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Ammonia
Ammonia (CAS 7664-41-7) — Industrial chemical and refrigerant. What OSHA's HazCom rules ask of it on a job site, and where its Safety Data Sheet comes from: your supplier.
Verified vs OSHA sources · October 5, 2026
CAS Registry Number CAS 7664-41-7 · also known as Anhydrous ammonia, NH3
Overview
Industrial chemical and refrigerant
Ammonia on the job site
Ammonia reaches job sites as the R-717 refrigerant in industrial refrigeration and as the active ingredient in some strong cleaners. As a gas it is corrosive and a severe respiratory and eye hazard, but it has one thing going for it: its sharp smell is detectable well below the 50 ppm PEL, so it warns you. The danger is a large leak in a mechanical or machine room, where concentrations climb fast to eye-damaging and immediately-dangerous levels.
The rule is not to enter a space with a strong ammonia leak to “find it” without proper respiratory protection (SCBA) and training — that's how responders get hurt. For cleaners, never mix an ammonia product with bleach: the reaction releases toxic chloramine gas. Ventilation, eye protection, and gloves cover routine cleaning use.
Key takeaways
- Ammonia's sharp smell warns below the 50 ppm PEL — but a machine-room leak can reach eye-damaging levels quickly.
- Don't enter a strong-leak space to investigate without SCBA and training.
- Never mix ammonia cleaners with bleach — it makes toxic chloramine gas.
Field guidance for planning and training — not a substitute for the manufacturer Safety Data Sheet, which gives the exposure limits, PPE, and handling for your specific product.
OSHA Exposure Limits
OSHA permissible exposure limit (PEL) and secondary limit for Ammonia on a US construction site. Where a substance-specific 1926 standard applies, its codified limit is shown; otherwise the figure comes from Table 1 to 29 CFR 1926.55, the construction air-contaminants table. Where 1926.55 does not list the substance, OSHA sets no construction limit for it; Section 8 of the Safety Data Sheet lists the limits other bodies recommend and the supplier's controls.
| Limit | Value | Basis / citation |
|---|---|---|
| OSHA PEL (8-hr TWA) | 50 ppm | 29 CFR 1910.1000 Table Z-1 |
| Action level | See SDS / standard | Not all substances define an action level |
| Averaging period | 8-hour TWA | Compare with ACGIH TLV / NIOSH REL — often more protective than the OSHA PEL |
This is the general-industry figure. Construction air contaminants are listed separately in Table 1 to 29 CFR 1926.55, and on 33 substances the two differ — sometimes by a wide margin. Where they differ, the construction value governs work on a jobsite.
Many OSHA PELs date to 1971 and may be less protective than current ACGIH/NIOSH values; always check Section 8 of the manufacturer SDS for the limits it lists, which can be lower than the PEL, and for its control guidance. Not legal advice.
GHS Classification
Physical Properties
Where Ammonia shows up on the job
Trades that commonly handle Ammonia, each with an OSHA HazCom guide built for the chemicals and tasks on that kind of site:
OSHA & HazCom Compliance Requirements
For construction work, Hazard Communication is governed by 29 CFR 1926.59 (adopts 29 CFR 1910.1200). Employers who use Ammonia must:
- •Maintain an accessible SDS for Ammonia (readily accessible during each work shift, 29 CFR 1910.1200(g)(8))
- •Label all containers with GHS-compliant labels (29 CFR 1910.1200(f)(1) shipped / 29 CFR 1910.1200(f)(6) workplace)
- •Include it in the workplace chemical inventory
- •Train employees on hazards before initial assignment
- •Retain employee exposure and medical records per 29 CFR 1910.1020 — 30-year retention applies to exposure/medical records, not to SDSs generically
HazCom (1910.1200 / construction 1926.59) covers labels, SDSs, and training only — it does not impose chemical storage segregation. Flammable & combustible liquid storage for construction is 29 CFR 1926.152; segregation of incompatibles is planned from SDS Sections 7 and 10. Not legal advice; state-plan states may have stricter rules.
Handling & Secondary-Container Labeling
When you transfer Ammonia into a workplace (secondary) container, OSHA gives two compliant options under 29 CFR 1910.1200(f)(6):
- •(f)(6)(i): full GHS label elements (as on the shipped container)
- •(f)(6)(ii): product identifier + words/pictures/symbols (or combination) that provide AT LEAST general information on the hazards and, with the other information immediately available under the HazCom program, the specific hazards
There is no volume/size cutoff for secondary containers — the ≤100 ml / ≤3 ml accommodations (29 CFR 1910.1200(f)(12) (added by the HCS 2024 final rule)) apply only to the manufacturer's shipped container. A portable container filled for the immediate use of the worker who fills it needs no label (29 CFR 1910.1200(f)(8)).
GHS Hazard Classification under OSHA HCS
OSHA's Hazard Communication Standard adopts the GHS (primarily GHS Revision 7 (HCS 2024)). It requires 8 hazard pictograms (Appendix C, Figure C.1). The Environment pictogram (GHS09) is not required by OSHA — Not in App C; outside OSHA jurisdiction; voluntary.
The 8 OSHA-required pictograms:
For flammable liquids, OSHA classifies by flash point and boiling point (App B.6.1 / 1910.106(a)):
- •Category 1: FP < 73.4°F AND BP <= 95°F
- •Category 2: FP < 73.4°F AND BP > 95°F
- •Category 3: FP >= 73.4°F AND <= 140°F
- •Category 4: FP > 140°F AND <= 199.4°F
The specific GHS classification of Ammonia comes from its Safety Data Sheet (Section 2). Use the live classification panel above and the manufacturer SDS to confirm pictograms and categories.
HCS 2024 Update Deadlines
Under the Hazard Communication Standard 2024 update (aligned primarily GHS Revision 7):
- •May 19, 2026 — manufacturers, importers, and distributors update substance labels & SDSs (1910.1200(j)(2)(i))
- •November 20, 2026 — employers update workplace labeling, the written program & training (1910.1200(j)(2)(ii))
During the interim, parts may comply with the 2012 HCS, the 2024 HCS, or both.
Quick Actions
Put Ammonia on your written inventory, print the workplace label your containers need, and keep your supplier’s sheet reachable on the jobsite.
The safety data sheet for your product comes from the supplier who sold it to you — no public registry can provide it. For the underlying chemistry, the public record is on PubChem.
Where this fits in your HazCom program
- SDS management — collecting the sheet, keeping it current, and making it readable during each work shift.
- GHS labels & workplace labeling — what has to appear on the shipped container, and what a secondary container needs instead.
Free Compliance Tools for Ammonia
Also on a hvac/r job
Frequently Asked Questions
What is Ammonia (CAS 7664-41-7)?
Industrial chemical and refrigerant
What are the OSHA HazCom requirements for Ammonia on a construction site?
For construction work, Hazard Communication is governed by 29 CFR 1926.59 (adopts 29 CFR 1910.1200). Where a product you use containing Ammonia is a hazardous chemical under the standard (its supplier's label and SDS say so), you must keep its Safety Data Sheet accessible, keep the supplier's label on shipped containers and label workplace containers under (f)(6), list it in the written program's chemical inventory, and train workers on its hazards at initial assignment. Exemptions apply, such as a consumer product used the way a consumer would use it (1910.1200(b)(6)(ix)).
What is the OSHA permissible exposure limit (PEL) for Ammonia?
OSHA's permissible exposure limit for Ammonia is 50 ppm (8-hour TWA), per 29 CFR 1910.1000 Table Z-1. That figure is the GENERAL-INDUSTRY limit; construction air contaminants are listed separately at 29 CFR 1926.55 Table 1, and where the two differ the construction value governs work on a jobsite. Where the ACGIH TLV or NIOSH REL is more protective, follow the lower value, and confirm the limit for your specific task against Section 8 of the manufacturer Safety Data Sheet.
When does the updated HCS 2024 labeling apply to Ammonia?
Under the Hazard Communication Standard 2024 update (aligned primarily GHS Revision 7), manufacturers, importers and distributors must comply by May 19, 2026 when Ammonia is sold as a substance, and by November 19, 2027 for mixtures that contain it. Employers must, as necessary, update alternative workplace labels, the written program and training for newly identified hazards by November 20, 2026 for substances and May 19, 2028 for mixtures (29 CFR 1910.1200(j)). During the interim, parties may comply with the 2012 HCS, the 2024 HCS, or both.
How do I label a secondary (workplace) container of Ammonia?
Under 29 CFR 1910.1200(f)(6) you have two options: (i) the label elements of (f)(1)(i) through (v): product identifier, signal word, hazard statements, pictograms and precautionary statements, with no supplier name or address needed, or (ii) the product identifier plus words, pictures, symbols, or a combination that provide at least general hazard information and that, with the other information immediately available to workers under the HazCom program, give the specific hazards. There is no volume/size cutoff for secondary containers. A portable container filled from a labeled container, kept under the control of the worker who fills it and used only by that worker within the same shift, does not require a label (29 CFR 1910.1200(f)(8)).
How long must SDS and exposure records for Ammonia be kept?
Under 29 CFR 1910.1020, 30-year retention applies to employee exposure and medical records (medical records: duration of employment plus 30 years) — not to SDSs generically. Where an SDS is not retained, a record of the chemical's identity, where it was used, and when must be kept for at least 30 years.
Where can I find the SDS for Ammonia?
Under 29 CFR 1910.1200(g)(6) and (g)(7), the manufacturer, importer or distributor that sold you Ammonia must send its Safety Data Sheet with the first shipment, and again with the first shipment after the sheet is updated. HazComFast keeps the sheets you collect in one inventory per jobsite, searchable by product, manufacturer or CAS number, and your jobsite's SDS load onto the phone on their own.
Sources & Primary References
Regulatory data on this page is sourced from HazComFast's verified regulatory module (29 CFR 1926.59 / 1910.1200 and substance-specific 1926 standards), last verified October 5, 2026 against eCFR, OSHA.gov, and the Federal Register. Physical-property data comes from PubChem. Confirm it against the manufacturer Safety Data Sheet. This page is informational and is not legal advice.
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