between the beads, and 12–14 beads for gun foam without space between the beads. Shot foam from a distance of circa 1 cm to the bottom of the box. Spraying time is 30-40 seconds per layer (for surface 400 mm x 400 mm, smaller boxes accordingly less - see also Figure 1). Spray with maximum one interruption to allow dispensing at the bottom of the box.
   • Spray immediately water on this layer (10 ± 1 g for box type1, 7 ± 1g for box type 2 and 4 ± 1 g for the box type 3).
   • Wait 3 minutes.
   • Shake the canister again.
   • Foam a next layer perpendicularly on the previous layer in the same manner as the step 4. Don’t spray next layer into the froth of the former layer.
   • Repeat steps 5 - 8 till the can is empty.
   • Allow the foam to cure in the box for 24 hours.
   • Take the foam out of the box (see also Figure 2).
   • Remove the paper from the foam as much as possible.
   • Cut the foam top down and crosswise in 4 equal pieces.
   • Measure the total volume of the foam pieces using water displacement test method (see OCF TM 1007).

Figure 1: Test box and plant sprayer

Figure 2: Cured foam in test box

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