The Use of Pressurized Liquid Dispensing Containers (PLDCs) With Flammable Liquids in Laboratories

Large quantities of flammable solvents are used in today’s high-throughput analytical and biopharmaceutical laboratories. To minimize hazards, these laboratories have tried to adopt alternative containers that are safer than glass bottles. Typically these safer containers are constructed of stainless steel, designed for pressure dispensing, and are between 20 and 208 L in size (see Figure 1). Laboratories have been restricted from using these containers for flammable liquids because they were not defined in NFPA (National Fire Protection Association) 45, the Standard on Fire Protection for Laboratories Using Chemicals.

Figure 1 - Typical 200-L stainless steel container designed for pressure dispensing solvents.

The 2000 Edition of NFPA 45 Table 7.2.3.2, Maximum Allowable Container Capacity, restricted flammable liquid containers to 20 L or less (see Figure 2). In order to use larger containers in laboratories, it was necessary to use a section of the standard labeled “Equivalency.” This section is stated as follows:

1.1.4 Equivalency
Nothing in this standard is intended to prevent the use of systems, methods, or devices of equivalent or superior quality, strength, fire resistance, effectiveness, durability, and safety over those prescribed by this standard. Technical documentation shall be submitted to the authority having jurisdiction to demonstrate equivalency. The system, method, or device shall be approved for the intended purpose by the authority having jurisdiction.

Figure 2 - NFPA 45 Table 7.2.3.2, Maximum Allowable Container Capacity.

Some laboratories citing this section were allowed by the “authority having jurisdiction,” usually the local fire marshal, to use containers larger than 20 L. Other laboratories were denied because the larger containers were not specifically allowed in the Maximum Allowable Container Capacity table. A consortium of companies that were being denied use of these containers approached the NFPA to learn what was required to have the containers written into the 45 Standard. According to the NFPA 45 Committee, they would need to see data from actual testing of the containers in a fire situation. In response, a Technical Advisory Committee was formed with representatives from the following companies to develop a test program:

  • Aventis (Strasbourg, France)
  • Bristol-Myers Squibb Co. (New York, NY)
  • Eli Lilly and Co. (Indianapolis, IN)
  • EMD Chemicals, Inc. (Gibbstown, NJ)
  • Fisher Scientific (Pittsburgh, PA)
  • Honeywell Burdick & Jackson (Muskegon, MI)
  • Merck & Co. Inc. (Whitehouse Station, NJ)
  • SmithKline-Beecham (Middlesex, U.K.)
  • Schering-Plough Corp. (Kenilworth, NJ).

The test program (see Figure 3) was operated by the Fire Protection Research Foundation (FPRF), an independent nonprofit organization associated with the NFPA. The FPRF’s mission is to provide practical, usable data on fire and building safety. Program testing was performed by a nationally recognized research and development laboratory using hexane-filled containers, with nominal 55-gal (208-L) capacity, to simulate realistic fire situations.

Figure 3 Preparation for fire testing.

Figure 4 - Fire testing in progress.

The test protocol was to expose three different container designs to both stored, no hoses connected to the containers, and in-use conditions; the containers had both a gas pressurization hose and a solvent dispense hose connected to them. The fire conditions included both a spray fire, which involved four nozzles spraying flaming hexane at the containers so that they were engulfed in a ball of fire, and a pool fire, in which containers were placed in a contained pool of 5 or 10 gal of hexane that was then ignited (see Figure 4). Some of the tests also included an activated sprinkler system to simulate a typical laboratory sprinkler system. Data collected during the tests included container pressure, water pressure of the sprinkler system, fuel delivery pressure, fire temperature, and photographic/video. The performance of the containers was documented (see Figure 5) and compared to hexane-filled 4-L glass bottles. This included both plain glass bottles and plastic-coated (shatter-resistant) bottles, the current standards for high-purity flammable liquids in laboratories (see Figure 6).

Figure 5 - Container after testing.

Figure 6 - Four-liter bottle testing: a) before, b) during, and c) after.



The project test data were analyzed, and it was found that no stainless steel container exceeded its design pressure because the pressure relief devices performed as expected. All of the bottles broke in less than 1 min 20 sec. The technical documentation was given to the NFPA 45 Committee for review. As a result, the 2004 Edition of NFPA 45 was modified to include:

  • Definition of the pressurizable containers designed to contain flammable liquids as PLDCs
  • Volume for flammable liquids was increased to 227 L (see Figure 7)
  • Conditions for using PLDCs.

NFPA 45 2004 Edition
PLDC Definition
3.3.50 Pressurized Liquid Dispensing Container (PLDC). DOT, UN 1A1, or ASME pressure container designed to dispense flammable or combustible liquids by gas pressure.

10.4 Pressurized Liquid Dispensing Containers.
10.4.1 Pressurized liquid dispensing containers used for flammable and combustible liquids shall be listed or labeled for their intended use by a nationally recognized testing laboratory.
10.4.2 Non-metallic containers larger than 4 L (1 gal) shall not be used.
10.4.3 Relief devices shall discharge to a safe location, in accordance with the manufacturer’s recommendation.
10.4.4 The piping/hose between the container and the use point shall be rated for the pressure, compatible with the materials being transferred and not subject to mechanical damage.
10.4.5 Prior to pressurizing the system, all fittings and connections shall be secure and leak free.
10.4.6 A readily accessible means to stop the flow of liquid from the container shall be provided.
10.4.7 Containers shall be pressurized only with nitrogen or inert gas; air shall not be used.
10.4.8 A means to prevent backflow into the gas supply system shall be provided.

Figure 7 - Modified NFPA 45 table.

Conclusion

NFPA standards did not specifically allow for the use of pressurized liquid dispensing containers holding volumes of flammable solvent exceeding 20 L. Absent explicit authorization, many local authorities did not permit laboratories to use PLDCs, depriving companies of both a safer and more efficient alternative to traditional glass bottles. A Technical Advisory Committee, representing key industry stakeholders, was formed to document the safety benefits of PLDCs and to petition the NFPA to amend NFPA Standard 45.

Based on the work of the Committee, NFPA 45 was amended in 2004 to specifically allow for PLDCs containing volumes of flammable solvent greater than 20 L. This amendment effectively gave regulatory personnel; laboratory directors; insurance representatives; and health, safety, and environmental (HS&E) departments a nationally recognized standard to use when making the decision as to whether PLDCs should be allowed in a laboratory. Laboratories located in most municipalities in the United States now have access to this safer and more efficient packaging alternative.

Mr. Westra is Technical Service Chemist, Honeywell Burdick & Jackson, 1953 S. Harvey St., Muskegon, MI 49437, U.S.A.; tel.: 231-725-6262; fax: 231-728-8226; e-mail: jim.westra@honeywell.com. All statements, information, and data given herein are believed to be accurate and reliable but are presented without guaranty, warranty, or responsibility of any kind, expressed or implied. Statements or suggestions concerning possible use of products or formulations are made without representation or warranty that any such use is free of patent infringement and are not recommendations to infringe any patent. The user should not assume that all safety measures are indicated or that other measures may not be required. All figures and tables reproduced with permission from the Fire Protection Research Foundation.

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