Respirator selection
Hydrogen chloride respirator selectionHCl
Steel pickling, chemical manufacturing, metal etching, oil-well acidizing, water treatment; anhydrous gas and aqueous (muriatic/hydrochloric acid).
These are federal OSHA limits. The PEL shown is the federal OSHA value. About two dozen states run their own OSHA-approved plans, and some — notably California (Cal/OSHA) — enforce lower or additional exposure limits. If you work under a state plan, check your state's PEL and enter it as a custom limit in the calculator.
Recommended cartridge: Acid Gas (AG) — White band
An APR fitted with the correct cartridge is only adequate up to its MUC (below) — the cartridge must be able to capture hydrogen chloride. IDLH 50 ppm caps use; above it supplied air/SCBA required. Add a P100 particulate prefilter if acid mist is present. Cartridge must be NIOSH-approved for HCl. Good warning properties (pungent odor). You must establish a change-out schedule; never rely on taste or smell. See the cartridge & filter guide.
The OSHA limit for hydrogen chloride is a ceiling value, not an 8-hour average. The MUC method below is defined for time-weighted limits, so apply professional judgment.
Calculator for Hydrogen chloride
Result
Enter a concentration and an exposure limit to see the
compliant respirators and their Maximum Use Concentration.
Hazard ratio = concentration ÷ OEL · Minimum APF must meet or exceed it · MUC = APF × OEL (capped at IDLH). Source: OSHA 29 CFR 1910.134(d)(3)(i)(A), Table 1 — Assigned Protection Factors. Last verified 2026-07-16.
Maximum use concentration for Hydrogen chloride by respirator
MUC = APF × the OSHA PEL (5 ppm), capped at the IDLH (50 ppm). Use this as a reference for the highest concentration each respirator class may be used at.
| Respirator | APF | MUC (ppm) |
|---|---|---|
| Air-Purifying Respirator · Quarter mask | 5 | 25 |
| Air-Purifying Respirator · Half mask | 10 | 50 |
| Supplied-Air Respirator (Airline) · Half mask · Demand | 10 | 50 |
| Self-Contained Breathing Apparatus · Half mask · Demand | 10 | 50 |
| Powered Air-Purifying Respirator · Helmet / hood | 25 | 50IDLH |
| Powered Air-Purifying Respirator · Loose-fitting facepiece | 25 | 50IDLH |
| Supplied-Air Respirator (Airline) · Helmet / hood · Continuous flow | 25 | 50IDLH |
| Supplied-Air Respirator (Airline) · Loose-fitting facepiece · Continuous flow | 25 | 50IDLH |
| Air-Purifying Respirator · Full facepiece | 50 | 50IDLH |
| Powered Air-Purifying Respirator · Half mask | 50 | 50IDLH |
| Supplied-Air Respirator (Airline) · Full facepiece · Demand | 50 | 50IDLH |
| Supplied-Air Respirator (Airline) · Half mask · Continuous flow | 50 | 50IDLH |
| Supplied-Air Respirator (Airline) · Half mask · Pressure-demand / positive-pressure | 50 | 50IDLH |
| Self-Contained Breathing Apparatus · Full facepiece · Demand | 50 | 50IDLH |
| Powered Air-Purifying Respirator · Full facepiece | 1,000 | 50IDLH |
| Supplied-Air Respirator (Airline) · Full facepiece · Continuous flow | 1,000 | 50IDLH |
| Supplied-Air Respirator (Airline) · Full facepiece · Pressure-demand / positive-pressure | 1,000 | 50IDLH |
| Self-Contained Breathing Apparatus · Full facepiece · Pressure-demand / positive-pressure | 10,000 | 50IDLH |
Notes
Both NIOSH REL and OSHA PEL are Ceiling 5 ppm (7 mg/m3), not to be exceeded at any time. IDLH 50 ppm on the current NPG card. IMPORTANT: NIOSH published a revised IDLH Value Profile in 2025 (DHHS/NIOSH Pub 2025-110) lowering the calculated IDLH to 45 ppm; NPG card not yet updated at check time — treat 45 ppm as the more current NIOSH figure. Conversion 1 ppm = 1.49 mg/m3; MW 36.5.
Sources
- https://www.cdc.gov/niosh/npg/npgd0332.html
- https://www.osha.gov/annotated-pels/table-z-1
- https://www.cdc.gov/niosh/docs/2025-110/pdfs/2025-110revised062025.pdf
Data confidence: high. Values are cited from OSHA and NIOSH but should be verified against the current source and a qualified professional before use. See how this works.