Calibration Gases

NIST Traceable Calibration Gases & Custom Mixtures

Apollo Safety stocks a complete line of NIST traceable calibration gases and custom gas mixtures for calibrating portable and fixed gas detection instruments. Whether you need a single-gas cylinder for CO, H2S, O2 or methane (LEL), or a multi-component 4-gas calibration mixture, our calibration gas delivers accurate, OSHA- and ANSI-compliant results for industrial, commercial, and safety applications.

Calibration gas is the baseline that keeps your gas detector calibration trustworthy. Drifted sensors produce false readings — and a false zero or span can mean the difference between an alarm and a miss. That's why every cylinder we ship is NIST traceable, with a certificate of analysis, in aluminum or steel sizes from 17L to 650L.

Calibration Gases in Stock

• Ammonia (NH3) — 10, 25, 100, 200 ppm
• Carbon Monoxide (CO) — 25, 50, 100, 300, 500 ppm
• Chlorine (Cl2) — 2, 5, 10 ppm
• Hydrogen (H2) — 10% LEL, 50% LEL
• Hydrogen Sulfide (H2S) — multiple ppm concentrations
• Hydrogen Cyanide (HCN)
• Methane (CH4) — 5% LEL, 10% LEL, 50% LEL, 99.9% vol
• Nitrogen (N2) — 99.9% vol
• Sulfur Dioxide (SO2) — 5, 10 ppm
• Silane (SiH4) — 5, 10 ppm
• Hexane — 15% LEL

Many other concentrations, balance gases, and custom calibration mixtures are available — if you don't see it, ask.

How to Choose the Right Calibration Gas

Choosing correctly comes down to three decisions:

1. Match the gas and range to your sensor. Calibrate at the concentration you actually monitor — typically around 50% of the alarm setpoint. For LEL (combustible) sensors use a % LEL mixture (e.g., 50% LEL methane or propane); for toxic sensors use ppm.
2. Pick the balance gas. Nitrogen-balance gas is the standard for most monitors and isolated sensors; air-balance (20.9% O2) is used when calibrating an oxygen sensor or when the instrument is specified to calibrate in air.
3. Size the cylinder and regulator. A 58L aluminum cylinder suits most field calibration; high-volume or daily-use instruments use 116L or 650L. Pair it with the correct CGA regulator — we stock calibration gas regulators (CGA-590, CGA-600, CGA-C10) at 0.5–1.0 LPM.

Popular Multi-Gas Calibration Mixtures

Most 4-gas and multi-gas monitors (such as Ventis, MultiGauge, and RAE Series) calibrate with a blend. Our most requested combinations include:

• 25 ppm H2S + 100 ppm CO + 50% LEL CH4 + 18% O2
• 25 ppm H2S + 100 ppm CO + 25% LEL pentane + 18% O2
• 25 ppm H2S + 100 ppm CO + 50% LEL CH4 + 10 ppm SO2

Not on the list? We build custom calibration mixtures to your exact specification.

Calibration Gas for Confined Space, Wastewater & Industrial Use

From fixed point gas detectors to portable multi-gas units, calibration gas supports every industry that lives with hazardous atmospheres — confined space entry, wastewater treatment, oil & gas, manufacturing, HVAC, and battery rooms. Pair your gas with our 100% Compliance calibration and repair service, where calibrations are completed within 24 hours and repairs within 48.

Frequently Asked Questions

How often should I calibrate my gas detector?

Most standards and manufacturers recommend at least every 6 months, plus a daily bump test before field use. OSHA and ANSI treat calibration as part of routine gas detection maintenance.

What does "NIST traceable" mean?

It means the cylinder's concentration is measured and certified against a chain of reference standards traceable to the National Institute of Standards and Technology, so you can verify your instrument against a known, defensible value.

Nitrogen balance or air balance — which do I need?

Use nitrogen balance for most toxic and combustible calibrations. Use air balance (20.9% O2) when calibrating an oxygen sensor or when your monitor is specified to calibrate in air.

Can you make a custom mixture?

Yes. We formulate custom single- and multi-gas calibration mixtures to your specification, in the cylinder size you need.

How do I store and ship the cylinder?

Cylinders ship DOT-compliant and should be stored upright, secured, and away from heat. Most unopened calibration gas has a multi-year shelf life — confirm the date on the cylinder label.

Call toll-free 800-813-5408 to speak with one of our gas detection experts, or schedule your calibration today.

Prices are subject to change without notice due to ongoing tariff adjustments and market conditions. For the most accurate and up-to-date pricing, please contact us directly.