Dry Sprinkler Head

The total tube length = construction depth (thickness of insulated panel, slab, or void) + deflector standoff below the finished cold-side ceiling surface. NFPA 13 requires the deflector to be positioned 75–150 mm below the ceiling surface (or below obstructions) in the cold zone to allow the spray pattern to fully develop.

For example: a 200 mm thick insulated cold-store ceiling panel with a 100 mm deflector standoff below the cold face requires a total tube length of 300 mm. Add any escutcheon recess depth at the warm-side end to get the final order length. If in doubt, round up to the next 50 mm increment — tube length does not affect hydraulic performance.

No. Dry sprinkler heads in the CA-FIRE T-ZSTGX and T-ZSTGDY range are designed exclusively for pendent (downward) installation. The internal valve mechanism relies on gravity and water pressure acting downward — inverting the head to an upright position would prevent the valve from seating correctly and could allow water to enter the tube in a non-activation state.

For spaces requiring upright installation in a cold zone (such as sub-floor sprinkler protection beneath a raised access floor), a dedicated dry-pipe or pre-action system covering that zone is the appropriate solution, rather than an individual dry sprinkler head.

A dry-pipe system replaces the entire pipe network with pressurised air or nitrogen. When any sprinkler activates, the air pressure drops, a dry-pipe valve trips, and water fills the entire network before flowing from the activated head. This involves significant equipment (dry-pipe valve, air compressor, accelerator, low-point drains) and the water delivery delay can be 30–60 seconds or more, depending on pipe volume.

A dry sprinkler head is a single component. Only the individual head's extension tube contains air — the branch pipe and all main pipes remain wet and pressurised. When the head activates, water only has to travel down the tube of that one head (typically 80–1500 mm), so water delivery time is essentially the same as a standard wet-pipe head — far faster than a full dry-pipe system.

Dry heads are the preferred solution when the cold zone is small (a single room, a loading dock, or a canopy) within an otherwise wet-pipe protected building. Full dry-pipe systems are appropriate when the entire facility is sub-zero or when the code requires a complete dry-pipe system for the occupancy type.

No — dry sprinkler heads must not be cut, extended, or modified on site. The tube length is factory-set and the internal valve and sealing components are assembled and tested at that specific length. Modifying the tube length in the field would void the product certification and invalidate the CCCF type approval.

If the required length changes between order and installation (due to revised construction details, for example), contact CA-FIRE to confirm whether a replacement at the correct length can be supplied before proceeding with installation.

For most cold-store and freezer applications, the 5mm standard response glass bulb (RTI 50–80) is the standard and more common specification. The 3mm quick response bulb (RTI ≤50) is available in the K5.6 and K8.0 T-ZSTGX series for applications where NFPA 13 or the design authority requires quick response — for example, in residential cold zones or where the occupancy hazard classification mandates QR heads.

For the K25.2 (K=363) series and the ESFR dry-type (DT) models, a fusible alloy link is used rather than a glass bulb. The fusible alloy provides reliable activation across the wide temperature range seen in heavy industrial cold stores, and its RTI characteristics (80–360) are appropriate for the large-K, high-flow-rate applications these heads serve.