CFR > Title 46 - Shipping > CHAPTER I—COAST GUARD, DEPARTMENT OF HOMELAND SECURITY > SUBCHAPTER D—TANK VESSELS (parts 30 to 39) > PART 39—VAPOR CONTROL SYSTEMS > SUBPART 39.20—Design and Equipment (§39.20-1 to §39.20-13) > 39.20-13—High and low vapor pressure protection for tankships—T/ALL.

39.20-13—High and low vapor pressure protection for tankships—T/ALL.

Each tankship vapor collection system must be fitted with a pressure sensing device that senses the pressure in the main vapor collection line, which:
(a) Has a pressure indicator located on the vessel where the cargo transfer is controlled; and
(b) Has a high pressure and a low pressure alarm that:
(1) Is audible and visible on the vessel where cargo transfer is controlled;
(2) Alarms at a high pressure of not more than 90 percent of the lowest pressure relief valve setting in the cargo tank venting system; and
(3) Alarms at a low pressure of not less than four inches water gauge (0.144 psig) for an inerted tankship, or the lowest vacuum relief valve setting in the cargo tank venting system for a non-inerted tankship.