Offshore helidecks - testing of helideck foam production systems

Introduction

1. This notice is to remind dutyholders of the need to ensure that the annual testing of the quality of offshore helideck firefighting foam concentrates and mixing/induction systems are fit for purpose and has been produced in conjunction with the Civil Aviation Authority (CAA).

Background

2. On 1 December 1998, the CAA delegated responsibility for offshore helideck authorisations to the British Helicopter Advisory Board (BHAB) Helideck Sub-Committee. Since then there have been an increasing number of instances where produced foam samples sent to recognised test houses by dutyholders have apparently fallen outside the boundaries of tolerance stated in test procedures but have nonetheless been 'passed' on the testing house's certificates and accepted by dutyholders. 'Fail' test results have been especially common amongst finished foam samples taken from 1% induction foam systems. A foam solution that is too lean will not be as effective in extinguishing or controlling the fire on a helideck and in an extreme case may not extinguish the fire at all. This would significantly increase the risks for passengers on board a burning helicopter.

3. Civil Aviation Publication CAP 168, Licensing of aerodromes, Chapter 8, Appendix 8E, paragraph 1.4.2 states that the CAA does not approve, inspect or certify firefighting equipment or material, nor does it approve or evaluate testing laboratories.

Action

4. Dutyholders should:

• review their existing management systems and test procedures against CAP 437 (Chapter 5, Helideck rescue and Firefighting facilities, paragraph 5.3.3), UKOOA Guidelines for the management of offshore helideck operations (Section 12, Firefighting and safety equipment, Part 4), together with the Annex to this notice;
• ensure that these reflect the guidance on assessing the fitness for purpose of the mixing/induction system and the quality testing of foam concentrates;
• advise the relevant test house of any changes made, and draw their attention to the content of this notice.

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Relevant legal requirements

5. Offshore Installations (Prevention of Fire and Explosion, and Emergency Response) Regulations 1995, regulation 7 - equipment for helicopter emergencies, and regulation 19 - suitability and condition of plant.

References

Civil Aviation Authority (CAA) CAP 437 Offshore helicopter landing areas: Guidance on standards Fourth edition (September 2002) ISBN 0 86039 741 6

UKOOA Guidelines for the management of offshore helideck operations Issue 4 (February 2003)

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Further information

Any queries relating to this notice should be addressed to:

Health and Safety Executive
Hazardous Installations Directorate
Offshore Division
Lord Cullen House
Fraser Place
Aberdeen
AB53 4AP

Tel: 01224 252500
Fax: 01224 252629

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Annex

Testing procedures for foam samples

1. In general terms there are two foam test procedures, one based on British Standard 5306 and the other on the US National Fire Protection Requirement (NFPA) 11. The selection of the appropriate test procedure will depend on the original design specifications of the foam system. This annex sets out procedures for foam test analysis from collection through to certification of foam samples and is intended to assist foam test houses, dutyholders, helicopter operators and helideck inspectors, so that each may reasonably discharge their duty of care.
2. The foam that is applied to the helideck is a mixture of foam concentrate and water. In order to operate at optimum efficiency the foam concentrate should be of an acceptable quality and the mixing/induction system used must ensure that the concentrate and water are mixed at the correct ratio.
3. In order to assess the quality of the foam system the following samples should be sent to the laboratory for analysis from each inducting system:
   • 1.0 litre of foam concentrate
   • 0.5 litre of produced foam
   • 1.0 litre of seawater
4. When completed, the test certificate should make it clear which standard has been used for testing (BS 5306 or NFPA 11) and be clearly marked 'Passed' or 'Failed'.
5. Testing of foam concentrate should include inspecting a range of physical properties such as specific gravity, surface tension and appearance to identify the category of foam and indicate if any contamination has occurred. Expansion and drainage tests should assess the properties of aerated foam and specialised tests, such as alcohol burnback for alcohol resistant foams and petrol tolerance for fluoroprotein foams, give a comprehensive assessment of the quality of the foam concentrate.
6. A one litre sample of foam concentrate in a clean polythene container is required. If new, unused, containers are unavailable, ensure that the containers used are washed properly beforehand. Do not use containers that have previously contained detergent or oil materials.
7. Samples of foam concentrate should be representative of the parent stock. A foam drum should be rolled or agitated to produce a homogeneous mix before drawing a sample from the top. For bulk foam storage tanks circulate the contents to produce a homogeneous mix before taking a sample. Alternatively draw samples from the top, middle and base. Use a hollow tube to take a sample from the middle. For the base sample use a side-exiting outlet pipe or alternatively run-off about 25 litres of foam first to remove any accumulated sediment. This run-off may be returned to the top of the tank. Several samples may be mixed equally to produce a single composite sample.
8. Samples should be clearly labelled with origin, foam type, and recommended induction rate. All samples should be packed securely with a completed foam testing service application form and sent to the testing agency.
9. The produced foam test determines the accuracy of a foam system's proportioning equipment by measuring the percentage concentration of a foam concentrate in the foam solution. The amount of foam concentrate in the solution is measured with a refractometer. A base curve is first drawn using the sample of foam concentrate and water taken from the foam system. Samples of the actual foam solution produced by the system are then tested and plotted on the graph to find the concentration.
10. Activate the fixed foam system and allow sufficient time for it to achieve equilibrium. For overhead devices the sample collector should be placed in the discharge area where it is anticipated a representative foam pattern will occur. For foam chambers, where access can be gained to a flowing foam stream, the container can be inserted into the edge of the stream to split off a portion for the sample. The other alternative is to scoop foam from a blanket already on the surface. Here an attempt should be made to obtain a full cross-section of foam from the entire depth. Sufficient aerated foam should be collected to provide a 500 ml sample of foam solution after draining. Clearly labelled one litre samples of the foam concentrate and water used in the foam system must also be submitted.
11. Samples should be clearly labelled with origin (installation name, appliance number, etc). All samples should be packed securely with a completed foam testing service application form and sent to the testing agency.

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