Storage tanks inside a concrete bund wall
Storage tanks

Tank Farm Bund / Dyke

Foam makers on the bund wall for spill fire in the containment area.

Discuss this hazard

At a glance

Hazard family
Storage tanks
Protected by
Foam, Hydrant, Gas detection
Designed to
NFPA 11, OISD‑STD‑117, IS 13039
Foam application rate, fixed low-level outlets
4.1 L/min/m² of bund area

Design basis

Foam application rate, fixed low-level outlets
4.1 L/min/m² of bund areaNFPA 11 — diked areas
Foam application rate, monitors
6.5 L/min/m² of bund areaNFPA 11 — diked areas
Discharge time
20 minutes (flash point 37.8–93.3 °C); 30 minutes (below 37.8 °C)NFPA 11 — diked areas

Standards that apply

  • NFPA 11Low-, medium- and high-expansion foam.
  • OISD-STD-117Fire protection for petroleum depots and terminals.
  • IS 13039External hydrant systems — provision and maintenance.

The risk

A leak or an overfill runs into the bund. The bund keeps the liquid in — and with it the fire: a spill fire can cover the floor of the bund and put every tank standing in it at risk at once.

Before it ignites, an evaporating spill gives off a vapour cloud that drifts, and heavier vapours collect in low points and drains.

The scheme

Find the spill early, and blanket it before it burns or spreads:

  • Gas detection at the low points of the bund, where vapour collects.
  • Foam makers on the bund wall, or medium expansion generators, to blanket the spill and suppress the vapour.
  • Monitors and hydrants outside the bund wall, within reach of every part of it.
  • Cooling for the tanks standing in the bund.
Protection concept for a tank farm bund: detection, foam, cooling and hydrant layers

Systems that apply

Products used

Foam Equipment · 10

Spray Nozzles · 1

Questions we are asked

Why protect the bund as well as the tanks?

A spill fire in the bund exposes every tank standing in it at once. Foam on the bund floor puts it out before it spreads to them.

Where should gas detectors go in a bund?

At the low points and near drains, where vapour from a spill collects.

Foam makers or monitors?

Fixed foam makers on the bund wall respond without anyone approaching the fire; monitors are flexible and back them up. NFPA 11 sets a higher rate for monitors than for fixed outlets.

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