Extinguishing agent stock and reserve: what to include in your design
Agent mass calculations determine how much is needed for suppression. Restoring protection after discharge needs a separate solution. We explain stock versus reserve and what to check in the specification.
How stock differs from reserve
Gaseous extinguishing agent is consumed on discharge. Modules must then be replaced with prepared units or sent for servicing and refilling. Restoration is therefore planned during design.
Stock
Prepared replacement modules for discharged units
Storage → installation → restorationReserve
Additional vessels connected to the system
Connection → switching → readinessThese terms are not interchangeable in an estimate: they involve different connections, configurations and staff procedures.
What to check under Kazakhstan standards
In SN RK 2.02-02-2023 (PDF), stock for multiple modular systems is addressed in Clause 9.1.18: it must suffice to restore the system discharged in any protected room. Clauses 9.1.19–9.1.20 provide for stock in similar modules ready for installation.
Reserve vessel connections and actuation are described separately in Clauses 9.1.28–9.1.30. The reserve is connected to the system; remote or automatic actuation follows discharge or failure to discharge the main quantity.
How to compare quotations
Compare quotations with the same scope of work and equipment. A low total price may cover only the primary equipment set.
| Item | What to clarify |
|---|---|
| Primary modules | Type, quantity, capacity and agent charge of each module |
| Stock | Compatibility, readiness for replacement and storage location |
| Reserve | Connection layout, fittings, actuators and controls |
| Maintenance | Replacement, transport, inspection and refilling procedure |
| Documents | Product passports, conformity documents and as-built documentation |
Agree the restoration time with your service provider in advance. It depends on site access, the availability of prepared modules and the required checks, rather than refilling time alone.
When several rooms are protected
The same agent mass does not make modules interchangeable. Installations may differ in agent type, cylinder capacity, pressure, valve assemblies and actuation method.
Make a table of rooms and module types, then check whether the selected spares can restore each installation. One nominally largest cylinder may not be enough for different equipment types.
When choosing an agent, consider future servicing as well. Read more in the article “Which fire suppression agent should you choose?”.
What to agree before purchase
- Primary agent quantity and the configuration of each installation
- Separate items for spares and a connected reserve, where specified
- Compatibility of spare modules with the installed equipment
- Storage location and conditions specified in the operating documentation
- People responsible for replacement, inspection and restoring protection
After an agent discharge, replacing modules is only part of the work. The procedure is covered in the article on ventilating the room and returning the site to service.