Section 219.128  Monitoring VOL Operations

a)         Except as provided in subsection (d), the owner or operator of each storage vessel with a design capacity greater than or equal to 40,000 gallons storing a liquid with a maximum true vapor pressure that is normally less than 0.75 psia shall notify the Agency within 30 days when the maximum true vapor pressure of the liquid exceeds 0.75 psia.

b)         Available data on the storage temperature may be used to determine the maximum true vapor pressure.

1)         For vessels operated above or below ambient temperatures, the maximum true vapor pressure is calculated based upon the highest expected calendar-month average of the storage temperature.  For vessels operated at ambient temperatures, the maximum true vapor pressure is calculated based upon the maximum local monthly average ambient temperature as reported by the National Weather Service.

2)         For other liquids, the vapor pressure:

A)        Determined by ASTM Method D2879-83, incorporated by reference at Section 219.112(a)  of this Part;

B)        Measured by an appropriate method approved by the Agency and USEPA; or

C)        Calculated by an appropriate method approved by the Agency and USEPA.

c)         The owner or operator of each vessel storing a mixture of indeterminate or variable composition shall be subject to the following:

1)         Prior to the initial filling of the vessel, the maximum true vapor pressure for the range of anticipated liquid compositions to be stored will be determined using the methods described in subsection (b).

2)         For vessels in which the vapor pressure of the anticipated liquid composition is 0.5 psia or greater but less than 0.75 psia, an initial physical test of the vapor pressure is required; a physical test at least once every 6 months thereafter is required as determined by the following methods:

A)        ASTM Method D2879-83, incorporated by reference at Section 219.112(a) of this Part;

B)        ASTM Method D323-08, incorporated by reference at Section 219.112(a) of this Part; or

C)        As measured by an appropriate method approved by the Agency.

d)         The owner or operator of each vessel equipped with a closed vent system and control device meeting the specifications of Section 219.120 of this Subpart is exempt from the requirements of subsections (a) and (b).

(Source:  Amended at 37 Ill. Reg. 1722, effective January 28, 2013)