Dry Chemical System
A fixed dry chemical system floods a protected space with powder from a bank of pressurised cylinders through fixed piping and nozzles, giving the same chemical chain-breaking action as a portable extinguisher but sized to knock down a fire across a galley range, paint locker or helideck refuelling point in one release.
What to check on a Dry Chemical System.
4 models from Wilhelmsen Ships Service in Dry Chemical System. Below: the full model list.
What a fixed dry chemical system is for
Portable extinguishers cover a fire a crew member can reach and fight directly; a fixed dry chemical system is built for spaces where a fire can spread faster than a hand extinguisher can control it, or where crew access is limited during a fire, such as a galley deep-fat range hood and duct, a paint locker, or a helicopter deck fuelling point. Rather than relying on someone carrying an extinguisher to the seat of the fire, the system discharges powder automatically or by remote pull station through fixed piping and nozzles aimed directly at the hazard.
Main components
Powder storage cylinders
One or more pressure vessels hold the dry chemical charge, usually a sodium or potassium bicarbonate based powder chosen for the fire class expected in that space, kept dry and free-flowing by a moisture-tight fill and periodic condition checks.
Expellant gas cylinder
A separate cylinder of nitrogen or CO2 provides the propelling gas, either stored ready-connected or released by a pilot cylinder that then pressurises the main powder cylinders, depending on system design.
Read the full guide
Fixed piping and discharge nozzles
Sized and positioned during design to deliver a calculated powder density across the protected area or directly onto specific equipment, such as a fryer or duct opening, within seconds of activation.
Detection and release station
Heat or flame detectors trigger automatic release in unmanned or high-risk spaces; a manual pull station, always provided as a backup, lets crew release the system from outside the protected space.
Selection and sizing
The system is engineered to the specific hazard, not sold as a fixed capacity unit:
- Protected area or volume, and whether the hazard is a local point source such as a fryer versus a whole enclosure such as a paint locker.
- Powder type matched to the expected fire class, since bicarbonate powders suited to class B fires differ from the ammonium phosphate powders used for combined class A/B/C risk.
- Discharge time and powder quantity calculated to achieve extinguishing concentration before the fire can regrow, typically within ten to thirty seconds.
- Detection method appropriate to the space, balancing fast response against false discharge risk from normal galley heat.
Regulations and class
SOLAS Chapter II-2 requires fixed fire-extinguishing arrangements for galley ranges with deep-fat cooking equipment and for certain other specific hazards, and sets performance criteria the system's design must meet rather than mandating one brand or layout. Class societies require the system design to be approved against a recognised standard before installation, and periodic servicing, weighing of powder cylinders, and pressure testing of expellant gas cylinders at intervals set by the equipment standard, commonly aligned with the vessel's fire equipment survey cycle.
Typical faults
| Fault | Consequence |
|---|---|
| Caked or moisture-contaminated powder | Reduced or blocked discharge through the nozzles when the system is activated |
| Expellant cylinder pressure below charge weight | Powder is not propelled through the piping with enough force to reach the nozzles |
| Corroded or misaligned discharge nozzles | Powder pattern misses the actual hazard, such as the fryer surface or duct opening |
| Detector fouled by cooking grease | Automatic release fails to trigger, or triggers falsely from normal heat, eroding crew trust in the system |
| Manual pull station cable seized or disconnected | Backup release does not work when crew activate it during an actual fire |
What to look for in a supplier
- Approval to service the specific system brand and design, since powder chemistry and cylinder hardware are not interchangeable between manufacturers.
- Documented weighing and condition checks of powder cylinders at every service, not just a visual inspection.
- Ability to pressure test and, where due, hydrostatically retest the expellant gas cylinders on the same visit.
- Familiarity with galley hood and duct nozzle layouts specifically, since misaimed nozzles are a common installation-era defect that only shows up at commissioning test.
Ask for the actual discharge test result, not just a service sticker, whenever the system is due; a system that passes a static weight and pressure check can still fail to reach the fryer surface if a nozzle was reaimed or blocked during galley cleaning.
Models in this type.
The best-documented model of each manufacturer first, then the next — 4 of 4 models in Dry Chemical System. Every row links to full specifications, documents and service notes.
Manufacturers.
All 6 manufacturers with models of Dry Chemical System. Names with a manufacturer page open it; the others open a search across the full library.
All manufacturersAlso in Fixed Fire Suppression.
The other equipment types in this category.
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Three things people ask first.
Is Dry Chemical System data free?
Yes. Every model page, every guide and every datasheet for this type is readable without an account. An account adds saved searches and requests, nothing is taken away.
My model is missing — what now?
Send us the nameplate. We identify it by hand, add it to the library, and if you need a part or a service, the request is already on our desk.
Can you source a Dry Chemical System part?
Yes. Tell us the manufacturer, the model and what you need — a person reads every request and replies by e-mail.