Cold Storage Warehouse Fire Protection — Dry and Pre-Action Systems, Ice Plugs, Panels

A cold store is one of the hardest environments in sprinkler engineering. Sub-zero temperatures rule out wet systems, while dry and pre-action systems bring their own problems: ice plugs, delayed water delivery and larger design areas. On top of that, the building itself (insulated sandwich panels) and the refrigeration plant (ammonia or other refrigerants) are separate sources of risk.

Hazard classification: NFPA 13 and EN 12845

For classification purposes a cold store is a storage facility: protection criteria follow commodity, packaging, pallets and storage height. Frozen food may burn poorly, but cartons, plastic film, foam packaging and timber or plastic pallets make up the fire load.

For a first classification use the NFPA 13 hazard classification tool and the EN 12845 hazard class finder.

System selection

Dry pipe

• Pipework is charged with compressed air or nitrogen; when a head opens, the dry pipe valve trips and water enters the pipe.
• Because water takes time to reach the most remote head, the standards limit water delivery time and enlarge the design area (NFPA 13 increases the dry system design area by 30%; EN 12845 also enlarges the area of operation for dry installations — confirm the factor in the current edition).
• More detail: EN 12845 dry pipe installations.

Pre-action

• Freezers often use double-interlock pre-action: water enters only when there is both a detection signal and a loss of pipe pressure. This stops the pipework filling and freezing after mechanical damage.
• The price is a delay until both conditions are met; design area and water delivery time are assessed accordingly. See pre-action sprinklers.

Storage sprinklers and ESFR

ESFR heads are generally listed for wet systems only. Freezers therefore use specially approved storage sprinklers suitable for dry or pre-action systems, or control-mode solutions combined with in-rack protection. Options for unheated areas: ESFR and CMSA in unheated areas.

Antifreeze

Antifreeze systems remain an option for small volumes, but current NFPA 13 editions accept only listed antifreeze solutions in new systems, and EN 12845 limits antifreeze to small subsidiary installations. In food stores the solution type also has to be assessed for hygiene.

Ice plugs and pipe details

Most cold store sprinkler failures come from ice plugs: moist air from the warm side enters the pipe, freezes on the cold side and blocks it.

• System air must be as dry as the freezer itself; use a compressor with a dryer or a nitrogen generator.
• Arrange the pipe at the freezer entry with a removable inspection section; apply the detailed requirements of the current edition of the standard.
• Low points and drains belong on the warm side; no water may remain in the pipe after testing.
• Frost protection strategies: EN 12845 frost protection; typical defects: freeze damage in sprinkler systems.

Building fabric: sandwich panels

Cold stores are usually built from foam-cored insulated panels. With a combustible core, fire travels inside the panel, hidden from sprinkler water. Where possible, choose non-combustible cores or panels with insurer-accepted test performance, and deal separately with the void above panel ceilings and penetrations between plant room and store.

Water supply and pumps

• The governing scenario is usually the freezer store; the dry system area increase pushes demand up.
• Tank volume: fire water tank sizing; duration per the storage criteria.
• Heating of outdoor tanks and pipework: FM DS 3-2 tank heating.
• Pump room heating and diesel fuel: diesel fire pump fuel tank calculator.

Detection, alarm and refrigeration interface

• Aspirating smoke detection (ASD): sampling pipes in the freezer with the detector unit on the warm side. It can also serve as the release signal for the pre-action system.
• Heat detectors: point detectors may fall outside their listing at low temperatures; select products for the temperature class.
• Ammonia: ammonia detection, emergency ventilation and power isolation logic in the plant room; the state of the refrigeration system during a fire must be documented. See cold storage and ammonia.
• Smoke ventilation: smoke clearance is difficult in a sealed, insulated building; assess mechanical extract or openable vents for fire brigade use: smoke vent area calculator.

Turkey: points under the BYKHY

The BYKHY links sprinkler requirements for storage buildings to hazard class and compartment area. Cold stores are often large single compartments, so compartment size and the details of separating walls should be settled early.

• Buildings requiring sprinklers in Turkey
• Which standard applies
• Hose reels and hydrants (wet hose reels cannot be used inside freezers; use dry risers or external positions)

Common site mistakes

1. Moist system air. The compressor draws humid air from the warm side and ice plugs form.
2. Water left in the pipe after testing. A dry system that is not fully drained freezes.
3. Low points on the cold side.
4. Wet ESFR next to a freezer relying on heating. When the heating fails, the pipe freezes.
5. Combustible-core panels ignored.
6. Faulty detection signal on a pre-action system. In a double-interlock system, no detection means no water.
7. Ammonia and fire scenarios not linked.

Design checklist

Frequently Asked Questions

Which sprinkler system is used in a freezer store?

Usually dry pipe or double-interlock pre-action. Double interlock is common in freezers because it stops the pipework filling and freezing after mechanical damage.

Can ESFR be used in a freezer?

ESFR heads are generally listed for wet systems only. Freezers use specially approved storage sprinklers suitable for dry or pre-action systems, or solutions combined with in-rack protection.

How are ice plugs prevented?

Dry the system air or use nitrogen, keep low points and drains on the warm side, arrange the freezer entry for inspection and drain the pipe completely after every test.

Why does the design area grow for dry systems?

Water reaches the heads later and the fire grows in the meantime. NFPA 13 increases the dry system design area by 30%, and EN 12845 also enlarges the area of operation for dry installations.

SprinkCalc — Fire Sprinkler Design Across Three Standards

SprinkCalc covers hazard classification, design density and area, K-factor selection, water demand and hydraulic calculations for NFPA 13, FM Global and BS EN 12845 in a single iOS app, and exports a professional PDF report.

Download SprinkCalc on the App Store