Häufig gestellte Fragen (FAQ)

An SNG system consists of several coordinated components. Tanks store the propane and are equipped with a filling line and a transfer station. A hot-water or electrically heated vaporiser converts the liquid propane into the gas phase. The gas/air mixing system from LT GASETECHNIK adjusts the gas mixture to match the calorific value of the existing natural gas. A buffer vessel can compensate for large fluctuations in gas demand.

Overall, the design allows the flexible use of propane to supplement or fully replace natural gas in the range of 1 to 100 MW as required. The additional option of blending hydrogen or green LPG (bio-propane, rLPG) enables a positive environmental impact.

The space requirement of an SNG system depends on the plant size and safety requirements. An overview of the main components and their footprint:

• Tanks: Installation pad or dome pit, depending on storage capacity
• Unloading station: For tanker trucks with fill and vapour return connections
• Vaporiser and pressure regulation station: Often in a 20-foot container on a suitable foundation
• Gas/air mixing system: Depending on gas volume, in a field cabinet, on a frame or in a 30-foot container

When planning, space should be allocated for access, maintenance and safety clearances. The exact area is determined individually according to local conditions.

For liquefied gas vessels with a storage capacity of 3 tonnes or more, an approval procedure under the Federal Immission Control Act (9. BImSchV) is required. For a 29-tonne vessel (≥ 9 t and < 30 t), a simplified procedure without public disclosure applies. For a 165-tonne vessel, a formal procedure with public disclosure is required. In general, TRBS 3146 applies to stationary pressure systems, as well as the hazard assessment in accordance with BetrSichV and GefStoffV.

The formal approval period is seven months after a declaration of completeness, but realistically at least 12 months. For amendment approvals to existing systems, four to six months are theoretically envisaged.

Important: From 50 tonnes of propane storage, the Major Accident Ordinance (Störfallverordnung) applies, which entails additional documentation and inspection obligations, regardless of other accident-relevant substances on site. For questions about approval procedures, the weyer gruppe is available to assist.

Without a pump and vaporiser, an externally installed tank typically only achieves 0.75 – 1.5 barg, which is insufficient for the standard gas mixing system that requires a minimum inlet pressure of 4.5 barg. The pump transports the liquefied gas in the liquid phase to the vaporiser, which is designed for a maximum of 25 bar and, with a redundant safety device, prevents liquid phase from entering the downstream piping system.

The gas outlet temperature of the vaporiser is generally between 40 °C and 80 °C to avoid condensation in the piping system. Vaporisers must be equipped with a pressure switch, heating shut-off and safety valve. If there is a longer run to the gas mixer, trace heating must be provided to prevent droplets from damaging the fittings. At the gas mixer, temperatures between 25 °C and 60 °C should be present.

A gas mixing system is used to avoid converting existing burners and to allow existing equipment to continue to be used unchanged. The reason: propane has a significantly higher calorific value of 25.48 kWh/m³ compared to natural gas (L-gas: 8.87 kWh/m³, H-gas: 10.475 kWh/m³). Existing industrial burners therefore cannot process pure propane.

In a gas mixing system, the propane is blended with air or nitrogen to match the calorific value of natural gas – the result is SNG (Synthetic Natural Gas). This natural gas substitute can be fed directly into the plant network without the need to retrofit burners. This avoids downtime caused by cooling down, conversion and reheating. In addition, a gas mixing system enables the use of further energy sources such as hydrogen or green propane.

Gas mixing systems from LT GASETECHNIK operate with high precision and reproducibility. Since gases cannot be mixed precisely simply by adjusting two valves, the systems use the physical laws of nearly ideal gases: the pressures and volumetric flow rates (quantities) of each individual gas are controlled, back-mixing is prevented, and the gases are blended via a turbulence element.

Static SNG gas mixers from LT achieve accuracies of ±0.5 vol.% or better.

Dynamic SNG gas mixing systems achieve accuracies of up to ±0.1% of the setpoint. This level of precision requires a gas analyser with cascade feedback and regular calibration with certified reference gases.

Various technologies are available for producing gas mixtures, differing in accuracy and degree of automation:

• Mechanical proportional mixing valve: Outdated, inaccurate, unsafe – manual interventions required, slow start
• Electronic mixing valve: Like mechanical, but with motorised actuation
• Pneumatic mass flow controllers: Accurate, but manual interventions necessary
• Mass flow controllers (MFC) or orifice measurement with control valves: Very accurate, fully automatic adjustment, fast start – the technology preferred by LT GASETECHNIK for dynamic gas mixers

LT GASETECHNIK uses exclusively the latter two, modern technologies.

Gas mixing systems from LT GASETECHNIK feature comprehensive safety functions tailored to the respective application:

• Gas backflow prevention: Mechanical or control-based, to prevent unwanted transfer between gas streams
• Safety relief and safety shut-off valves (SBV/SAV): To protect against excess pressure
• Gas analysis: Permanently monitors the gas mixture to prevent impermissible compositions (e.g. explosive gas)
• Pressure and volume control: Precise regulation of operating parameters
• Documentation: Complete recording of temperatures, gas flows and mixing results
• Automatic control: Integration into higher-level process control systems possible

LT GASETECHNIK offers various concepts for natural gas substitution, graded in performance – from the compact gas mixer to the complete gas mixing system. For standard applications, a selection of 72 standard gas mixer models is available, enabling fast delivery. Above a certain performance class, the design of a customer-specific gas mixing system is required, which means a greater time requirement for engineering and manufacturing.

Further information on LT gas mixers can be found on our product page.

LT GASETECHNIK has been manufacturing gas mixers and gas mixing systems for hydrogen for over 50 years. Green hydrogen can be blended into natural gas or SNG in a gas mixing system – up to 20%, and in some cases even up to 30% H₂ in the gas mixture, can usually be processed without problems by current burner and pipeline installations. LT has also delivered systems with up to 100% hydrogen content.

For industrial companies, the gradual transition represents an energy flexibility gain: in addition to improved supply security, it offers opportunities for price optimisation between the energy carriers hydrogen, natural gas and propane. The significantly lower calorific value of hydrogen (2.995 kWh/m³) is compensated by blending with propane and air or nitrogen.

SNG systems from 5 MW are usually designed with the “H₂-ready” option, enabling a later conversion to propane/hydrogen/air blending.

SNG systems from 400 Nm³/h can be supplied with the “H₂-ready” option, which enables later conversion to hydrogen blending. During conversion, the system is modified at LT GASETECHNIK for a limited period of approximately 2 weeks and then reconnected to the plant network.

The space already provided at the time of initial delivery for additional fittings and control components is used. The analyser technology is extended to include H₂ measurement, and a Wobbe-index control for the gas mixture of propane, hydrogen, natural gas and air is integrated. In total, LT GASETECHNIK has realised 250 customer-specific gas mixing systems worldwide, approximately 90 of which include H₂ blending.

Yes, standard natural gas burners can process a gas mixture of propane/air or propane/nitrogen without problems. The flame shape changes slightly, as the combustion gas volumetric flows are different, but the energy input into the process remains identical to the previous natural gas operation, as calculated by the calorific value.

For processes that depend on a specific flame shape (e.g. flame length or temperature distribution in flame polishing), LT GASETECHNIK offers special solutions. Pure propane without blending is not suitable for typical burners – retrofitting usually requires a downtime of several days and corresponding hardware from the burner manufacturer. Using a gas mixing system avoids exactly this conversion.

For the mixing of propane with air, LT GASETECHNIK recommends a SIL-2 oxygen gas analyser with SIL-2 shutdown. This solution monitors the oxygen content in the mixed gas continuously and independently of the gas mixer control, and automatically shuts down if a limit value is exceeded. This reliably prevents the formation of explosive gas mixtures in the plant network.

At smaller outputs up to 120 Nm³/h, nitrogen is sometimes used as the blending gas, as this does not require special SIL monitoring, making the system simpler and more cost-effective.

Back-mixing – i.e. the unwanted ingress of air into the propane line or vice versa – is prevented by several measures. For smaller systems, gas backflow preventers are used. For systems from 400 Nm³/h, check valves are used. The control system monitors the pressures downstream of the pressure regulators and automatically closes the valves in the event of unfavourable differentials, while an alarm is triggered. In addition, the closing pressure of the pressure regulators is below the minimum supply pressure, so that backflow is structurally excluded.

Yes, if the natural gas supply is completely shut off, the SNG backup system can fully replace the natural gas. In the event of a partial shutdown, SNG is fed into the existing plant natural gas network to partially replace the missing natural gas – a process known as peak shaving.

Partial replacement requires careful coordination, as the pressure stages of plant networks are finely tuned and the natural gas supply must be flow-controlled. Where necessary, the backup solution consists of three controlled streams: propane, air or nitrogen and natural gas, enabling precise setting of quantities and pressures and verification of the permitted reduced consumption.

LT gas mixing systems have special quick-start capabilities that make them particularly suitable as a backup solution. From standby, the system delivers the correct gas mixture and gas quantity in under one minute. For a cold start after complete shutdown of the vaporiser and gas mixing system, the start-up time is approximately 30–45 minutes for hot-water vaporisers and approximately 10–20 minutes for electrically heated vaporisers.

This makes SNG systems suitable both as a reliable emergency supply in the event of natural gas interruptions and for peak load coverage (peak shaving). With static gas mixers with a buffer vessel, correctly mixed gas is also immediately available after switching on.

LT GASETECHNIK offers comprehensive consulting and support throughout the entire investment process. As part of the weyer gruppe, we work with established partners and offer, among other things:

• Approval support
• Safety concepts and explosion protection
• Engineering and process technology for conceptual planning
• Gas mixing technology has been our core business for over 50 years

This means you can receive a complete solution from a single source, or support for individual packages, as required.

LT GASETECHNIK focuses on gas mixing systems and therefore does not submit offers for tanks, vaporisers, liquid pumps or gas supplies. However, we are happy to recommend partner companies so that you can receive a complete solution from a single source if desired.

Commercial propane in accordance with DIN 51622 in 95/5 quality (minimum 95% propane, maximum 5% butane) is the common fuel gas for industrial gas mixing systems. Pure propane is only used in industrial applications for specific purposes. LPG (Liquefied Petroleum Gas) is used as a synonym.

rLPG, or renewable propane (also bio-LPG or bio-propane), is biogenic liquefied gas from waste, biomass or renewable raw materials, chemically identical to conventional LPG. It meets strict certifications with evidence of origin, quantity and CO₂ reduction (between 15 and 100%), is GEG-compliant and low-emission to CO₂-neutral. Available in Germany from many suppliers, often as a blend (15–100% bio content); sufficient supply long-term through increasing production. Price is approximately 10–75 cents/litre above conventional LPG (depending on bio content), with exemption from CO₂ levies.

LNG (Liquefied Natural Gas) and CNG (Compressed Natural Gas) usually do not require a gas mixing system.

If hydrogen (H₂) at 20% is planned for injection into the internal gas supply network, the limits of the burners, process plants and materials must be checked. Based on current knowledge, standard burners can process up to 20% H₂ in the gas mixture without problems – however, this must be assessed on a plant-specific basis. Special burners are suitable for up to 100% H₂, but are considerably more expensive and require burner replacement.

As up to 20% H₂ in the natural gas network may be permitted in the future, an H₂ gas analysis prior to blending or of the H₂ content in the gas mixture is advisable: this allows the already existing hydrogen content to be taken into account and the gas mixture to be set precisely to the desired total content.

In a pressure-controlled gas mixing system, the outlet pressure is set to a fixed value, and the gas quantity automatically adjusts to the current consumption. An SNG system operates in a similar way to a natural gas supply and keeps the pressure in the plant network constant. If consumption falls, the mixing system reduces the delivery quantity; if it rises, it increases accordingly.

In a flow-controlled SNG system, on the other hand, a fixed gas quantity is produced, and the pressure is set via the gas pressure regulation and metering station (GDRM) with natural gas. This variant is particularly suitable when a defined quantity of natural gas substitute must be verified.

The choice between the two concepts depends on the operating mode and the requirements of the plant network. We are happy to advise you on the optimal control strategy.

Propane consumption can be derived from the natural gas consumption to be replaced. A practical example: at 1,000 Nm³/h of natural gas with a calorific value of 11.5 kWh/m³, this results in a propane consumption of approximately 900 kg/h. In 24/7 operation, this corresponds to a daily consumption of approximately 22 tonnes.

Since a semi-trailer has a capacity of just under 20–21 tonnes, this example would require daily filling of a 29-tonne vessel. From a daily consumption of approximately 100 tonnes (approximately five times the quantity), a rail connection with tank wagons becomes essential.

Important: During refilling, gas mixture production and therefore burner supply can continue uninterrupted. Logistics planning should be carried out jointly with the tank and gas supplier.

Nitrogen as a blending gas is particularly worthwhile for smaller systems up to 120 Nm³/h of gas mixture or for temporary backup operation. The advantage: no SIL-2 oxygen monitoring with associated shutdown, and no additional compressed air is required, making the system simpler and more cost-effective. The annual SIL circuit verification costs are also eliminated.

As a rule of thumb for determining nitrogen requirements: approximately 40% of the required total volumetric flow at an inlet pressure of at least 4.5 barg at the gas mixer. Compressed air is preferred for larger systems, as it is easier and more cost-effective to supply in large quantities – but then requires a compressed air quality according to ISO 8573 (quality class 2:4:1) with a dew point below –25 °C.

Some companies consider using butane in summer and commercial propane in winter, as butane can be seasonally cheaper. LT GASETECHNIK can design gas mixing systems accordingly. However, pure butane operation requires adjustments: the flow measurement must be switched to Coriolis technology, the lower vapour pressure of butane makes a pump essential, and the trace heating must be designed for the higher required temperature. With seasonal changeover and mixing of both gas types in the tank, manual interventions may become necessary.

An SNG system offers several levers for CO₂ reduction. By using renewable LPG (rLPG, also known as “green propane”), CO₂ emission certificates can be saved. The option to integrate green hydrogen into the gas mixture further reduces the fossil fuel share. In addition, flexible fuel design – switching between natural gas, propane and hydrogen depending on availability and price – enables gradual decarbonisation without the need to completely retrofit existing systems.

In most cases, yes. The SNG gas mixture of commercial propane (DIN 51622, 95/5 quality) and air or nitrogen is blended in a ratio of approximately 72/28 (depending on calorific value). All components of the gas mixture, with the exception of oxygen when air is used, are also found in natural gas. At the burner, oxygen and nitrogen are added to the combustion air anyway.

On careful inspection, in addition to the burners and thermal process equipment, the pipeline materials, fittings and elastomers of the supply network should also be checked. LT GASETECHNIK assumes that existing installations are generally suitable, but this must be assessed on a plant-specific basis by the operator.

A gas mixer with its own gas supply is in most cases significantly cheaper than purchasing pre-mixed gas in cylinders or bundles. In metal processing in particular, customers specifically use various process gases – such as nitrogen and argon for inerting, hydrogen for reduction or CO₂ for specific thermal reactions.

In addition, an in-house gas mixer enables flexible adjustment of gas composition to changing production requirements. With a precise gas mixer from LT GASETECHNIK (accuracy ±0.5% or ±0.2%), savings of up to 30% on blending gas costs can be achieved, as the safety margin can be smaller than with less accurate systems.

LT GASETECHNIK offers three gas mixer series with different performance profiles:

Performance:

• smart: 15, 50, 100 Nm³/h
• comfort: 15, 25, 50, 100, 200, 300, 500 Nm³/h
• advanced: 3 to 150 Nm³/h

Maximum operating pressures:

• smart: 10 bar(g)
• comfort: 25 bar(g)
• advanced: 10 bar(g)
• individual: from 50 millibar(g) to 100 bar(g) as required

Control and accuracy:

• smart and comfort: Manual setting, reproducibility ±0.5%
• advanced: Electronic control with PLC, touchscreen and IoT options, reproducibility ±0.2%
• System engineering: Siemens control, reproducibility ±0.1%

Recommendation by requirement:

• Highest accuracy or low pressure drop → advanced
• Cost-effective and simple maintenance → smart / comfort
• IoT connection or remote control → advanced

All details can be found in the gas mixer type comparison overview.

A static gas mixer (types smart and comfort) produces a constant mixed gas quantity that is set manually. Since the quantity produced is slightly above consumption, the pressure in the buffer volume rises. When the upper pressure point is reached, the mixer switches off and restarts when the lower pressure point is reached. Accuracy is guaranteed at ±0.5 vol.%. Adjustments are made manually via metering valves; temperature-related deviations must also be corrected manually.

A dynamic gas mixer (type advanced) is operated via an electronic control system and automatically adjusts quantity and concentration. It delivers exactly the quantity consumed at constant pressure – with a guaranteed accuracy of ±0.2 vol.%.

Both systems can be configured with or without buffer vessels, redundantly with automatic switchover (electronic and/or pressure-controlled).

The high mixing accuracy of LT gas mixers is based on a superior technical concept. While some competitors use a single proportional valve, LT uses per gas line a dome pressure regulator, a calibrated variable area flow meter and a precise metering valve plus a dynamic pressure valve. This achieves inlet pressure independence – even with pressure fluctuations of over 3 bar.

For dynamic gas mixers, LT controls via temperature- and pressure-compensated mass flow controllers or orifice measurement with control valves. The result: ±0.5% for static and ±0.2% (in special cases ±0.1%) for dynamic gas mixers – guaranteed. Field experience frequently shows twice the accuracy.

The top 5 advantages of LT gas mixers at a glance:

1. Highest mixing accuracy: ±0.5% or even ±0.2% guaranteed – saves blending gas costs
2. Low total operating costs: Low running costs thanks to robust, long-lasting design
3. Long-lasting design: Gas mixer types comfort and smart last over 25 years – a legendary example is a gas mixer from 1972 that worked reliably for 22 years without any maintenance whatsoever, for almost 200,000 hours
4. Simple maintenance: Good accessibility of all components, no special tools required
5. Comprehensive automation: IoT connectivity, remote control, recipe management and data logger available as options
   

With a precise gas mixer from LT GASETECHNIK, savings of up to 30% on blending gas costs are achievable. The calculation is straightforward: a conventional gas mixer with ±2% accuracy requires a larger safety margin on the setpoint. For a minimum content of 5% H₂ in N₂, the setpoint would need to be set at 7.5%. The actual average consumption would then be 7.5% instead of the required 5.2%.

An LT gas mixer with ±0.2% accuracy allows a setpoint of just 5.3% – the difference of 2.25% saves 30% hydrogen. For a gas mixer with 500 Nm³/h and 8,500 operating hours per year, this results in savings of approximately €50,000 per year. The higher investment in an LT high-tech gas mixer therefore typically pays back in less than one year.

The short designation of LT series gas mixers follows a systematic structure: GMx LLL-X-B-A Type. Here “GM” stands for non-flammable gases and “GMB” for flammable gases. “LLL” indicates the performance in Nm³/h, “X” the number of gases to be mixed, “B” identifies the buffer vessel (E = stainless steel, C = carbon steel) and “A” stands for an integrated gas analyser. The type follows at the end: smart, comfort or advanced.

Examples: GM 50-2 smart = gas mixer for two non-flammable gases, 50 Nm³/h, type smart, without buffer and analyser. GMB 100-3-E-A comfort = gas mixer for three gases (at least one flammable), 100 Nm³/h, with 90-litre stainless steel buffer vessel and gas analyser, type comfort. This nomenclature facilitates quotation preparation and comparison.

Yes, LT gas mixers are specifically designed for later adaptation. If gas quantities or mixing ratios change, it is often sufficient to replace a single gas train or just individual components, at a fraction of the price of a new gas mixer.

A practical example: to adapt a gas mixer from 18% CO₂ (balance argon) to 2.5% CO₂, only the CO₂ flow meter needed to be replaced. Another example: to double the performance of a 50 Nm³/h gas mixer to 100 Nm³/h, only the flow meter and metering valve were replaced on one gas train. This flexibility is not available with proportional valve gas mixers. In both cases, a competitor’s product would have required a new gas mixer.

When comparing gas mixers from different manufacturers, caution is advised as performance specifications are not directly comparable. With some competitors, the rated performance refers to the volume in air, not to the actual mixed gas. The actual mixed gas performance must be calculated using a gas-specific conversion factor and is often significantly lower.

With LT gas mixers, the stated performance always refers to the actual maximum achievable mixed gas output in Nm³/h (usually plus an undisclosed performance reserve) – regardless of inlet and outlet pressures within the design limits. In addition, gas filters, EMC declaration of conformity and operating instructions are already included as standard in LT gas mixers. The additional inlet pressure reduction, which often has to be sourced separately from competitors (approx. €1,000 for two gases), is also eliminated with LT thanks to the integrated dome pressure regulators.

The mechanical part of LT gas mixers is “technically permanently leak-tight” in accordance with TRBS 2152 Part 2 and does not generate an Ex zone. However, the electrical part (control system and gas analysis) must not be installed in the hazardous area. Installation options in detail:

• Types smart, comfort and advanced: Mechanical part can be installed in an Ex area – gas analyser and possibly control system must be mounted separately outside
• Gas mixing systems (often in a container or on a frame): Mechanical and electrical parts are separate; the mechanical part is designed for the Ex area

Special solutions for the Ex area with high accuracy are available in various options.

All LT gas mixers up to 1,000 Nm³/h are available with and without buffer vessels. Without a buffer, the gas mixer type comfort is designed for wall mounting (1,000 × 800 × 400 mm). With a buffer vessel, the types smart, comfort or advanced stand on the floor (typically: 1,600 × 800 × 400 mm).

As a rule of thumb for buffer size: 10% more buffer volume in litres than the gas mixer performance in Nm³/h.

The type advanced (dynamic gas mixer) usually does not require a buffer tank, as it automatically adjusts the quantity at constant pressure. However, the advanced gas mixer is also available with a buffer for special applications.

Buffer vessels are available as standard from 90 litres to 1,000 litres.

Advantages of the buffer tank:

• Compensation of consumption fluctuations
• No continuous gas withdrawal required
• Immediate availability of correctly mixed gas after switching on

Disadvantages:

• Annual inspection obligation
• Higher costs
• Delay when changing the mixing composition
  

The power supply for LT gas mixers is straightforward. Typical requirements: L/N/PE AC 50/60 Hz, 230 V (±10%), power consumption e.g. 23 VA. Larger gas mixing systems from 400 Nm³/h may require a higher power connection depending on the scope of control and additional components such as gas preheaters or trace heating. The exact requirements are determined during project engineering.

The standard enclosures of LT gas mixers are fundamentally suitable for outdoor installation. They consist of a painted steel cabinet with a lockable door and inspection window, dust- and splash-proof to protection class IP 54. However, they should be protected from rain and snow – a roof overhang or simple canopy is recommended.

For operation at sub-zero temperatures, an internal cabinet heater can optionally be integrated. Larger gas mixing systems (from 400 Nm³/h) are often installed in insulated containers with separate cooling and heating for the electrical part. The advanced type is usually only suitable for outdoor installation with heating, while the smart and comfort types can be installed outdoors without problems with customer-provided weather protection.

Please provide us with the ambient temperatures and gas temperatures so that we can offer the most suitable solution.

The customer typically undertakes the following tasks during installation:

• Transport of the gas mixer from the handover point to the installation site
• Provision of the installation site and erection of the system
• Laying of power and data cables
• Piping and connection of media supply and return lines
• Provision of gases and electricity including calibration gases (if a gas analyser is installed)
• Where applicable, laying of vent and condensate lines

Some of these items can be provided by LT upon agreement.

LT GASETECHNIK provides detailed connection drawings and an interface list on request.

For gas mixing systems, the control is mounted in a separate control cabinet and is usually equipped with a local operating device (touchscreen) and a connection to the central control system. LT GASETECHNIK prefers LT standard or Siemens S7 controllers. Fail-safe solutions are also available.

As an alternative to the expensive Siemens solution, we offer proven industrial controllers from an alternative manufacturer for smaller tasks. LT uses these over 100 times per year across various gas technology projects. Wiring on terminal blocks is also possible for actuation via a higher-level process control system (PCS).

Yes, optimisations typically take place a few weeks after regular operation begins, or immediately after commissioning if required. The control strategies are reviewed and the stability and speed of the control loops optimised. Transition processes and overshoot behaviour are also analysed and minimised.

These optimisations can be carried out either remotely via a VPN connection or on-site by LT GASETECHNIK.

Normal operation of a gas mixer is continuous. At low consumption (below approximately 10% of the maximum mixed gas output), the mixer automatically switches to intermittent operation – the cycling frequency depends on the available buffer volume and the current gas consumption.

Minimum run times between switching on and off differ depending on the type:

• smart and comfort: At least 10 seconds per operating cycle
• advanced: At least 1 minute per operating cycle
• Gas mixing systems: Depending on the individual concept, typically continuous

With a buffer tank, static gas mixers typically operate intermittently; without a buffer tank, continuously.

Yes, the set gas mixing ratio remains unchanged after switching off and back on. With static gas mixers (smart and comfort), the metering valves are set purely mechanically and retain their position. The advanced type additionally offers the option of storing various recipes in the control system, so that different gas compositions can be recalled at the touch of a button.

The time to a qualified, stable gas mixture depends on the gas mixer type:

• smart and comfort: After setting, re-adjustment takes a few minutes, depending on the qualifications of the operating staff
• advanced and gas mixing systems: Immediately after switching on – the electronic control automatically establishes the desired composition

For SNG gas mixing systems with quick-start function, the correct gas mixture is available from standby in under 1 minute. A cold start with hot-water vaporisers takes approximately 30–45 minutes, with electrically heated vaporisers approximately 10–20 minutes.

With LT gas mixers, the inlet pressures of the various gases do not need to be kept within less than 3 bar pressure differential, unlike competitor products. LT gas mixers use pressure regulators on each gas inlet line that reliably compensate for even large pressure differences.

LT gas mixers for nitrogen/hydrogen applications feature a multi-stage safety concept: dome pressure regulators in the gas inlet lines are controlled by the carrier gas (nitrogen) and are normally closed. In the event of carrier gas failure, this reliably prevents impermissible hydrogen enrichment.

In addition, a normally-closed valve is installed in the mixed gas outlet line, which, together with the dome pressure regulators, provides double safety. The advanced type is also equipped with a gas detection device that automatically shuts down in the event of a leak.

LT gas mixers offer extensive networking capabilities. Standard (where a control system or gas analyser is integrated): potential-free contacts, digital inputs/outputs, relay outputs, analogue inputs (0–10 V / 4–20 mA), Ethernet and USB connection with data logger.

Optionally available: Modbus RTU, CANopen, TCP/IP, Profibus, ProfiNet, dedicated web server, GSM module for email/SMS transmission on defined events, and a VPN module for secure remote access for troubleshooting and online support – even behind firewalls. This Industry 4.0 capability clearly differentiates LT gas mixers from the competition.

LT gas mixers are designed for minimal maintenance effort. The following tasks are recommended annually:

• Check safety valves for function
• Leak tightness test of the entire system
• Replace filters (usually one per gas inlet)
• Service pressure regulators with maintenance kit
• Calibrate gas analyser with zero and calibration gas
• Inspect pressure vessels in accordance with statutory requirements

A legendary example of robustness: a gas mixer delivered in 1972 (serial number 4) operated reliably for 22 years without any maintenance or readjustment whatsoever – nearly 200,000 operating hours without interruption.

The longevity of LT products is a key advantage:

Typical service life:

• Gas mixer types comfort and smart: Over 25 years
• Dome pressure regulators: Over 30 years
• Gas mixer type advanced: Expected over 15 years

Delivery times:

• Complete gas mixer: 4–8 weeks
• Dome pressure regulators and pressure regulation units and assemblies: Available from stock
• Gas analyser: 4–6 weeks

Availability can be further increased by a redundant system: all components are duplicated, so the second system takes over immediately in the event of a failure.

LT gas mixers are manufactured and tested in accordance with comprehensive European and national standards. Typical conformity and approval documentation includes:

• CE Declaration of Conformity
• ATEX Declaration of Conformity (required for flammable gases in the EU)
• Pressure Equipment Directive (PED) – Declaration of Conformity and TÜV Module G
• EMC and Low Voltage Directive
• Design and manufacture according to ISO 9001:2015
• DIN EN ISO 12100:2011-03 Safety of machinery
• DIN EN ISO 13577, Industrial thermoprocessing equipment – in particular safety requirements for the generation and use of protective and reactive gases
• DIN EN ISO 13849-1:2023-12 Safety-related parts of control systems
• DIN ISO/TR 14121-2:2013-02 Risk assessment

Documentation includes leak tightness tests, pressure tests, gas analyser test certificates, calibration certificates, P&ID, circuit diagrams and operating instructions. LT GASETECHNIK is also certified to ISO 9001 and ISO 45001.

Yes, LT GASETECHNIK offers a free gas mixture calculator with which the gas quantities for static gas mixers of types smart and comfort can be calculated and set. The calculator determines the correct setting values for the metering valves based on the desired gas composition and operating parameters. You simply read off the calculated values on the variable area flow meters and set them precisely.

This function is a key advantage over proportional valve mixers, where the user is dependent on the factory setting of the manufacturer. With LT gas mixers, the actual flowing gas quantities are displayed at all times and can be set reproducibly. The optional gas analyser additionally verifies and monitors the mixed gas quality during operation.

LT GASETECHNIK has over 50 years of experience in the safety engineering of systems for flammable gases and in handling hydrogen.

Specifically, the safety concept includes: hydrogen-compatible fittings and elastomers, explosion protection concepts for the mechanical area, integrated gas warning and interlocking systems, and a pressure-tight double safety function via dome pressure regulator and outlet valve. In the event of carrier gas failure, all gas lines are automatically isolated.

Depending on the concept, LT recommends for H₂ installations a gas warning system integration that automatically shuts down in the event of a leak. On customer request, the gas mixing system can undergo a systematic hazard assessment (HAZOP) and be equipped with SIL-classified safety components in accordance with EN IEC 61508.

The gas mixer type comfort is designed to 25 barg – a decisive advantage over the smart type with a maximum of 10 barg. This higher pressure rating offers several practical benefits: the stainless steel buffer vessel is rated for 25 bar, and cold-tough metallic materials are used as standard.

In addition, the 25 barg design enables a larger operating range for the outlet pressure (up to 22 barg), which can be critical in applications with higher network pressures.

Dome pressure regulators are significantly superior to spring-loaded pressure regulators in terms of control and accuracy. LT GASETECHNIK manufactures exclusively dome pressure regulators and differentiates itself from the competition through the particularly large dome chamber, which achieves superior control accuracy.

A further advantage: pressure regulation units and pressure regulation assemblies are custom-built at LT for the respective gas type and gas pressure. The two leading industrial gas producers rely on LT products and include them in their standard central gas supply catalogues.

The enduring quality of the LTD-1 is impressively demonstrated: a 35-year-old dome pressure regulator sent in for servicing continues to perform reliably after the installation of a maintenance kit.

The dome pressure regulators from LT GASETECHNIK offer five key advantages:

1. No hunting: Even with large inlet pressure fluctuations, the particularly large dome chamber with its compressible gas pressure accumulator ensures smooth, stable control
2. Wide performance range: 1 to 2,500 Nm³/h
3. Large working pressure range: Adapted pressure ranges for low, medium and high pressure
4. Short delivery times: Standard models available from stock
5. Complete solutions: Assembled and tested ex works – with bypass, pressure gauge, pilot regulator, shut-off and safety valve in individual configuration
   

The proven LTD-1 dome pressure regulator is available in various standard configurations:

• Pressure display: Pressure gauge for inlet pressure and/or outlet pressure
• With pilot pressure regulator: Built-in, reversible, spring-loaded pilot regulator, supplied with inlet pressure – for simple adjustment via handwheel with readout on the pressure gauge
• Pilot chamber with outlet pressure: Pilot chamber charged with outlet pressure for maximum stability in back-pressure and automatic compensation of temperature-related pressure fluctuations

Available connection sizes are 1″, 2″ and 3″ in brass or stainless steel. For high-pressure applications, the LTD-1 HD variant is available for up to 400 bar. All configurations are custom-built for the respective gas type and gas pressure and can be ordered as part of complete solutions – assembled and tested ex works.

Delivery time depends on the complexity of the project. Standard gas mixers from the smart, comfort and advanced series are deliverable within 4 to 8 weeks. Dome pressure regulators, dome pressure regulation units and assemblies are often available from stock or at short notice. Customer-specific gas mixing systems require longer lead times due to the engineering effort involved, which are agreed on a project-specific basis. For current delivery times, we recommend a direct enquiry: mail@lt-gasetechnik.com

LT GASETECHNIK offers comprehensive after-sales service: on-site or remote commissioning, training for operating staff, maintenance kits for annual in-house maintenance, calibration service for gas analysers, telephone support and remote diagnostics via VPN. An on-site optimisation service is also available for gas mixers and gas mixing systems. LT supports systems throughout their entire service life – even after 15 or 35 years.

LT gas mixers and gas mixing systems are used in numerous industries. Key customers include the industrial gas industry (Linde, Air Liquide, Praxair), the glass industry (Pilkington, Saint-Gobain), metal processing (ThyssenKrupp, Aurubis), the electronics industry (Siemens, ABB), the automotive industry (Mercedes, VW, Porsche, BMW), the chemical industry (BASF, Evonik) and research institutes. In total, LT GASETECHNIK has realised over 2,000 gas mixer reference installations in more than 35 countries worldwide.

LT gas mixing systems are used for a wide variety of industrial gas mixtures. The most common combinations include:

• H₂/N₂ (forming gas) – for the metal and glass industries
• C₃H₈/air (SNG) – as a natural gas substitute
• CO₂/Ar – welding gas for the automotive industry
• N₂/air (lean air) – for the synthetic resin and chemical industries
• SO₂/N₂ and Cl₂/Ar – for special applications
• Natural gas/H₂ – for hydrogen enrichment for test institutes and the energy transition

In addition, LT manufactures gas mixing systems for various C-gases to produce natural gas substitutes for test institutes. In general: whether neutral, flammable, corrosive or aggressive gases – LT GASETECHNIK has a proven solution for almost every gas type.

Availability can be increased by various measures. The most important option is a redundant system: all components are duplicated, and the second system takes over automatically if the first fails. Should the gas supply to both gas mixers fail, LT GASETECHNIK recommends a bundle supply with pre-mixed gas as a final fallback.

A bypass line provides additional safety: it engages purely mechanically or automatically if the mixer fails or the gas analysis reports a deviation – typically, pre-mixed gas (bundle supply) or neutral gas (e.g. nitrogen) is then provided via a bypass system.

LT GASETECHNIK was founded in 1971 and has continued to develop steadily since then. The company currently employs just under 40 staff and achieves an annual turnover of between 2 and 5 million euros with healthy average annual growth. For over 50 years, LT GASETECHNIK has been one of the world’s leading manufacturers of gas technology solutions, with more than 2,000 installed reference systems in over 35 countries.

The company combines extensive know-how in the areas of gas applications, process engineering, electrical engineering and manufacturing. Many employees have many years of experience in the technical gas industry and bring in-depth knowledge of gas and thermal processes. This broad range of expertise enables LT GASETECHNIK to develop tailor-made solutions for complex gas technology requirements – from consulting through engineering to manufacturing and commissioning.

LT GASETECHNIK is a manufacturer of technical gas systems for gas pressure regulation, gas conditioning and gas mixing in the performance range of 0.1 to 10,000 Nm³/h. All systems are delivered turnkey – custom-built in cabinets, open steel frames or containers, depending on technical requirements and local conditions.

The product range includes:

• Gas mixers for protective gas, forming gas, welding gas and fuel gas supply (standard: 15 to 500 Nm³/h)
• Gas mixing systems for SNG production and natural gas substitution
• Dome pressure regulators (LTD-1, LTD-2, LTD-3) and pressure regulation stations
• Safety fittings for autogenous engineering and industrial gases
• Gas analysis with IoT options

All systems are manufactured in Germany in accordance with ISO 9001:2015 and the Pressure Equipment Directive, and delivered with TÜV approval, ATEX conformity and SIL-compliant gas analysis as required.

LT GASETECHNIK stands for “beyond standards” – solutions that go above and beyond the standard, tailor-made, individual and fit for purpose. This is reflected in concrete advantages:

• Experience with process-engineering-demanding solutions at extreme temperatures, pressures and with corrosive gases
• Industry 4.0: Remote access, connection to process control systems, gas mixers with their own homepage
• Durable quality: Products in service for over 30 years – LT continues to support systems even after 15 years

The total cost of ownership (TCO) speaks in favour of LT: robust design, simple maintenance and long service life make LT products economically superior.

“LT GASETECHNIK” stands for “L+T GASETECHNIK Klöpper-Waldmann GmbH & Co. KG”, which is why many also know the company as “L + T” (spoken “L and T”). Today we abbreviate this to LT, LTG or LT GASETECHNIK. Not to be confused with LNT Gasetechnik, a former market participant that is no longer active.

The company was originally named after its founders in 1971: Ludewig + Tillmann Gasetechnik, which was later shortened to L+T. Both founders had previously held management positions at Witt Gasetechnik and brought their gas technology expertise to the new company.

Current information, news and practical examples can be found on our blog. We regularly publish articles on technical topics such as gas mixers, pressure regulation technology and the energy transition. On LinkedIn, you can follow the LT GASETECHNIK company profile to stay informed about current projects and industry news.

LT GASETECHNIK has realised more than 2,000 gas mixer reference installations in over 35 countries worldwide, from standard solutions to highly complex, customer-specific gas mixing systems. In addition, 250 customer-specific gas mixing systems have been delivered, approximately 90 of which include hydrogen blending.

Regular customers include well-known industrial gas companies such as Linde (framework contract supplier since 2015), Air Liquide, Praxair/Nippon and Air Products. Further customers come from the automotive industry (Mercedes, VW, Porsche, BMW), the glass industry (Pilkington, Saint-Gobain), the steel industry (ThyssenKrupp, Aurubis), electronics (Siemens, ABB) and chemicals (BASF, Evonik). Research institutes such as the Gas and Heat Institute Essen or TU Munich also rely on LT technology.