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Aqua ammonia is usually shipped in either cargo tanks,
polyethylene drums or composite drums. Aqua ammonia drums should
be stored out of the sun and away from heat. Drums
should not be subjected to rough handling or to abnormal
mechanical shock such as dropping or bumping. They
should be opened carefully to permit the venting of
any ammonia vapors which may have formed in the container.
Use a wrench with a long handle, stand to one side
and face away during the operation. Chemical safety
goggles, face shield, rubber aprons and gloves should
be worn. Allow accumulated pressure to vent before
removing plug completely.
Drums should be emptied
by gravity only. Use a faucet or safety siphon made
of material resistant to ammonia; no brass or bronze.
Application of pressure to the drum for unloading
is dangerous and should not be attempted.
Ammonia solutions in
water with concentrations between 10% and 35% have
a DOT hazard classification of 8 and are to be labeled
as Corrosive. Their identification number is UN2672
and are to be packaged in Group III containers. As
of October 1, 1996 when HM-181 became effective, all
Group III containers have to conform to UN specifications
and standards. These requirements are outlined in
CFR 173.24a(b)(4): Packaging tested as prescribed
in CFR 178.605 of this subchapter may be used for
liquids only when the vapor pressure of liquid conforms
to one of the following:
(b)(4)(i) The vapor
pressure must be such that the total pressure in
packaging (i.e. the vapor pressure of liquid plus
the partial pressure of air or other inert gases,
less 15 psi at 131¡F, determined on the basis of
maximum degree of filling in accordance with paragraph
(d) of this section) and a filling temperature of
59¡F, will not exceed two-thirds of the marked test
pressure, or
(b)(4)(ii) The vapor
pressure must be such that the total pressure in
packaging at 122¡F must be less than four-sevenths
of the sum of marked test pressure plus 15 psi,
or
(b)(4)(iii) The vapor
pressure must be such that the total pressure in
packaging at 131¡F must be less than two-thirds
of the sum of marked test pressure plus 15 psi.
Because the vapor pressure of aqua ammonia is about
equal to the atmospheric pressure, it must be stored
in closed containers.
The storage area should
be dry and cool. If housed in a closed building, ventilation
should be provided; either natural or mechanical.
Avoid pocketing of ammonia vapor under floors, roofs
or similar structures.
Remember, ammonia vapor
will burn when mixed in air at concentrations between
15% to 28%. Sparks or ignition sources must be excluded
wherever concentrations in this range could exist.
Carbon steel or stainless steel construction for the
tank is recommended. If other materials are used,
their compatibility with aqua ammonia should be verified
by the tank manufacturer. Tanks should have a 30 psi
pressure rating. They should be equipped with safety
relief valves rated for that pressure and they should
also be equipped with a vacuum breaker. Steel tanks
should be grounded. Other tanks constructed of different
material or with lower pressure ratings require careful
design. Please contact us for further assistance.
Deliveries to aqua ammonia storage tanks are made
by bulk transport of approximately 6,700 gallons.
A storage tank should be sized to hold at least one
and a half times this amount or about 10,000 gallons.
Transfer of material
from the cargo tank transport to the stationary storage
tank may be accomplished by various methods.
Compressor Method
Tanner Industries' tractors are equipped with PTO
powered compressors which can produce about 10 psig
differential pressure. Air or vapor pressure is used
to push the material out of the cargo tank into the
storage tank. Some provisions must be made to prevent
the buildup of pressure in storage tanks rated less
than 30 psi as they are being filled. This can be
done by permitting the compressor vapor to escape
to a scrubber system and also through the compressor
back to the cargo tank.
If a scrubber system
is used, it can be constructed using a properly labeled
water container. The vapors are introduced into the
water through a sparger to produce small bubbles for
easier absorption. Disposal of the weak aqua solution
produced may present a problem. Many of our customers
recycle the solution back into their storage tank.
If the vapor is fed
through the compressor back to the cargo tank, precautions
should be taken to insure that the storage tank is
not exposed to substantial vacuum. A vacuum on the
storage tank could result in its collapse or in a
reduction in strength of aqua ammonia which it contains.
To prevent the possibility of a vacuum occurring in
the storage tank, a supplementary vacuum breaker is
used. Our drivers are equipped with a special fitting
for this purpose.
Pump Method
The pump method is also used with the PTO shaft driving
the liquid pump. When using a pump, it should be kept
in mind that the vapor pressure of the aqua ammonia
is about equal to atmospheric pressure and that any
suction pressure will cause the ammonia vapor to come
out of solution and vapor lock will occur. Systems
should be designed so that the pump is as near to
the hose connection as possible and that the hose
length required will be as short as possible, twenty
feet or less.
Gravity Method
This method simply uses the force of gravity to move
product from the delivery unit to the receiving tank.
It usually only requires the use of one transfer hose
for liquid aqua ammonia. There is no vapor connection.
For this method of delivery, the storage tank would
have to be a lower level than the delivery unit.
Vapor lines should be sized at 1 or 1-1/4 inches and liquid
lines at 2 inches. Schedule 40 or 80 steel pipe and
malleable iron pipe fittings are acceptable. Do not
use galvanized pipe or fittings and make sure the
unions do not have brass seats. Make sure that other
fittings such as valves, pressure reliefs and back
checks are suitable for ammonia service. Plastic pipe
and fittings (with manufacturer's approval) may also
be used. Hose connectors need not be provided as Tanner
Industries' transports carry adapters to fit standard
pipe threads.
Unlike Anhydrous Ammonia, Ammonium Hydroxide storage
systems do not have to comply with any published regulatory
standards or specifications.
Therefore, it is imperative
that these systems are designed by qualified personnel
having prior experience with the product. Tanner Industries,
Inc. can assist you in designing or modifying your
system to operate in a safe, efficient and environmentally
responsible manner.
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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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