Selecting the correct gas regulator is essential for achieving accurate calibration results, protecting sensitive instrumentation and ensuring reliable gas delivery. The ideal regulator will depend primarily on two factors:
- The required gas flow rate
- The type of calibration gas being used
Step 1: Determine the Required Gas Flow Rate
The first step is to establish the flow rate required by your gas detection instrument or analyser.
Most instrument manufacturers specify an optimum calibration flow rate for their sensors, commonly:
- 0.5 L/min
- 1.0 L/min
Using the correct flow rate is important to ensure accurate sensor response and repeatable calibration results.
If your instrument contains an internal sampling pump or is connected to an automated calibration or docking station, an On-Demand Flow Regulator may be the preferred option. These regulators only deliver gas when a vacuum is created by the instrument, allowing the equipment to draw exactly the amount of gas required.
Benefits of on-demand flow regulators include:
- Reduced calibration gas consumption
- Improved gas utilisation
- Greater calibration accuracy
- Reduced operating costs
Step 2: Identify the Sensor Type and Calibration Gas
The type of gas being used will determine the appropriate regulator material of construction.
Selecting compatible materials is critical for maintaining gas stability, preventing contamination and maximising regulator service life.
Typical regulator materials include:
- Brass
- Nickel-plated brass
- Stainless steel
Corrosive and Reactive Gases
Highly reactive or corrosive gases require stainless steel regulators and wetted components to maintain gas integrity and prevent damage to the regulator.
Examples include:
- Chlorine (Cl₂)
- Ammonia (NH₃)
- Hydrogen Cyanide (HCN)
- Hydrogen Chloride (HCl)
- Nitric Oxide (NO)
- Nitrogen Dioxide (NO₂)
- Phosphine (PH₃)
Stainless steel regulators provide excellent corrosion resistance and minimise gas absorption or contamination, helping maintain calibration accuracy throughout the life of the cylinder.
For these applications, Oxford Valves strongly recommends the use of stainless steel regulators.
Avoid Using Brass Regulators with Corrosive Gases
Nickel-plated brass regulators should not be used with highly corrosive gases.
Over time, corrosive gas mixtures can attack the regulator internals, resulting in:
- Reduced regulator life
- Gas contamination
- Incorrect calibration readings
- Potential damage to sensitive instrumentation
Non-Corrosive Gas Applications
For non-corrosive gases and gas mixtures, brass or nickel-plated brass regulators are often suitable and provide an economical solution.
Typical examples include:
- Carbon Dioxide (CO₂)
- Carbon Monoxide (CO)
- Methane (CH₄)
- Nitrogen (N₂)
- Air
- Many hydrocarbon mixtures
These gases generally do not present compatibility concerns with brass-based regulator materials.
Selecting the Right Regulator
Choosing the correct regulator ultimately comes down to answering two simple questions:
- What flow rate does your instrument require?
- What gas or gas mixture will be used?
By selecting a regulator that matches both the flow requirements and gas compatibility, you can maximise calibration accuracy, extend equipment life and ensure safe, reliable operation.
If you are unsure which regulator is best suited to your application, the Oxford Valves team can assist with selecting the correct solution for your gas mixture, instrument and operating conditions.