NVIC 11-82: Deck foam systems for polar solvents

NVIC 11-82 21 May 1982 NAVIGATION AND VESSEL INSPECTION CIRCULAR NO. 11-82 Electronic Version for Distribution Via the World Wide Web Subj: Deck Foam Systems for Polar Solvents

Deck Foam Systems for Polar Solvents — PURPOSE. The purpose of this Circular is to provide guidance for the design and review of deck

foam firefighting systems for tank vessels carrying polar solvents. 2 BACKGROUND. Regulations 46 CFR 34.20-5(b)(2) and 46 CFR 153.460 require that tank vessels which carry polar solvents be equipped with foam systems whose application rate depends upon the vessel design, the products carried, and the foam system. Polar solvents are water miscible products such as alcohol and ketones which attack regular firefighting foam. Therefore, special "polar solvent foams" have been developed for these products. These special foams are also known as “alcohol foams” and in the IMCO Chemical Code* and Part 153 of Title 46 CFR, Systems using these foams are identified as type "A" fire protection systems. Unlike regular foams that are applied at the same rate on all hydrocarbons, the application rates necessary for polar solvent foams vary with the quality and type of foam concentrate, the characteristics of the polar solvent product, the arrangement of the hazard, and the method of application. This Circular outlines two procedures for determining acceptable application rates. *Code for the Construction and Equipment of Ships Carrying Dangerous Chemicals in Bulk, Resolution A.212, 1980 Edition incorporating amendments 1 to 9, Intergovernmental Maritime Consultative Organization, 3. DISCUSSION. a. If a tanker carries only regular hydrocarbons (i.e. no polar solvents), a foam system with a nominal foam application rate of 0.16 gallons per minute per square foot of protected area is adequate. The rates for designing such a shipboard system are contained in 46 CFR 34.20-5(b)(1) and 34.20-25 and are summarized in enclosure (1) of this Circular. Unfortunately different polar solvent products require different minimum foam application rates as a basis for design. Two alternatives are now being used by the Coast Guard to evaluate flow rates of foam systems protecting polar solvent products.

(1) Method 1. This method involves either restriction of the products carried or their locations aboard a vessel. Vessels using this method are considered to be dedicated

(i.e. restricted) to the carriage of specific cargos and the Certificate of Inspection is endorsed to limit the vessel or a portion of the vessel based upon the capacity of the polar solvent foam system. As part of the Coast Guard polar solvent foam system approval procedure, foams are tested on various polar solvents to determine the minimum application rate for each product. Foam manufacturer’s design manuals are now being approved with appendices listing minimum application rates for specific products. Enclosure (4) illustrates an example in which a manufacturer has grouped products into three appendices each requiring a different minimum application rate with his foam. Calculations similar to those used for regular hydrocarbons have been developed and are shown in enclosure

(2). Since the IMCO Chemical Code allows alternative designs for "ships which are dedicated to the carriage of specific cargos", chemical carriers can take advantage of the lower foam rates using this method and still be issued a Certificate of Fitness. Enclosure (5) is an example in which this method results in a lower foam rate.

(2) Method 2. This method is described in the ninth set of amendments to the IMCO Chemical Code. Method 2 is acceptable for tankers that carry polar solvent products as well as for tankers that carry polar solvent chemicals. Except for systems installed prior to 1975 which used less efficient foam concentrates, no cargo or loading restrictions related to the foam system are necessary for vessels with foam systems meeting these rates. The application rates are summarized in enclosure (3). b. If the dedicated cargo calculations, Method 1, are used, the tanker's Certificate of Inspection is endorsed to reflect the limitations imposed because of the foam system.. To avoid a duplicate listing of all possible cargos on the certificate, the foam manufacturer’s design manual may be cited and copies of the appropriate pages kept aboard. Typical certificate entries are:

(1) "Because of the foam system design, this vessel is dedicated to the polar solvents listed in Appendices A and B of XYZ Foam Co. approved Design Manual 00. Other flammable and combustible polar solvents shall not be carried".

(2) "For the purpose of the polar solvent foam system, the vessel is dedicated to the cargos listed in Appendices A, B and C of XYZ Foam Co. Design Manual 00 as follows: Appendix A cargos: all tanks. Appendix B cargos: wing tanks only Appendix C cargos: number 1 port and starboard only". c. If a shipper wishes to add new polar solvent cargos, the foam system manufacturer's lists may be expanded by contacting the manufacturer directly and submitting samples for testing. The foam system manufacturer then makes the appropriate submittal to the Coast Guard and after verification the Coast Guard approves the revised lists. The Certificate of Inspection may have to be revised in some cases. d. After the designer determines the foam system application rate using one of the above methods) he should refer to 46 CFR 34.20 for additional foam system design requirements. 46 CFR 153.460 and section 3.14 of the IMCO Chemical Code should also be consulted for additional requirements for chemical carriers which are to be issued a Certificate of Fitness. 4. ACTION. New polar solvent foam systems are acceptable under 46 CFR 34.20 and 46 CFR 153.460 if designed to supply foam solution at either of the rates determined from the criteria in paragraph 3.a. of this Circular. There is no need to recalculate previously approved foam installations. However owner/operators may do so if recalculation would be to their advantage. Recalculations should be resubmitted through the foam system manufacturer. Encl: (1) Calculation of Regular Foam Systems

(2) Calculation of Polar Solvent Foam systems Dedicated to Listed Cargos method 1)

(3) Calculation of Polar Solvent Foam Systems Using Method Z'

(4) Typical Appendix Lists from Foam System Approval

(5) Example Foam Rate Calculation NON-STANDARD DISTRIBUTION: Ce: Baltimore (75); Boston, San Francisco, Mobile, Pittsburgh, Providence, Norfolk (50); Galveston

(30); Cleveland, Portland OR, Sturgeon bay (25); San Diego, Savannah, Buffalo, Corpus Christi

(20); Tampa, Valdez, Milwaukee, Louisville, Detroit, Toledo, Nashville, Anchorage (15); Portland ME, Duluth, Charleston, Huntington, Miami, Minneapolis-St. Paul (Dubuque), San Juan (10); Juneau, Cincinnati Memphis, Wilmington, Paducah (5) extra Cm: New Orleans (250); New York (200); Seattle (100); Houston (50); Terminal Is (LA-LB), Philadelphia (40) extra Em: New London, Houma (30); Ludington (8) extra En: Ketchikan, Kenai, Kodiak, Lake Charles (5) extra List CG-12, ZTC-68