Demand Flow vs Fixed Flow Calibration Gas Regulators
A demand flow calibration regulator supplies gas in response to the connected instrument's demand; a fixed flow regulator supplies a specified flow through its intended arrangement. The correct choice depends on the exact detector, cylinder, gas mixture and calibration instructions. An internal pump or a matching thread alone is not enough to establish compatibility.
This comparison helps you assemble the questions needed for an instrument and accessory enquiry. It does not prescribe a universal flow rate, connection method or substitute calibration procedure. Use the manufacturer's documented arrangement for the exact gas configuration.
Compare how gas is delivered
Calgaz's regulator specifications distinguish demand flow designs from fixed flow models. Demand flow equipment can respond to suction from an instrument pump, while fixed flow equipment provides a stated output under its specified conditions. The product-specific inlet, outlet, gas-contact materials and operating limits still need to match the task.
| Comparison item | Demand flow regulator | Fixed flow regulator |
|---|---|---|
| Basic delivery behavior | Responds to demand in the approved connected arrangement | Delivers a specified flow in its intended operating arrangement |
| Instrument question | Can this pump and connection operate with the specified regulator? | Does this instrument procedure specify this delivery rate and setup? |
| Other checks | Pressure limits, gas compatibility, connection and required accessories | Pressure limits, gas compatibility, connection and required accessories |
| Evidence that remains necessary | The actual detector's calibration instructions | The actual detector's calibration instructions |
These categories do not create a universal rule assigning one regulator to every pumped instrument and another to every diffusion instrument. Accessories, docking equipment and manufacturer procedures can differ. Compare the complete specified setup rather than the category label alone.
Distinguish field sampling from calibration gas delivery
A diffusion detector normally receives surrounding air at its sensor opening. Its calibration arrangement may use a specified cap and gas delivery assembly. A pumped instrument has a different normal sampling mechanism, but its calibration accessories and gas requirements still need to be documented.
Changing a regulator is not a method for converting a diffusion device into a validated remote-sampling system. Similarly, a pump that moves ambient air does not automatically tolerate any gas supply pressure. Keep the field-sampling specification and the calibration-delivery specification as separate entries in the enquiry.
If a proposed package includes an external pump, tubing, calibration cap or docking station, identify those parts explicitly. Request confirmation that the full arrangement is the one covered by the instrument instructions. A collection of individually plausible components is not sufficient compatibility evidence.
Match cylinder connection, pressure and gas-contact materials
RKI lists different regulator and cylinder connection options, illustrating why the cylinder interface must be checked. A threaded connection that appears similar does not resolve the regulator's pressure rating, flow behavior or compatibility with the gas being supplied.
Gas-contact materials can matter for reactive mixtures. The regulator manufacturer's specification should identify the gases and service conditions for which a model is intended. Do not transfer an accessory used for one mixture to another solely because both cylinders fit or both instrument displays use ppm.
Check the mixture concentration and balance gas required by the detector procedure, as well as the cylinder certificate and validity. The delivery path adds further components: tubing, filters, fittings and any specified vent or adapter. Their selection belongs in the documented arrangement, without improvising a pressure or flow adjustment.
Use actual instrument choices to frame the enquiry
| Instrument | Selected option | SKU | What to confirm |
|---|---|---|---|
| Diffusion single-gas CO option | Carbon Monoxide (CO) | GAS-NPLS-03 | Diffusion is documented; request its specified calibration cap and delivery arrangement. |
| Pumped single-gas CO option | Carbon Monoxide (CO) | GAS-Q7M4-03 | An internal micro pump is documented; confirm regulator and sampling compatibility from the manual. |
These two single-gas configurations provide a concrete distinction: one is listed as diffusion sampling and the other with an internal micro pump. Both links select CO, keeping the gas identity consistent while you compare the sampling format. Neither product entry alone establishes which regulator or calibration cylinder is supplied.
Ask for the model's current calibration instructions and an itemized package description. If an accessory is required, keep its part number and compatibility statement with the instrument SKU. The catalogue's choice of many gas variants should not be interpreted as evidence that one regulator is approved for all those gases.
Build a complete compatibility checklist
| Field | Evidence to request |
|---|---|
| Detector | Exact model, installed gas and calibration procedure revision |
| Gas mixture | Required target concentration, balance gas and certificate conditions |
| Cylinder | Connection type and the regulator's permitted inlet pressure |
| Delivery | Demand or specified fixed flow, with the approved connection arrangement |
| Contact materials | Compatibility with the named gas mixture |
| Accessories | Cap, tubing, fittings and any required adapter or docking equipment |
| Verification | Required checks and the record of the assembled configuration |
A useful quotation includes these answers rather than simply saying “gas regulator included.” Where a component or requirement is unresolved, get the supplier's documented answer before treating the package as ready for the intended procedure.
This comparison concerns selection and compatibility. Functional gas checks, calibration execution and cylinder handling should follow the supplied instructions and the site program. Regulator choice is one element of that process, alongside valid gas, a suitable instrument and a traceable record.
Frequently asked questions
Does every pumped detector need a demand flow regulator?
Use the specific manufacturer’s calibration arrangement. An internal pump alone does not establish the accepted regulator, connection or delivery setup.
Can one regulator be used for every gas?
Gas-contact materials, pressure range, connector and delivery requirements need to match each mixture and instrument. Do not assume universal compatibility.
Does a matching cylinder thread prove the setup is correct?
No. Thread compatibility is one requirement; flow behavior, pressure, gas compatibility and instrument instructions remain separate checks.
Related selection guides
- Define the response check or calibration task
- Compare field sampling methods
- Check the complete sampling path
Browse gas detector configurations to compare the current instrument options and their specified gases.
Contact us with the instrument model, gas option, cylinder mixture and the calibration arrangement you need to document. Regulator or calibration-gas supply is not established by the instrument product listing.
For reference only. Follow the instrument manufacturer's instructions and the applicable site assessment and procedures. Catalogue information is not evidence of suitability for every safety or process task.