| Application | Laser cutting, food packaging, electronics, metal heat treatment, pharmaceutical packaging, or oil and gas | Application-specific | Identify whether nitrogen is used for blanketing, purging, oxidation prevention, cutting, packaging, or process control. | Choose the generator technology and purity level according to the process risk, not only the highest available purity. |
| Nitrogen Demand | Average and peak nitrogen consumption | Approximately 5–5,000 Nm³/h for on-site industrial systems | Calculate the total consumption of all connected equipment, including simultaneous operation, start-up demand, and future expansion. | Size the generator for the peak demand and consider a reserve capacity of approximately 10–20% where continuous production is required. |
| Required Nitrogen Purity | Purity expressed as nitrogen concentration | 95% to 99.999% N₂, depending on the process | Confirm the maximum acceptable oxygen concentration and whether residual moisture, oil, or hydrocarbon limits apply. | Higher purity generally requires additional separation capacity, more energy, or lower product flow at the same equipment size. |
| Low-Purity Nitrogen | Blanketing, pneumatic conveying, fire prevention, and some metal applications | 95–98% N₂ | Suitable when moderate oxygen reduction is sufficient and the process does not require oxygen-sensitive protection. | Membrane systems can be economical for stable, moderate-purity requirements and continuous operation. |
| Medium-Purity Nitrogen | Food packaging, tank blanketing, laser cutting, and general industrial purging | 98–99.9% N₂ | Verify the required oxygen concentration at the point of use rather than relying only on the generator outlet specification. | PSA systems are commonly selected because they provide flexible flow and purity adjustment. |
| High-Purity Nitrogen | Electronics, pharmaceutical processes, laboratory use, and sensitive heat treatment | 99.99–99.999% N₂ | Define oxygen, moisture, and hydrocarbon limits separately because nitrogen purity alone may not describe gas quality. | Use high-purity PSA or membrane polishing, with suitable filtration, drying, monitoring, and storage equipment. |
| Required Flow Rate | Continuous nitrogen production capacity | 5–5,000 Nm³/h, depending on system size | Specify flow in Nm³/h or Sm³/h and state the reference temperature and pressure used for the gas measurement. | Compare suppliers using the same reference conditions; actual volumetric flow changes with temperature and pressure. |
| Peak Flow and Intermittent Demand | Short-duration demand above the average consumption | Typically 1.2–2.0 times the average demand for intermittent processes | Record the duration and frequency of peak events, such as vessel purging, laser piercing, or packaging line start-up. | Use a nitrogen buffer tank for short peaks when a larger generator would otherwise be needed. |
| Operating Pressure | Nitrogen pressure required at the point of use | Commonly 4–10 barg; some systems require up to approximately 40 barg with compression | Separate generator outlet pressure, storage pressure, distribution pressure, and final equipment inlet pressure. | Select a generator and compressor combination that meets the required pressure after allowing for filters, piping, valves, and pressure losses. |
| Feed-Air Pressure | Compressed air pressure supplied to the generator | Commonly 7–10 barg for PSA systems; membrane systems may use similar or higher pressure | Check the minimum pressure available during compressor unloading, peak plant demand, and seasonal operating changes. | Insufficient feed-air pressure can reduce nitrogen flow, purity, or both. |
| Recommended Generator Technology | Membrane, PSA, or cryogenic separation | Membrane: generally lower-to-medium purity; PSA: flexible medium-to-high purity; cryogenic: very large flow and very high purity | Compare required purity, flow, pressure, operating hours, footprint, and expansion plans. | For most small and medium on-site industrial applications, membrane or PSA technology is typically more practical than cryogenic production. |
| Product Dew Point | Moisture content of the nitrogen gas | Commonly −40°C atmospheric-pressure dew point for industrial systems; lower values may be specified | State whether the dew point is measured at atmospheric pressure or operating pressure. | Use an air dryer and suitable downstream filtration when the application is sensitive to moisture. |
| Compressed-Air Quality | Oil, liquid water, particles, and hydrocarbons in feed air | Clean, dry, filtered compressed air is required | Review compressor type, air-treatment equipment, filter ratings, drain arrangements, and maintenance records. | Poor feed-air quality can damage separation media, increase operating costs, and cause unstable product purity. |
| Operating Schedule | Daily operating hours and annual duty cycle | Intermittent, single-shift, multi-shift, or 24/7 operation | Estimate annual running hours and identify whether production must continue during maintenance. | For continuous operation, consider automatic switching, duty/standby equipment, remote alarms, and critical spare parts. |
| Buffer Storage | High-pressure nitrogen receiver or buffer tank | Often sized for short-term peak demand and pressure stabilization | Base the tank volume on peak flow, required hold-up time, pressure range, and allowable pressure fluctuation. | A correctly sized receiver can reduce generator cycling and improve supply stability. |
| Energy Consumption | Electricity used by compressors, dryers, controls, and auxiliary equipment | System-specific; commonly evaluated in kWh per Nm³ of nitrogen | Request power consumption at the specified purity, flow rate, feed pressure, and operating condition. | Do not compare power figures unless the purity, flow reference, inlet conditions, and product pressure are identical. |
| Instrumentation and Control | Monitoring of purity, pressure, flow, dew point, and alarms | Basic local control to PLC-based remote monitoring | Define required sensors, data logging, alarm contacts, communication protocol, and automatic shutdown functions. | Online oxygen analysis is recommended when nitrogen purity is a critical process parameter. |
| Safety and Compliance | Pressure equipment, oxygen-deficiency risk, ventilation, and electrical safety | Must comply with the applicable local regulations and site standards | Review pressure-vessel documentation, relief valves, ventilation, oxygen-deficiency monitoring, and electrical requirements. | Nitrogen is non-flammable but can displace oxygen; enclosed areas require appropriate ventilation and safety controls. |
| Supplier Documentation | Technical proposal and performance guarantee | Performance data at defined test conditions | Request P&ID, datasheets, utility requirements, purity-flow curves, noise data, manuals, certificates, and recommended spares. | Require the supplier to state guaranteed purity and flow at the exact operating pressure and feed-air conditions. |
| Example Selection | Food packaging line with moderate continuous demand | 50 Nm³/h at 99.5% N₂ and 6 barg delivery pressure | Add peak-flow data, required dew point, operating hours, and available compressed-air pressure. | A PSA or membrane system may be suitable; final selection should be based on the verified purity-flow curve and total operating cost. |