How to Figure Drop Factor

Knowing the drop factor, or drip factor, of the tubing used in intravenous treatments is an important part of properly calibrating the infusion set delivering the dosage. All manufacturers print the drop factor of their medical tubing very clearly on the packaging. Standard drop factors are measure in drops per milliliter (gtt/mL) and come in sizes of 10, 15, 20 and 60. Though the drop factor is always printed on the label, it is possible to manually figure the drop factor of a tube by using the flow rate equation.

Things You'll Need

• Calculator (optional)

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Instructions

• 1

  Write down the flow rate equation. The volume in milliliters (V) divided by the time in minutes (T) multiplied by the drop factor of the tubing in drops per milliliter (Df) is equal to the flow rate in drops per minute(Y) or (V/T * Df = Y).

• 2

  Substitute the known variables of volume, time and flow rate. For example, the volume is 1200 mL over 360 minutes with a flow rate of 50 drops per minute (1200/360 * Df = 50).

• 3

  Divide the volume by the time. In this case, 1200 mL / 360 minutes is equal to approximately 3.3 (3.3 * Df = 50).

• 4

  Divide the flow rate by the quotient determined in the previous step, to figure the drop factor of the tubing used in the treatment. For the example, 50 drops per minute divided by 3.3 (Df = 50/3.3) which equals 15 (Df = 15).