Reference Height. The distance from the reference mark to the tank bottom or datum plate. After the
reference height is established, it is stenciled in a conspicuous place adjacent to the gaging hatch.
Innage Tape and Bob. A graduated, metallic tape and pointed bob used to determine the amount of
innage in a bulk storage tank.
Outage Tape and Bob. A graduated, metallic tape and flat bob used to determine the amount of ullage
in a bulk storage tank.
Product-Indicating Paste. A chemical paste used in measuring the amount of liquid petroleum in a
storage tank. It will change color when it comes in contact with a petroleum product.
Water-Indicating Paste. A chemical paste used to differentiate between liquid petroleum product and
water. The paste changes color when it comes in contact with water, but is not affected by petroleum
Tape Cut. The line made on the tape measuring scale by the product being measured.
Bob Cut. The line made on the bob by the BS&W being measured.
Opening Gage. A gage of a product taken before delivery, issue, or receipt of a product.
Closing Gage. A gage of product taken after delivery, issue, or receipt of a product.
Total Measured Quantity. Total measured quantity is the volume of product and BS&W in a tank at the
observed temperature of the product at the time of gaging. It is usually obtained from a tank's capacity
table or strapping chart.
Bottom Sediment and Water (BS&W). The amount of sediment and water measured in the bottom of a
Net Volume Uncorrected. The volume of product in a storage tank at the observed temperature.
Net Quantity at 60F. The net volume, uncorrected and converted to the equivalent volume at 60F.
Gaging Equipment. Items of gaging equipment are described below.
Innage Tape and Bob (Figure 6-7). The steel innage tape is graduated to 1/8 inch, and the first whole
number on the tape is 9 or 10. Consequently, from the pointed tip of the conical bob to the first number
on the tape is 9 or 10 inches. From the tip of the bob to the top of the eyelet is 6.6 inches. The bob is
made of nonsparking metal, and "0" is at the bob's tip.
Figure 6-7. Innage tape and bob.
Outage Tape and Bob (Figure 6-8). The steel outage tape is similar to the innage tape except that the
readings begin at the 2-inch level. The "0" reference is where the harness snap connects to the bob.
The rectangular bob is 6 inches long, but the 1/8-inch graduations start with the 6-inch mark at the