Ship Compressed Air System Capacity Tool

Service Air • Control Air • Compressor FAD • Receiver Storage • Peak Demand • Pressure Decay • N-1 • Recovery • Dryer Loss • Control Reserve

Ship Compressed Air System Capacity Tool

Size and stress-test the ship's low-pressure service and control-air plant. Simple mode checks normal compressor loading, a short-duration peak, receiver pressure drawdown and recovery. Advanced adds individual consumers, compressors, receivers, compressor response delay, N-1 operation, control-air reserve, downstream pressure loss, optional reduced starting-air backup and a time-domain pressure transient.

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Service/control air, not starting-air receiver sizing.Use the separate Starting Air Receiver & Compressor Tool for class/OEM engine-start reserve. This tool focuses on the lower-pressure utility and control-air plant.

CapacityFAD vs continuous demand

TransientPeak pressure drawdown

RecoveryReceiver refill time

Normal & Peak Air Demand

Continuous demandm³/h free air.

Additional peak demandm³/h free air above normal demand.

Peak durationseconds.

Available compressor FADm³/h free-air delivery.

Receiver Pressure Band

Active receiver volumem³ geometric volume.

Cut-out / starting pressurebar(g).

Compressor cut-in pressurebar(g).

Minimum acceptable receiver pressurebar(g).

Atmospheric reference pressurebar absolute.

Compressor response delayseconds before full available FAD is assumed during the peak.

Service-Air Pressure / Storage Basis

Cut-out / initial receiver pressurebar(g).

Compressor cut-in pressurebar(g).

Minimum acceptable receiver pressurebar(g).

Atmospheric reference pressurebar absolute.

Free-air reference temperature°C.

Receiver air temperature°C for ideal-gas storage correction.

Compressor full-output response delayseconds after transient begins.

Downstream dryer / line pressure lossbar at the critical-user peak condition.

Minimum critical-user pressurebar(g) after entered downstream loss.

Compressed-Air Consumer Register

Normal and peak figures are free-air equivalent demands. During the transient, each enabled consumer is assumed to start at its entered peak and return to normal after the entered peak duration.

Use	Service	Critical?	Normal FAD m³/h	Peak FAD m³/h	Peak duration sec

Service-Air Compressor Register

Capacity factor can represent ambient condition, fouling or a measured derate. FAD is free-air delivery. Nameplate motor power is used only for an installed specific-power indicator, not a compressor performance guarantee.

Use	Available?	Rated FAD m³/h	Capacity factor %	Motor kW	Control

Service-Air Receiver Register

Use	Available?	Volume m³	Usable volume %

Control-Air Reserve Branch

Control-air receiver volumem³.

Control receiver initial pressurebar(g).

Minimum control-air pressurebar(g).

Pressure dew-point target°C, user-entered operating target. ISO 8573-1 class selection remains application-specific.

Optional Reduced Starting-Air Backfeed

Some ships can supply lower-pressure working/control air from the starting-air system through reduction. This is a contingency input only. Starting-air receiver depletion and engine-start reserve are not modeled here.

Backfeed available?

Reduced backup FAD limitm³/h free-air equivalent.

Include in transient capacity?

Compressed-Air Plant Checks

Compressor FAD verifiedEntered capacities are maker data or measured free-air delivery at the relevant condition. Receiver volume / pressure band verifiedActive receiver volume, cut-in, cut-out and minimum pressure match the actual plant. Control air is dried and filteredAir-treatment arrangement and pressure dew point are suitable for automation equipment. Automatic drains / separators checkedCondensate accumulation is not reducing usable receiver volume or contaminating the network. Peak consumers confirmedSimultaneous deck tools, soot blowing, maintenance and other short-duration loads are represented. N-1 compressor availability checkedIsolation, electrical supply and standby sequencing support the entered contingency case. Pressure losses / dryer condition checkedFilter, dryer, valve and distribution losses are represented at the critical user. Starting-air reserve protectedAny reduced starting-air backfeed is managed without compromising approved engine-start reserve.

System boundary: this is a low-pressure service/control-air capacity and storage screen. It does not replace the ship's approved starting-air calculation, compressor performance curve, pressure-vessel certification, air-quality verification or piping pressure-drop analysis.

Engineering basis: marine working air commonly serves tools, cleaning and general services, while control/instrument air requires cleaner and drier air for valves and automation. Receiver storage can cover short peaks that exceed instantaneous compressor output. The transient model converts free-air deficit into receiver pressure change using an ideal-gas storage approximation. ISO 8573-1:2010 remains the published compressed-air purity-class standard while a revision project is under development.

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