“Flow Ratio” Runs
What is it?
Why do it?
Flow Rate Ratio - How to Do It
Flow Rate Ratio test and the
Pneumatic Lift Option
Flow rate ratio (FR) is a tests used to obtain two flow rates at two different
stresses or loads, of generally a 10:1 ratio. For example, the first might be a
2,160gram weight with the second being a 2,160gram weight. If you divide the
high load flow rate by the first, you have flow rate ratio or one number relating
the slope of the flow curve.
One example of this test is as follows, tapes are available with a ¼" flag and a
1" flag right after it. The test is started using a low weight. Once the ¼" flag
passes the eye, the low weight is removed and the high load is applied or a high
load is added. Immediately after the second flag passes, the two flow rates are
calculated and the flow rate ratio is computed and printed.
It is strongly suggested that this test be conducted if you have purchased the
Pneumatic lift option from DYNISCO POLYMER TEST, Inc. The weights
involved are quite heavy and dangerous for an operator to be routinely lifting.
The pneumatic lift automatically and safely lifts the weights as needed.
Assess shear thinning behavior of material
Correlation to MWD
You must have a Flow Ratio capable instrument. (Note: Flow Ratio can only be
run in one pass in Method B).
In a Flow Ratio test, when the melt time is over, the sample data collection time
starts. Flow Ratio programs execute in a Method B mode using two optical flags
or two Digital Encoder flags. Between the first and second flag, the second
weight will automatically be lowered by the pneumatic lift system onto the
plunger. After the flags have been processed, the instrument will compute and
display the two MFR’s, two MVI’s if selected and the Flow Ratio before
proceeding to the next run.
1.) In the EDIT mode select RATIO for method. This triggers the computer to
perform a new test.
2.) The addition of FLG LENGTH HI and LOAD HI appear in the edit mode.
Enter the appropriate values for these parameters.
Series 4000 Melt Indexer Operation Manual “Flow Ratio” Runs
39
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