Fixed-flow calibration gas regulator: the preset-orifice regulator that feeds span gas from a C-10 cylinder to a gas detector or analyzer
Constant-flow regulators for disposable calibration cylinders · preset 0.25, 0.5 or 1.5 L/min · C-10 (5/8 in-18 UNF) inlet · nickel-plated brass vs. stainless steel for reactive gases · when a pumped detector needs a demand-flow regulator instead
A fixed-flow calibration gas regulator sits on a small disposable cylinder of span gas and lets out one flow rate set at the factory, so a technician can bump-test or calibrate a portable gas detector or feed an analyzer without adjusting anything. Three choices decide whether it suits: the flow the detector maker calls for, the cylinder valve thread, and a body and seal material that will not absorb or react with the test gas. Pumped instruments raise a fourth question, whether a fixed flow is right at all.
Fixed-flow (constant-flow) regulators for disposable calibration gas cylinders, with a preset flow, a cylinder contents gauge and an on/off valve, used to deliver span gas to portable gas detectors, fixed detectors and analyzers; demand-flow regulators are compared. Adjustable pressure-reducing regulators are covered on the Pressure regulator page, instrument needle valves on the Needle valve page, and electronic flow control of process gases on the mass flow controller pages. Hydraulic and pneumatic flow control valves and medical infusion flow regulators are outside this page.
CNFX editorial research · Sources checked October 19, 2026 · 5 sources
0.25, 0.5 or 1.5 L/min, or a demand regulator for a pumped detector
MSA states that 0.50 L/min is the market standard flow for calibration gas, but that its diffusion-based detectors are designed to work at 0.25 L/min, so it supplies 0.25 L/min regulators for them; it also lists a fixed-flow Model R at 1.5 L/min. For pumped instruments MSA recommends its Gas Miser demand regulator, which supplies the flow the instrument pump draws and shuts itself off when not in use, so no on/off valve is needed. [1]
A fixed-flow regulator therefore has to be bought to the flow the detector manufacturer names. Forensics Detectors calls 0.5 L/min "A commonly recommended flow rate used for gas detector calibration" [2], and the Viking units are factory calibrated to deliver 0.5 L/min [3][4]; neither listing states a flow tolerance, so ask for one.
Editorial calculation: at 0.5 L/min, a 58 L disposable cylinder of the size Viking lists runs for 58 / 0.5 = 116 minutes of open flow, and a 34 L cylinder for 68 minutes; at MSA's 0.25 L/min both times double. Gas left below the regulator's working inlet pressure is not counted, so real run time is shorter. [3][1]
Give the supplier the detector model and whether it is diffusion or pumped, the flow its manual specifies and the cylinder sizes used, and ask for the flow tolerance and the inlet pressure below which the preset flow is no longer held.
02
C-10 cylinder thread, brass or stainless body, and the gases each will carry
The listings reviewed all use the C-10 cylinder connection, given as 5/8 in-18 UNF. Forensics Detectors' 0.5 L/min regulator is nickel-plated brass with a 1,500 psi gauge, a 6 mm hose barb, 3.3 × 1.7 × 1.6 in and 15 oz, and is listed for reactive and non-reactive gases. [2]
Viking sells two 0.5 L/min single-stage versions for 34, 58, 60 and 103 L disposable cylinders, each with gauge and on/off valve: a nickel-plated brass one for non-reactive gases plus the reactive gases H2S and SO2, and a stainless steel one described in one place as "supporting mostly reactive gases" and in its specification list as suitable for all non-reactive and reactive gases. Both carry a 24-month warranty with the OEM recommending replacement after two years of service. [4][3]
Forterra lists stainless constant-flow regulators for aluminium cylinders with C-10 valves, maximum inlet 2,175 psi (150 bar), and flows of 500 mL/min on its CFR-500 page and 250 mL/min on its CFR-1500 page. Its maximum outlet entries read "500psi (3-4bar)" on one page and "50psi (3-4bar)" on the other; 3–4 bar is about 44–58 psi, so the 500 psi figure and the bar figure cannot both be right, and the outlet pressure should be confirmed with the maker. [5]
1 company lists this product among what they make. Company figures are quoted from each
company's own website; every card states where the relationship came from.
Qingdao Forterra Gas Co., Ltd.
Manufacturing site to be confirmed for the order
Lists stainless constant-flow regulators for C-10 calibration cylinders, 250 and 500 mL/min, 150 bar maximum inlet.
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Compiled and source-reviewed by the CNFX editorial team.
Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review
· Page last updated 19 October 2026
Buyer questions
What flow rate should a calibration gas regulator have?
The one the detector maker specifies. MSA calls 0.50 L/min the market standard and uses 0.25 L/min for its diffusion detectors. [1]
Can a fixed-flow regulator be used with a pumped gas detector?
MSA recommends its demand regulator for pumped instruments, as it supplies the flow the pump draws. [1]
Is a brass regulator suitable for H2S?
Viking lists its nickel-plated brass 0.5 L/min regulator for non-reactive gases plus H2S and SO2, and a stainless version for reactive gases. [4][3]
Sources and what still needs a direct check
Sources checked 2026-10-19. MSA's regulator page for flow choice and demand regulators; product data from Viking, Forensics Detectors and Forterra for threads, materials, flows and pressures.
