46CFR Part 39 Vapor Control Systems
Subpart 39.20 Design and Equipment
§ 39.20-7 Tankship liquid overfill protection -T/ALL (continued)

(3) Be identified with the legend "TANK OVERFILL ALARM" in black letters at least 50 millimeters (2 inches) high on a white background; and

(4) Alarm early enough to allow the person in charge of transfer operations to stop the transfer operation before the cargo tank overflows.

(e) If a spill valve is installed on a cargo tank fitted with a vapor collection system, it must meet the requirements of Sec. 39.20-9(c) of this part.

(f) If a rupture disk is installed on a cargo tank fitted with a vapor collection system, it must meet the requirements of Sec. 39.20-9 (d) of this part.

39.20-9 Tank barge liquid overfill protection-B/ALL

Each cargo tank of a tank barge must have one the following liquid overfill protection arrangements.

(a) A system meeting the requirements of 39.20-7 of this part which:

(1) Includes a self-contained power supply;

"The APM-2 Annunciator Panel connected to ERL Liquid Level Sensors satisfy this requirement."

(2) Is powered by generators installed on the barge; or

(3) Receives power from a facility and is fitted with a shore tie cable and a 120 volt 20 amp explosion- proof plug which meets:

(i) ANSI/NEMA WD6;

(ii) NFPA 70, Articles 410-57 and 501-12; and

(iii) 111.105-9 of this chapter.

(b) An intrinsically safe overfill control system which:

"ERL Liquid Level Sensors satisfy this requirement."

(1) Is independent of the cargo gauging device required, by 39.20-3(a) of this part;

(2) Actuates an alarm and automatic shutdown system at the facility overfill control panel, or on the vessel to be lightered if a lightering operation, 60 seconds before the tank becomes 100 % liquid full;

(3) Is able to be checked at the tank for proper operation prior to each loading;