Brand: Siemens

Siemens Maxum II FPD Hydrogen Restrictor Stainless Steel 2021388-004

Name: Siemens Maxum II FPD Hydrogen Restrictor 2021388-004
Brand: Siemens

Description

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.

Parameter	Specification
Model / Part Number	Hydrogen Restrictor, FPD, Stainless Steel, P/N 2021388-004
Function	Calibrated hydrogen fuel gas flow restriction to the FPD burner
Material	Stainless steel
Compatible Detector	Flame Photometric Detector (FPD)
Target Platform	Siemens Maxum Edition II Process Gas Chromatograph
Typical Total Hydrogen Flow (FPD II)	Approx. 100–130 mL/min (flame fuel plus carrier, if hydrogen carrier used)
Hardware Condition	New, genuine Siemens part number

Why Choose Seven Star LLC for FPD Fuel Gas Calibration Parts

Because the FPD’s hydrogen restrictor calibration depends on whether hydrogen or an inert gas is used as carrier, ordering the wrong restrictor from the broader Maxum II parts family – even one that looks identical to the correct one – can unbalance the flame chemistry and either prevent ignition or shift detector sensitivity. Seven Star LLC verifies the customer’s specific carrier gas configuration and detector setup before shipping this restrictor, rather than assuming a generic fitting will match. We also emphasize Siemens’ requirement that FPD gas supply lines stay extremely clean and sulfur-free, and help refinery and gas plant instrumentation teams across Oman keep correctly identified restrictor stock on hand for FPD troubleshooting, coordinating delivery across Muscat, Sohar, and the broader GCC.

Request a Quote for Siemens Maxum II FPD Hydrogen Restrictor Stainless Steel 2021388-004

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 availability and lead time, or confirm compatibility of the FPD Hydrogen Restrictor 2021388-004 with your specific Maxum II configuration, contact our instrumentation sourcing team today.

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About brand

Most Siemens automation parts are bought by article number, the string beginning 6ES7, 6AV2 or 6GK5 printed on every module. Founded in 1847 and headquartered in Munich, Siemens builds the SIMATIC controllers, SCALANCE networks and SINAMICS drives that plant engineers meet on almost every site. Seven Star LLC, an independent supplier, lists Siemens PLC and I/O modules, HMI panels, industrial Ethernet switches, drives, protection relays, temperature transmitters and gas analyzer spare parts for projects in Oman and the GCC.

Siemens product families on this page

Controller hardware covers the SIMATIC S7-1200 (CPU 1214C with SM 1223 signal modules) and the S7-1500 (CPU 1515-2 PN), with ET 200SP and ET 200M distributed I/O and their IM 155-6 and IM 153-2 interface modules. Operator panels include the KTP700 Basic and TP700 Comfort. SCALANCE XC208 managed switches handle industrial Ethernet. Drives are represented by the SINAMICS G120C compact inverter and the G120X for pumps and fans. From the power side come the SIPROTEC 7SJ85 feeder protection relay and SIVACON S8 switchboards, and from process instrumentation the SITRANS TH320 head-mounted temperature transmitter.

Where Siemens equipment is used

SIMATIC controllers and ET 200 I/O run packaged units, skids and whole process lines in water treatment, oil and gas, cement, food and manufacturing plants. SINAMICS drives control pumps, fans and conveyors, SCALANCE switches form the control network, and SIPROTEC relays protect medium voltage feeders and motors.

Ordering Siemens parts: what we need

Send the complete article number, the functional status or version printed on the module and, for CPUs, the firmware version your project was written for. For drives add power, supply voltage, filter option and fieldbus version. For SIPROTEC relays the long order number or product code is required, because it fixes the hardware and function package. A nameplate photo answers most of these points at once.

Frequently Asked Questions

What does this restrictor control?

It precisely restricts and meters the hydrogen fuel gas supply feeding the FPD burner, establishing the correct hydrogen flow rate for the detector's combustion flame.

How much hydrogen does the FPD typically require?

The FPD II typically requires approximately 100-130 mL/min of total hydrogen, combining flame fuel and carrier gas contributions if hydrogen is also used as carrier gas.

Is this restrictor the same as the FID hydrogen restrictor?

No, although part of the same Maxum II restrictor family, the FPD hydrogen restrictor is calibrated differently from the corresponding FID restrictor, so correct part selection matters.

Why is stainless steel used for this restrictor?

Stainless steel keeps the restrictor's internal flow-path geometry dimensionally stable and corrosion-free, preserving the precise hydrogen flow the flame chemistry depends on.

Does Seven Star LLC supply this part across the GCC?

Yes, Seven Star LLC sources and supplies the Siemens Maxum II FPD Hydrogen Restrictor 2021388-004 to refinery, gas processing, and petrochemical customers across Oman and the wider GCC region.

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