A portable fire extinguisher is certified for specified fire classes and contains a particular extinguishing agent. This explanatory cutaway shows one generic stored-pressure dry-chemical arrangement; it is not a universal extinguisher design or an operating recommendation.
Fire Extinguisher Interactive Calculator
Enter charge mass and discharge duration from a specific certified product label, plus a separate released fraction to compare released and remaining mass. Pressure is not used to predict flow.
Equation Used
- Charge mass and duration are copied from the same certified extinguisher documentation.
- Released fraction is an independent user input for comparing released and remaining mass.
- No pressure, pressure decay, agent rheology, valve/nozzle, usable residue or fire-suppression model.
- No extinguisher selection, inspection pass/fail or firefighting decision is made.
Actual discharge varies by certified extinguisher, agent, valve/nozzle and condition. Use the product label and manufacturer instructions.
Generic stored-pressure arrangement
In the illustrated arrangement, agent occupies the lower cylinder and a pressurized gas space occupies the top. Operating the certified valve opens a path from the siphon tube to the hose and nozzle. The pressure and agent behavior during discharge depend on the specific product and are not simulated here.
The moving particles and fill level explain the route and show the separately entered released fraction. They do not show real pressure decay, powder flow, nozzle range or extinguishing performance.
Read the certified label first
USFA explains that extinguisher agents and classes differ and recommends listed equipment. OSHA requires workplace selection and distribution based on anticipated fire classes and hazard, plus inspection, maintenance and training where extinguishers are provided for employee use.
Enter only the charge mass and duration stated for one specific certified product. The calculator can convert units and divide those two entered values; it cannot select equipment or decide whether anyone should fight a fire.
Entered-value calculations
Arithmetic average mass rate is m/t using entered label charge m and duration t. Released and remaining masses are mf and m(1−f), where f is separately entered. Pounds are converted from kilograms using 1 lb=0.45359237 kg.
Pressure alone cannot determine discharge rate. A physical prediction would also require the specific agent, cylinder, valve, nozzle and manufacturer discharge curve.
Example without a flow prediction
If one product label states 5 kg charge and 20 s duration, simple division gives 0.25 kg/s average. Entering 50% released divides the charge into 2.5 kg released and 2.5 kg remaining for illustration. It does not say the real extinguisher reaches that fraction halfway through discharge.
Safety boundary
This page does not replace the extinguisher label, listing, manufacturer instructions, fire department guidance, workplace emergency plan or required training. It does not calculate pressure, range, discharge trajectory, fire rating, agent compatibility or suppression performance.
OSHA places responsibility for selection, distribution, inspection, maintenance, testing and employee education/training on the employer where portable extinguishers are provided. USFA advises considering whether the fire is small and contained, whether people have been alerted and emergency services called, whether the user is trained and physically able, and whether smoke conditions are safe.
Questions
Can gauge pressure alone predict discharge?
No. Discharge also depends on the agent, cylinder, valve, nozzle and product-specific behavior.
Does the animation tell me which extinguisher to use?
No. Use the certified class/rating label and applicable fire-safety guidance.
Is average mass rate an actual flow curve?
No. It is only charge divided by entered label duration.
Official guidance
Component reference: Amerex Portable & Wheeled Parts Book, 27277 Rev C, page 3, shows the lever, valve, spring, downtube, cylinder and hose of portable dry-chemical extinguishers. The animation is a generic explanation, not a dimensional service drawing.
OSHA 29 CFR 1910.157, Portable Fire Extinguishers: selection/distribution, maintenance, inspection, testing and training requirements.
U.S. Fire Administration, Choosing and Using Fire Extinguishers: extinguisher classes, listed equipment and conditions to consider before use.
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