MIL-HDBK-1022A
Table 2
APPURTENANCES
Item
Appurtenance
V-A
H-A
H-U
C-E
V-U
k
Open atmospheric vents with weather hoods and
bird screens for tanks to be used for products
with true vapor pressure of 0.75 psia (5 kPa)
or less. For higher vapor pressure, or if a
vapor recovery system is used, provide
pressure/vacuum vents in lieu of open vents.
Consider using pressure/vacuum vents if
product quality is at risk by blowing sand,
dust, or snow. Comply with NFPA 30, host
nation requirements, Section 2 of this
handbook, API Std 650, API Std 2000, 29 CFR
Part 1910.106, and Standard Design AW 78-24-
27, where applicable. Do not use flame
arrestors.
l
Emergency relief venting with capacity in
accordance with NFPA 30 and UL 142, as
applicable. For vertical aboveground tanks, a
weakened roof-to-shell seam, as specified in
API Std 650, may be used to fulfill emergency
relief requirements.
*NOTE: Because horizontal tanks will fill extremely fast in t he last 5 percent,
values of high level alarm positions should be chosen based on filling rate, tank
size, and time needed.
Gauge/Gauge Hatch/Stilling Wells
m
A liquid level gauge calibrated in 1/16-inch
(2 mm) graduations mounted for eye-level
reading from the ground.
LEGEND:
142
V-A
=
Vertical Aboveground Storage Tank
H-A
=
Horizontal Aboveground Storage Tank
H-U
=
Horizontal Underground Storage Tank
C-E
=
Aboveground Concrete-Encased Storage Tank
V-U
=
Vertical Underground Storage Tank
Previous Page
