Overfill Prevention Valve Calculator


Note: This calculator is intended to be used as a reference only in states following CARB specifications


Using a tape measure, record dimension A as specified in Figure 1 below. Refer to tank manufacturer chart for dimension B.

Input the dimensions into the boxes below in decimal values.

Click the "Calculate" button below, then scroll down to see the cutting instructions and calculated dimensions.



Locate the 95% fill mark on the overfill prevention valve. Measure from the 95% fill mark up to the Top Tube Height as shown in the diagram below. This value will be calculated for you in the Top Tube Height field below.

NOTE: The Top Tube Height must be cut before cutting the total tube length.

Measure from the cut top tube down to the calculated Total Tube Length as is shown in the figure below. This value will be calculated for you in the Total Tube Length field below. Cut the bottom tube either straight or at a 45 degree angle down towards the bottom of the tube as show below.



Sealing surface is the located at the top of the containment nipple for screw-on spill containers and at the top of the riser for slip-on spill containers.


Sealing surface is located on the horizontal surface just below the riser seal.