Cleanroom Fumigation and Decontamination Quantity Calculator (Room Volume, Agent Dose, Exposure Time)
Agent quantities for each room, the aeration time and the checklist before re-entry.
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Fumigation quantities and re-entry
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Results are estimates from the formulas shown, not a professional design or certification. Have a qualified engineer verify anything safety-critical (structures, electrical installations, gas or pressure systems).
About the Cleanroom Fumigation and Decontamination Quantity Calculator (Room Volume, Agent Dose, Exposure Time)
Works out the quantities for decontaminating cleanrooms by fumigation. List the rooms with their sizes (and any equipment volume to leave out) and choose the agent: vaporised hydrogen peroxide (at a target concentration or your cycle's injection per cubic metre), formaldehyde from paraformaldehyde or from formalin (the traditional method), or chlorine dioxide gas. The calculator gives each room's volume and quantity, the neutraliser or potassium permanganate your SOP uses, the concentration in ppm, an aeration time to the re-entry limit for well-mixed air, and a safety checklist for before and after the exposure.
The doses come from the CDC and NIH's Biosafety in Microbiological and Biomedical Laboratories (BMBL), Appendix B, and the re-entry limits from OSHA or your own site. It is an estimate for the facility's QA from published methods, not a professional design: your validated cycle sets the amounts and times, and a qualified person checks anything safety-critical before re-entry. The report follows the method you choose; your QA approves the result.
Without a pass the free preview runs the whole calculation and shows the verdict, every check, the limits that apply, the method and the full safety checklist; the quantities, the aeration estimate and the PDF, Word and Excel files and the printout unlock with an Ultimate pass.
How to use it
- List the rooms one a line: room; length; width; height; equipment volume to leave out (optional), in metres or feet; or room; volume.
- Choose the agent. For hydrogen peroxide vapour enter the target concentration (BMBL: 0.5 to under 10 mg/L, about 2.4) or your cycle’s injection per m³, and the solution’s strength and density.
- For formaldehyde keep BMBL’s standard of 0.3 g/ft³ (10.59 g/m³) or your cycle’s figure, the paraformaldehyde’s assay or the formalin’s content, your SOP’s neutraliser or permanganate ratio and the room’s relative humidity.
- Enter the exposure time of your validated cycle, the air changes an hour during aeration and the aeration you plan.
- Choose OSHA’s re-entry limit or enter your site’s, and add the detector reading before re-entry.
- Print the checklist for the cycle record, or save the plan as a PDF, a Word file or an Excel workbook, with an Ultimate pass.
Examples
Filling room 6 × 4 × 3 m with 2 m³ of equipment · 2.4 mg/L · 35 % solution at 1.13 g/mL · 60 minutes · 10 air changes an hour for aeration
70 m³: 168 g of hydrogen peroxide, 480 g (about 425 mL) of 35 % solution to reach the target once; 1,725 ppm; about 0.75 h of aeration to OSHA’s 1 ppm in well-mixed air.
A suite of 20 × 15 × 10 ft (3,000 ft³) · paraformaldehyde of 95 % assay · 70 % relative humidity
900 g of formaldehyde at 0.3 g/ft³, about 947 g of paraformaldehyde; about 8,600 ppm; humidity within BMBL’s 60 to 85 %.
Common uses
- Working out the paraformaldehyde, formalin or hydrogen peroxide for each room of a planned shutdown fumigation.
- Checking a formaldehyde cycle against BMBL’s standard concentration, humidity range and explosive limit.
- Estimating the aeration time before re-entry and printing the safety checklist for the cycle record.
- Converting a target concentration to ppm to compare with the re-entry limit.
The published doses
From BMBL, Appendix B (decontamination and disinfection), on space decontamination:
- Formaldehyde: the standard concentration for space decontamination is 0.3 g/ft³ (about 8,000 ppm) with a relative humidity of 60 to 85 %. Increasing the amount is not advised, as the lower explosive limit of formaldehyde gas is 7 % (70,000 ppm). Formaldehyde is a known human carcinogen: use the product per its label, prepare a fumigation management and safety plan in advance, and leave the work to highly experienced people.
- Hydrogen peroxide vapour: an effective sporicide at 0.5 to under 10 mg/L; about 2.4 mg/L with a contact time of at least one hour is optimal; for glove boxes, walk-in incubators and small rooms; it breaks down to water and oxygen.
- Chlorine dioxide gas: about 10 mg/L at the site with one to two hours of contact; generated on demand and usually diluted to 10 to 30 mg/L; broken down by light, with high humidity optimal.
EU GMP Annex 1, 4.36: where fumigation or vapour disinfection of cleanrooms is used, the effectiveness of the agent and its dispersion system is understood and shown by validation.
Re-entry limits and the aeration estimate
- OSHA 29 CFR 1910.1048: formaldehyde 0.75 ppm as an 8-hour time-weighted average, 2 ppm as a 15-minute short-term limit, action level 0.5 ppm.
- OSHA Table Z-1: hydrogen peroxide 1 ppm and chlorine dioxide 0.1 ppm (8-hour TWAs), ppm by volume at 25 °C and 760 torr.
- Other countries set their own limits: enter your site's.
The aeration estimate is the dilution of perfectly mixed air: t = ln(starting ppm ÷ re-entry ppm) ÷ air changes an hour. Real rooms give off agent from surfaces and absorbent materials, formaldehyde especially, so aeration often takes longer: a calibrated detector's reading decides re-entry.
Sources
- CDC and NIH: Biosafety in Microbiological and Biomedical Laboratories: Appendix B, decontamination and disinfection of laboratory surfaces and items
- OSHA 29 CFR 1910.1048: formaldehyde
- OSHA 29 CFR 1910.1000, Table Z-1: limits for air contaminants
- EU GMP, EudraLex Volume 4: Annex 1, 4.36
Limitations
- An estimate from published doses, not a cycle or a professional design: your generator’s validated cycle sets the amounts and times, and a qualified person checks every safety-critical step.
- Vapour generators inject more than the quantity that reaches the target once, because the vapour breaks down and condenses; use your cycle’s injection per m³ for the amount actually used.
- The planner sets no permanganate or neutraliser ratio and no formaldehyde exposure time: enter your SOP’s.
- The aeration estimate assumes well-mixed air with nothing given off from surfaces; the detector reading decides re-entry.
- Up to 40 rooms at a time.
- The report follows the method you choose; your QA approves the result.
- Runs in any current browser on a phone, tablet or computer: the report is worked out as you type, and the PDF, Word and Excel writers load only when you save a file.
Privacy
On this device: nothing is sent
Your rooms and figures stay in this browser and are never sent anywhere. The PDF, Word and Excel files are made on your device.
Frequently asked questions
What do I get without a pass?
Without a pass, Cleanroom Fumigation and Decontamination Quantity Calculator (Room Volume, Agent Dose, Exposure Time) shows the method, the limits that apply and the verdict for your input; computed figures stay hidden until the pass. Until you unlock it, the result can’t be downloaded or printed. An Ultimate pass, a one-time payment unless you choose automatic renewal, unlocks the full result. The pricing page lists the passes and their prices.
What does the Ultimate pass add here?
This tool in full, and every other Pro, Premium and Ultimate tool, for 7 days, 30 days or a year (a pass bought with PayPal leaves out email-address extractors). The pass is a one-time payment unless you choose automatic renewal.
How much paraformaldehyde do I need to fumigate a room?
BMBL gives a standard formaldehyde concentration of 0.3 g per cubic foot (10.59 g/m³) for space decontamination, at 60 to 85 % relative humidity. A 3,000 ft³ suite takes 900 g of formaldehyde: divide by the paraformaldehyde’s assay (95 % gives about 947 g). BMBL advises against using more.
How much hydrogen peroxide does a VHP cycle use?
Reaching about 2.4 mg/L once takes 2.4 g of hydrogen peroxide per m³, or about 6.9 g of 35 % solution per m³; generators inject more over the cycle as the vapour breaks down and condenses. Enter your validated cycle’s injection per m³ for the amount actually used.
How long should a room be aerated before re-entry?
Until a calibrated detector reads at or below the re-entry limit (OSHA: 0.75 ppm for formaldehyde, 1 ppm for hydrogen peroxide, 0.1 ppm for chlorine dioxide, or your site’s limit). The calculator estimates the time for well-mixed air, ln(starting ppm ÷ limit) ÷ air changes an hour, as a planning figure.
Why does the relative humidity matter for formaldehyde?
BMBL gives a relative humidity of 60 to 85 % for formaldehyde space decontamination. The calculator fails a reading outside that range so the room is conditioned before the agent is released.
Is this a validated fumigation cycle?
No. It works out quantities and times from published doses and your own figures, as an estimate for your QA. Annex 1, 4.36, asks for the effectiveness of the agent and its dispersion system to be understood and shown by validation at your site.