Which action is essential before connecting AFFF transfer hoses to a line?

• A. Fill the transfer line with water to prime.
• B. Inspect the pump seals for wear.
• C. Verify bonding/grounding with a strap and solid grounding point per SOP.
• D. Initiate transfer then test for ignition.

Answer: (C)

Static or floating charges can develop on hoses and lines during transfer of flammable foam concentrates, creating a real ignition risk from a spark. Establishing bonding and grounding before connecting AFFF transfer hoses provides a safe path for those charges to equalize with the earth, so any potential spark is prevented when the hoses are joined and moved. The bonding strap ties the equipment together to equalize electrical potential, and a solid grounding point gives that charge somewhere to go safely. This protective step is required by SOP because it directly reduces ignition hazards in the transfer area. Other actions don’t specifically address the ignition risk from static electricity, so they don’t fulfill the essential safety requirement in this moment.