Siemens Maxum II FPD Hydrogen Restrictor Stainless Steel 2021388-004

Overview: Precision Fuel Gas Control for the FPD Flame

The Siemens Maxum II FPD Hydrogen Restrictor, part number 2021388-004, is a stainless steel tube assembly that precisely restricts and meters the hydrogen fuel gas supply feeding the Flame Photometric Detector (FPD) burner on the Siemens Maxum Edition II process gas chromatograph. The FPD combusts sample components in a hydrogen-rich flame to generate the characteristic sulfur-emission light the detector measures, and this restrictor’s calibration is what establishes the correct hydrogen flow rate for that flame – a rate that, when the FPD uses hydrogen as carrier gas rather than nitrogen, helium, or argon, is adjusted downward since additional flame-fuel hydrogen is then reduced.

As an independent specialized supplier of Siemens Maxum Edition II analyzer spare parts, Seven Star LLC sources and supplies the FPD hydrogen restrictor 2021388-004 to refineries, gas plants, and petrochemical complexes across Oman and the wider GCC. Because hydrogen flow calibration is directly tied to flame stability, Seven Star LLC helps maintenance teams keep the correct genuine restrictor in stock for FPD servicing.

Working Principle: Calibrated Fuel Gas Restriction

The restrictor works by presenting a precisely sized internal flow path to the hydrogen fuel line, creating a defined pressure drop that sets the hydrogen flow rate delivered to the FPD burner’s outer annular gap for a given upstream supply pressure. This hydrogen flow mixes with combustion air from the burner’s inner annular gap to sustain the flame in which sample sulfur compounds are combusted, and the ratio between hydrogen fuel and combustion air directly governs whether the flame ignites reliably and how sensitive the resulting photometric signal will be.

Because the FPD’s overall hydrogen requirement (approximately 100–130 mL/min for the FPD II, combining flame fuel and carrier gas contributions) depends on whether hydrogen or an inert gas is used as carrier, the restrictor’s fixed calibration is specified for a defined configuration, and substituting a restrictor from a different calibration point in the parts family can unbalance the flame chemistry even though the fitting may look identical.

Engineering Design of the Restrictor

The 2021388-004 restrictor is machined to the specific flow-calibration dimensions required for FPD hydrogen fuel service, distinct from both the FPD combustion air restrictor and the equivalent restrictors calibrated for the FID detector family. Stainless steel construction keeps the restrictor’s internal flow-path geometry dimensionally stable and corrosion-free over long service life, protecting the precision the flame chemistry depends on.

As with all components in the FPD gas supply path, Siemens specifies that gases and supply lines feeding this highly sensitive detector must be kept extremely clean and sulfur-free to maintain a strong signal-to-noise ratio, making correct restrictor selection and clean installation practice important during any FPD gas-path servicing.

Key Features

The FPD Hydrogen Restrictor 2021388-004 delivers the precise fuel gas calibration the FPD flame depends on. Key characteristics include:

• Stainless steel construction for corrosion resistance and dimensional stability over long service life.
• Precisely calibrated flow restriction specific to FPD hydrogen fuel requirements.
• Directly affects flame ignition reliability and photometric detection sensitivity when correctly installed.
• Distinct calibration from the corresponding FID hydrogen restrictor within the same parts family.
• Genuine Siemens Maxum II part number for correct fit and flame stoichiometry.

Industrial Applications

The FPD hydrogen restrictor is a required component wherever a Maxum Edition II analyzer is configured with a Flame Photometric Detector for sulfur-selective analysis, including natural gas sulfur specification testing and refinery sulfur recovery unit monitoring. Because it directly governs flame fuel supply, it is checked and, where necessary, replaced during FPD troubleshooting when ignition reliability or sensitivity issues are reported.

Seven Star LLC supports refinery instrumentation teams, gas processing operators, and petrochemical maintenance departments across Oman, Muscat, Sohar, and the broader GCC region with sourcing of this and other Maxum Edition II FPD gas-path hardware, helping analyzer houses maintain reliable sulfur-selective detection.

Technical Specifications

The table below summarizes the core specifications of the Siemens Maxum II FPD Hydrogen Restrictor as supplied by Seven Star LLC.

Call To Action

Seven Star LLC is a dedicated supplier of Siemens Maxum Edition II process gas chromatograph spare parts and FPD gas-path hardware throughout Oman and the GCC. To request a formal B2B quotation, verify current stock availability, or confirm compatibility of the FPD Hydrogen Restrictor 2021388-004 with your specific Maxum II configuration, contact our instrumentation sourcing team today.