Tapes are the same as the image tapes except that the zero point on the outage tape is at the swivel hook. Used for outage measurement. Marked in feet, inches, and ⅛ths.
When using outage gauging tapes, the tape is lowered into the tank until the plumb bob just penetrates the liquid. The tape is then read at the reference point on the tank. The tape is rewound and the liquid level is read directly from the plumb bob. The reading on the plumb bob is off fed to the tape reading giving the total outage gauge.
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