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Container Regulations

 


 

ISO 9001:2000
Registered Firm

Pressure Dispensing Solvent Containers

1. Current Solvent Container Regulatory Considerations
2. Positive Pressure Containers and Pressure Vessel Definitions
3. Safety Practices Associated with Pressurized Returnable Solvent Containers
4. The PTI-20 Returnable Solvent Cylinder

1. Current Solvent Container Regulatory Considerations
This Overview is far from complete. As far as we know there is no one source that can be looked at in order to get a complete overview of what is called the "limiting regulation". Every state and jurisdiction or location does have a "limiting regulation" defined as the fire code, building code or even company wide policy that defines the maximum flammable solvent that can be handled or stored at that location. PTI is attempting to collect that data - first in a state by state view and then in "specific zones" view. We plan to share any data received with those people who participate in the survey and work on the collection of that data.

OSHA
The use of large solvent containers in the workplace is allowed by OSHA regulation 1910.106. This regulation allows metal containers up to 60 gallons for Class 1A, 1B and 1C liquids. OSHA's code and quantities are in fact what was listed in NFPA 30 in 1967 when that part of the OSHA code was written.

NFPA (National Fire Protection Association)
A number of states have either directly "incorporated by reference" some of the NFPA codes or done so indirectly by incorporating an NFPA code which has made another NFPA code a part of its requirement to comply. It should also be noted that a number of US government agency's have made incorporation of specific NFPA codes mandatory at specific locations or have even mandated agency wide compliance.

The two most relevant NFPA (National Fire Protection Association) codes for the use of flammable liquids ar NFPA 30, Flammable and Combustible Liquids Code and NFPA 45, Fire Protection for Laboratories Using Chemicals.

For laboratory use, NFPA 45 can limit flammable liquid containers to 4 Liters for glass bottles and 5 gallons for metal containers (non pressure vessel). Formulas involving room size and solvent storage cabinets are required for storing quantities exceeding these limits. Large quantity solvent storage is allowed in specially constructed rooms under NFPA 30.

NFPA 30 also allows solvents to be piped to the point of use, providing that shut off valves are available at the container and at the point of use. However NFPA 45 does not currently address piping flammable liquids from such locations. NFPA 45’s paragraph 8-2 includes standards that address piping flammable gases, however those definitions do not currently include pressurized flammable solvents.

Western Fire Code (WFC)
Jurisdictions in states recognizing the WFC - and often individual cites within a state that does not itself recognize the WFC - have adopted all or parts of the WFC as their basic fire code. Most jurisdictions that recognize and use the Western Building Code also mandate the Western Fire Code. In the past companies that operate in the East – and which sell to companies in the West have had difficulty getting- a clear picture of what the Western Fire Codes require as to quantities of flammable liquids in either laboratories or pilot plant operations. NFPA codes are of no use here.

All states have incorporated one of the national building codes such as WBC (Western Building Code), BOCA (Building Official Code Administrators, Int.), SBCC (Southern Building Code Congress, Int.). The maximum amount of flammable solvents is addressed by these codes. The question then is if they take precedence or prescribe i.e. allow another code or standard to take precedence in specific instances such as “a laboratory”.

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2. Positive Pressure Containers and Pressure Vessel Definitions

Positive Pressure Dispensing Container: A Pressure Dispensing Container (PPDC) is a non-bulk vessel or cylinder which uses a compressed gas as a propellant to discharge a liquid from the vessel. The propellant gas may be adde3d prior to or during the discharge of the liquid. Normally the compressed gas used as the propellant is neither flammable or reactant.

Pressure vessels: Today, even as companies introduce smaller than 20 liter units, most returnable solvent containers are designed for positive pressure dispensing. Pressure dispensing introduces additional regulatory considerations.The three types of positive pressure containers now in the market are UN1A1/UN1A2, ASME or DOT.

UN1A1/UN1A2
The UN1A1/UN1A2 container is built to UN performance test specifications, which are accepted by DOT (US Department of Transportation), TC (Transport Canada) and most of the countries of the world. However, UN 1A1/2 containers are not pressure vessels which means they are not legal for shipping with pressures over 25 psig*. (*Flammable materials as defined in 49 CFR as Division 2.1 (Flammable Gas) are addressed by the DOT during transportation even if they do not meet the pressure criteria of a “compressed gas”).

Some UN1A1 containers are marked with pressure ratings exceeding 25 psig. However, by DOT regulation these ratings are only to control the vapor pressure developed by the liquid in the container. Only DOT specification or DOT exemption containers may be shipped under pressure in the United States. NFPA codes (NFPA 45 (1966 Edition) 8-1.3) require a pressure vessel for pressures over 15 psig. Many states – such as required by California OSHA - have statewide requirements that any pressure vessel must meet requirements of their "unfired boilers and pressure vessel" codes. Pressure vessels are, in most jurisdictions, either DOT (US Department of Transportation) or ASME containers.

ASME (American Society of Mechanical Engineers)
ASME containers are certified as pressure vessels by meeting strict ASME codes for the particular pressure rating marked on the container. NFPA 30 also addresses on-site pressure tanks which must meet ASME code. A container "made to ASME" specifications but not marked with an ASME registered symbol is not an ASME pressure vessel.

Note again that ASME containers are not allowed for shipping of pressurized materials by the US DOT or Transport Canada. Therefore, ASME containers cannot be shipped with more than 25 psig pressure - although they can be used up to their rated pressure at the user’s location.

DOT
DOT pressure vessels (the most common are gas cylinders) are built to DOT specifications (or an approved exemption to a listed specification) for a rated pressure. DOT cylinders may be legally shipped and used at pressures up to their rated pressure. The pressure at 70O F (called the service pressure) is the maximum pressure a cylinder can be filled to or shipped at. The shipment of flammable solvents in DOT pressure vessels is allowed by 49CFR, paragraphs 173.101, 173.201-203 and 173.305 .

The NFPA allows the use of DOT pressure vessels. DOT cylinders have been used for decades in all 50 states with non-flammable (Division 2.2), flammable (Division 2.1) and poisonous (Division 2.3) materials.

In a proposed revision to NFPA 45, the maximum size of cylinders allowed in laboratories may be changed to be consistent with DOT regulations. DOT, flammable liquid cylinders may be up to 100 pound water capacity (about 45 liters).

Some companies market containers that are Factory Mutual (FM) approved. The FM approval is not recognized in current pressure vessel codes. In fact, in our experience, FM approval guidelines are much less strict than ASME or DOT pressure vessel codes. The FM approval should not be considered a substitute for these proven and mandatory codes.

FM approval may have merit for any electronic volume sensors that may be used on the containers.

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3. Safety Practices Associated with a (Returnable) Pressure Dispensing Container (PPDC)

The concept of positive pressure solvent dispensing has raised safety questions in the minds of some people. Concerns about pressurized liquids are tempered by the fact that the safe piping and dispensing of compressed gases from cylinders is an everyday practice in hundreds of thousands of laboratories. In fact, DOT flammable gas cylinders have been used in laboratories for almost 100 years. We believe the concepts used for compressed gas dispensing will also provide safe solvent dispensing.

Strong, essentially unbreakable containers can be placed in labs, solvent cabinets or in cylinder storage areas. Solvents are dispensed through stainless steel piping to the point of use. Valves and regulators provide safe flow control and shut off just as with compressed gases.

One must always also consider the current problems with solvent bottles in laboratories. Is having a person pouring a four liter bottle of a flammable solvent into an instrument reservoir (often higher than their heads) a safe procedure when judged against the hazard analysis hurdle often brought out to judge a PPDC. Safe handling and storage requires good housekeeping practices to be compliant with NFPA requirements. Some labs exceed recommended storage limits by storing cases of solvents far exceeding allowable limits and we have even seen the use of pressure to dispense from bottles or plain solvent cans. The use of containers that are not pressure vessels is both unsafe and illegal.

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4. The PTI-20 Returnable Solvent Cylinder

The Purification Technologies PTI-20 is called a cylinder because it is the only returnable solvent container which is built of 316 stainless steel to DOT pressure vessel specifications. We selected a DOT pressure vessel because the unit can be shipped and returned with pressure. (Remember if the customer does not properly vent a non-DOT container, they are the “shipper of record” and therefore liable for fines that can run into the thousands of dollars.)

Use of DOT cylinders also allows the solvent filler to pre-pressurize the container for dispensing and for the customer to return with residual pressure if necessary. Possible fines are eliminated which can happen when shipping a pressurized UN1A1 or ASME container.

The PTI-20 can be used to dispense solvents from cylinder storage areas. The PTI-20 may also be used to dispense solvents from within laboratory areas although it should be in a solvent cabinet. This restriction may be eased with the revision of NFPA 45.

Purification Technologies does not recommend UN1A1 containers for pressure dispensing unless they also meet ASME specifications. Since UN1A1 containers are not approved pressure vessels, there are potential safety and liability problems when used with positive pressure. A “tested to” pressure does not mean “rated for” pressure.

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