AquaMist ULF AM11
Tyco (Johnson Controls) AquaMist ULF AM11 — Ultra Low Flow (Low-pressure) closed (automatic) nozzle for Class A fire suppression in engineered water mist systems.
Inspector Detail
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Common issues
- Nozzle orifice or upstream strainer blockage from pipe scale or debris, reducing discharge performance
- Thermal (glass bulb) release element painted over or contaminated, delaying or preventing activation
- Incorrect temperature-rated bulb fitted after a nozzle replacement
- Corrosion or pitting of stainless steel/brass nozzle bodies in an aggressive engine room atmosphere
- Missing or damaged protective dust cap allowing pre-activation blockage of the orifice
- Zone/section valve failing to open fully on test, reducing pressure delivered at the nozzle
Inspection checklist
- Visual check of every nozzle for missing/painted bulb, dust cap in place, and no physical damage
- Verify nozzle orientation and spacing have not been altered by adjacent pipework or equipment changes
- Check pipework and strainers for internal corrosion or scale during periodic flushing
- Functional test of the pump unit and zone/section valves to design pressure per the approved test procedure
- Verify pressure gauge readings at test points fall within the design range for this nozzle type
- Check nozzle count and layout against the approved fire control drawing for the protected space
- Confirm automatic and manual release, plus alarm functions, operate correctly
- Inspect the pump skid, accumulator and associated piping for leaks
Service intervals
| Visual inspection of all nozzles (bulb, cap, orientation) | every 12 months |
| Pressure/flow functional test of pump unit and zone valves | every 12 months, per the approved maintenance schedule |
| Strainer cleaning/inspection | every 12 months or per maker instructions |
| Full system discharge test (representative section) | per class/flag requirement, commonly at 5-year survey intervals |
Typical wear limits
| Nozzle/system operating pressure | designed for 7-12 bar (101.5-174.0 psi) at the nozzle per the maker's data - confirm the actual figure against the vessel-specific approved hydraulic calculation, not this range alone |
Ranges are typical for this design class. Always confirm against the manufacturer documentation for your serial number.
Critical spares
- Replacement nozzles of the correct type and thermal rating (closed automatic, ultra-low-flow)
- Spare glass bulb release elements of the matching temperature rating
- Nozzle dust caps
- Strainer elements
- Zone/section valve seals and actuator components
Safety
- System piping operates at 7-12 bar - isolate and depressurize before maintenance
- An incorrect bulb temperature rating can cause nuisance activation or fail to activate in a real fire
- Nozzles are tested devices - fitting a non-approved substitute invalidates the Class A fire test basis for the protected space
- Residual pressure/water hammer risk when reopening an isolated section
Class survey
Water mist (Hi-Fog type) systems are Continuous Survey Machinery items on classed vessels; surveyors typically review maintenance records for periodic pump/valve function tests and nozzle visual condition, and check that any replacement nozzles carry the same type approval as the original installation.
Components & Design
Component data being added…
Technical Data
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Common failures & inspection points
Visual inspection of all nozzles to confirm no obstructions, corrosion deposits, or mineral buildup affecting spray pattern; check for physical damage to diffusers
Monthly verification that water pressure complies with pump specification and operational characteristic curve; confirm pump operates without abnormal noise or leakage; monthly pump testing
Hydraulic testing of all pipework at 1.5 times normal working pressure for minimum 2 hours during commissioning; ongoing monitoring of water supply filtration systems to prevent nozzle clogging
Inspection of valves, control stations, detection devices, batteries, and alarms for functionality; verification of check valve operation and sectional control valve response; testing every 6 months with monitoring service
Verification of current Certificate of Compliance from installation contractor; confirmation that Design, Installation, Operation and Maintenance (DIOM) handbook is on-site; validation of FM/VdS/UL/IMO certification compliance for system configuration
Type-general inspection and maintenance points for this equipment category — not model-specific.
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