TM 1007:2010

Water Displacement

Final version: 09/06/2010

Background and purpose

The yield of the foam can be determined in a various ways; as a joint yield or as a free foamed yield. In the curing process the foam changes its dimensions and the final shape of the cured foam is irregular therefore problems with the determination of the foam’s volume may occur. The purpose of this Guide is to describe the water displacement test method for measuring the irregular shaped foam’s yield.

Tools

• 200 litre drum containing water.
  
  
• Grid basket that fits in the drum.
  
  
• Bucket for water which flows out from the drum.
  
  
• Weighting scale.
  

Procedure

Test description:

1. Fill the drum with water up to the drainpipe level.
   
   
2. Open the drainpipe.
   
   
3. Put the grid basket in the drum in such a way that it is totally under the water level and the excess water flows out of the drain (to eliminate the measurement of errors due to tool volume).
   
   
4. Wait until the drain stops issuing water, so that the water level is just below the drain pipe. Take the basket out of the water and place one foam piece (or more if possible) in it.
   
   
5. Put the basket back in the drum in such a way that it is fully under water.
   
   
6. Collect the water that flows out of the drain.
   
   
7. Weigh the collected amount of water.
   
   
8. Repeat steps 1 - 7 for each piece of foam.
   
   

Calculation

The weight of all collected water is the measure for the volumetric yield of the free foamed foam:

in which:

Y(l)            = volumetric yield in litre [l]
m _water = weight of the collected water in kilogram [kg]
∂ _water = density of the water at test temperature in [kg/l]

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