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BV Precast
User Guide

Calculating the volume of the void left by a block-out or void former in a manhole side wall can be difficult. This calculator helps anyone solve this problem quickly and easily.

1. Select the inside diameter in inches of the manhole structure being used. The wall thickness automatically fills in when diameter is selected.
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2. Enter the concrete density in lb/ft3.
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3. Enter the diameter of the block-out(s).
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4. Enter up to four block-out diameters. For 8” sanitary pipe boots, a 12” block-out is normally used.

The result is the total volume of all block-outs entered. If the manhole being analyzed has four block-outs, the estimated volume represents the total volume of the four block-out diameters entered.

If the block-out is tapered, i.e. 30” diameter on the inside and 24” diameter on the outside, use the average of the two when solving for the volume. In this example, a 27” diameter block-out should be used.
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An iPhone App for the precast concrete industry. Possibly the first precast concrete industry specific app available for iOS devices (iPhone, iPad, and iPod Touch).
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