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Anhydrous Ammonia liquid weighs approximately 5 pounds
per gallon, at 60°F.
A pound of liquid Anhydrous
Ammonia will generate 22.5 SCF of ammonia vapor and
45 SCR of dissociated ammonia gas.
A storage tank is usually
considered to have an 85% usable capacity. (A 15%
vapor space must always be maintained when filling,
to allow for expansion).
Consult with our Sales
Department for further assistance with sizing a storage
tank and frequency of deliveries. Storage tanks are
available in a variety of sizes depending on individual
requirements.
Stationary storage tanks for anhydrous ammonia are
regulated by the U.S. Dept. of Labor and must conform
to the requirements of 29CFR1910.111. They are built
in accordance with the ASME Boiler and Pressure Vessel
Code and are rated for 250 psig.
Tanks should be located
in an area, preferably outdoors, where they will not
be exposed to damage by vehicular traffic, however,
access to within 50 feet is generally necessary for
tank truck delivery. The area should be clear of debris,
weeds or any combustible materials.
If the tank is located
where summer sun conditions are severe, provisions
should be made for sun shielding. In some area, local
codes require diking. Check your local codes.
Tanks should be mounted
on concrete, masonry or structural steel supports
and on firm concrete or masonry foundations. All foundations
should extend below the frost line.
Refer to ANSI
K 61.1 for additional information.
In the event of an emergency,
access to the tank must be provided. If the tank is
fenced in, two to four feet clearance is recommended
as a working area for maintenance purposes. Fenced
in tanks should also have two means of egress for
emergency escape.
All pipe and hose connections
to the tank are protected by excess flow valves to
prevent massive leakage in the event of a catastrophic
line break. Relatively high flows are required to
cause these valves to close so it should be noted
that a downstream break may not always result
in sufficient flow to close the valve.
Pressure gauge connections
and the 85% outage gauge are not protected by excess
flow valves but they do have a .054" restriction
to limit flow. Tank pressure gauges are also equipped
with isolating valves which can be closed off in the
event of a gauge failure.
The tank is equipped
with a dual safety relief valve system consisting
of two safety relief valves mounted on a three-way
valve. The design of the three-way valve permits shutting
off one or the other, but not both, of the relief
valves and allows replacement of either of the relief
valves without emptying the tank. Either relief valve
alone is sized to adequately protect the tank.
Different designs of
three-way valves have been used. The “Shank”
design has a handwheel. Facing the handwheel, to shut
off the right hand safety, turn the hand wheel counter
clockwise. To shut off the left hand safety, turn
the wheel clockwise. The handwheel should be left
in full counter-clockwise position so that the valve
stem packing and the right hand safety relief are
isolated from the tank pressure.
The “Frick”
or “Henry” design valves are of the “in-line”
type and may have a conical cap cover in the valve
stem. If the valve is of this type, the valve stem
has flats on it and a wrench must be used. Use caution
when removing the cap as it may be under a slight
pressure. Turning the valve stem clockwise will shut
off the safety relief furthest from the valve stem.
Turning the stem counter clockwise will shut off the
safety relief nearest the valve stem. The valve should
normally be left in the full counter clockwise position
so that the valve stem packing is isolated from the
tank pressure.
Tank content is determined
by means of a float gauge which reads in percent of
the total tank capacity. The gauge dial is usually
on the top of the tank; however, it may be located
at one end. When mounted on a 1,000 gallon tank and
reading 60%, the tank would contain 600 gallons. At
5 lbs. per gallon, this would be equivalent to 3,000
lbs.
Do not confuse this
gauge with the pressure gauge. The pressure gauge
would read the same whether there is a 200 gallons
in the tank or 800 gallons.
Storage and Handling of Anhydrous Ammonia
29 CFR 1910.111
Code of Federal Regulations, Title 29-Labor
Pamphlet
ANSI K61.1
Safety Requirements for the Storage & Handling
of Anhydrous Ammonia
American National Standard Institute
1430 Broadway
New York, NY 10018
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Notice:
We believe the information contained here to be accurate
and reliable; however, Tanner Industries, Inc. assumes
no liability or responsibility in connection with
the information or suggestions herein contained. Moreover,
it should not be assumed that every acceptable
test or safety procedure or method, precaution,
equipment or device is contained within, or that abnormal
or unusual circumstances may not warrant or suggest
further requirements or additional procedures.
The information
contained here should not be confused with federal,
state, municipal, or insurance requirements, or with
national safety or building codes, and no representations
or warranties are made with respect thereto.
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Sizing
Anhydrous Ammonia Storage Tanks