Beschrijving
ZW-6/7 Nitrogen Compressor – Precision Oil-Free N2 Booster for Medium-Pressure Process Applications
Delivering 6 m³/min at 0.70 MPa discharge pressure, the ZW-6/7 is a two-stage, two-row oil-free piston nitrogen compressor engineered for precision process control, small-scale VPSA nitrogen boosting, and medium-pressure industrial gas distribution. Zero lubricant contamination, compact footprint, and optimized for reliable continuous-duty operation.
Productoverzicht
The ZW-6/7 nitrogen compressor is a precision-engineered member of our oil-free piston compressor family, purpose-built for applications demanding both compact dimensions and elevated discharge pressure. With a rated capacity of 6 m³/min and a discharge pressure of 0.70 MPa, this unit occupies a unique niche between small laboratory compressors and large industrial boosters, serving process industries that require medium-pressure nitrogen in moderate flow quantities.
Unlike conventional lubricated compressors that necessitate elaborate downstream purification trains, the ZW-6/7 operates on a fully oil-free compression principle. Its PTFE composite piston rings and rider bands function without hydrocarbon lubricants, ensuring the nitrogen product stream maintains ISO 8573-1 Class 0 oil content certification. This inherent purity is indispensable for pharmaceutical process inerting, electronics soldering atmosphere control, and precision chemical synthesis where even trace oil contamination can compromise product integrity.
The two-stage, two-row (二列二级) architecture divides the compression workload across paired cylinders, with an inter-stage cooler maintaining gas temperatures within safe thermal envelopes. Despite its modest 6 m³/min capacity, the ZW-6/7 achieves a 0.70 MPa discharge pressure through optimized thermodynamic staging—delivering the pressure performance of larger units within a footprint of just 720 × 763 × 1475 mm and a weight of 0.80 tonnes.
Technical Specifications – ZW-6/7
| Parameter | Value | Unit |
|---|---|---|
| Model | ZW-6/7 | – |
| Patroon | Two-stage, Two-row (二列二级) | – |
| Capaciteit | 6 | m³/min |
| Afvoerdruk | 0.70 | MPa |
| Compressor Size (L × W × H) | 720 × 763 × 1475 | mm |
| Gewicht | 0.80 | t |
| Stroom | 45 | kW |
| Spanning | 380 | V |
| Gasmedium | Nitrogen (N₂) | – |
| Lubrication | Olievrij | – |
* All specifications are rated at standard reference conditions (ISO 1217, Annex C). Actual performance may vary based on site altitude, ambient temperature, and inlet conditions.
Key Features & Engineering Advantages
1. Ultra-Compact Vertical Design
The ZW-6/7 achieves exceptional space efficiency through a vertically oriented crankcase that minimizes longitudinal footprint while preserving full maintenance access. At 720 × 763 × 1475 mm, the unit occupies less than 0.55 m² of floor area—comparable to a standard office desk. This dimensional economy makes the ZW-6/7 ideal for installations in crowded utility rooms, containerized systems, mobile nitrogen supply trailers, and retrofit applications where existing machinery rooms lack space for larger equipment. The 0.80-tonne weight permits positioning by standard pallet jack or manual hydraulic lift, eliminating the need for overhead cranes or forklift equipment.
2. Advanced Oil-Free PTFE Sealing System
The ZW-6/7 employs a self-lubricating piston ring and rider band assembly manufactured from high-density PTFE composites reinforced with glass fiber and bronze micro-particles. This material matrix achieves a dynamic coefficient of friction below 0.08 without any hydrocarbon lubricant, delivering ISO 8573-1 Class 0 oil content certification directly at the compressor discharge. For process industries where nitrogen purity is non-negotiable—such as pharmaceutical sterile manufacturing, electronics wafer fabrication, and food-grade packaging—this native oil-free performance eliminates the capital expense, energy penalty, and maintenance burden of downstream coalescing filters, activated carbon adsorbers, and oil monitoring instrumentation.
3. Two-Stage Thermodynamic Optimization for 0.70 MPa
The two-stage, two-row compression architecture is specifically optimized for the 0.70 MPa discharge pressure target. The first-stage cylinder compresses nitrogen from suction pressure to an intermediate pressure, after which a shell-and-tube intercooler reduces the gas temperature before second-stage compression to final discharge pressure. This staged approach limits the pressure ratio per cylinder to approximately 2.6:1, maintaining discharge temperatures below 145°C and preventing thermal degradation of the PTFE sealing elements. The two-row opposed-cylinder arrangement provides inherent first-order force balance, reducing vibration transmission to the foundation by over 80% compared to single-row designs of equivalent capacity.
4. Efficient 45 kW 380V Direct Drive
The ZW-6/7 is driven by a 45 kW, 380V, 50Hz three-phase induction motor conforming to IEC 60034-1 IE3 premium efficiency standards. The standard 380V configuration integrates directly into conventional industrial electrical panels without requiring medium-voltage infrastructure, specialized switchgear, or step-down transformers. This electrical simplicity is particularly advantageous for small and medium enterprises upgrading from bottled nitrogen or membrane generators to on-site compression, as it minimizes electrical installation costs and commissioning complexity. The motor is direct-coupled to the crankshaft via a flexible disc coupling, eliminating belt maintenance and alignment issues.
Application Scenarios
Small-Scale VPSA Nitrogen Booster Stations
For compact VPSA nitrogen generators producing 500–1,500 Nm³/h of 99.5–99.9% purity nitrogen at near-atmospheric pressure, the ZW-6/7 serves as the ideal booster companion. Its 6 m³/min capacity aligns with the output of small to medium VPSA units, while the 0.70 MPa discharge pressure provides sufficient head for distribution to multiple point-of-use stations within a facility. The ZW-6/7 nitrogen booster can be skid-mounted alongside the VPSA generator, creating a fully integrated on-site nitrogen supply system with a combined footprint under 15 m². The oil-free compression path is essential because any hydrocarbon contamination would irreversibly poison the carbon molecular sieve adsorbent, degrading separation efficiency and necessitating costly adsorbent replacement.
Pharmaceutical Process Inerting & Sterile Manufacturing
Pharmaceutical manufacturing facilities require nitrogen for reactor inerting, sterile powder conveying, vial headspace purging, and lyophilization chamber atmosphere control. The ZW-6/7’s 0.70 MPa discharge pressure is well-suited for feeding medium-pressure nitrogen headers serving multiple process skids, while its oil-free certification ensures compliance with FDA 21 CFR 211 (Current Good Manufacturing Practice) and EU GMP Annex 1 (Manufacture of Sterile Medicinal Products). The compact dimensions allow installation within existing pharmaceutical utility corridors without disrupting cleanroom layouts or requiring structural modifications.
Electronics Assembly & Semiconductor Support
In electronics manufacturing, nitrogen is deployed for reflow soldering atmosphere control, wave soldering inerting, dry cabinet storage, and component tape-and-reel packaging. The ZW-6/7’s 6 m³/min capacity can simultaneously supply multiple soldering lines and storage cabinets within a medium-sized electronics assembly facility. The oil-free design is absolutely critical in this sector because even sub-ppm oil contamination can cause solder joint defects, conformal coating delamination, and contamination of optical sensors or camera modules. The 0.70 MPa pressure provides adequate head for nitrogen distribution through standard polyethylene or copper piping networks spanning up to 500 meters.
Precision Chemical Synthesis & Catalyst Protection
Specialty chemical manufacturers and catalyst producers utilize nitrogen for reactor blanketing, catalyst bed preservation, solvent degassing, and product transfer under inert atmosphere. The ZW-6/7’s 0.70 MPa discharge pressure is sufficient for pressurized transfer of sensitive chemicals between process vessels and for maintaining positive pressure in catalyst storage silos. The oil-free compression ensures that no hydrocarbon contaminants are introduced into the process stream, which is particularly important for catalyst manufacturing where trace oil can poison active sites and reduce catalytic efficiency by 15–30%.
Material & Construction
The ZW-6/7 is fabricated from materials meticulously selected for nitrogen compatibility, corrosion resistance, and compact structural integrity:
| Component | Material | Specificatie |
|---|---|---|
| Cylinder Block | Gray Cast Iron | GG25 / HT250, precision-machined bores |
| Crankshaft | Forged Alloy Steel | 42CrMo4, Q&T, ISO 1940 G2.5 balanced |
| Piston Rings | PTFE-Glass-Bronze Composite | Self-lubricating, wear rate <0.04 mm/1000h |
| Rider Bands | PTFE Composite | Piston lateral guidance, anti-scuffing |
| Valve Plates | Roestvrij staal | SS316, concentric ring spring-loaded |
| Intercooler | Carbon Steel Shell / SS304 Tubes | Compact design, 1.5× hydrotest |
| Base Frame | Structural Steel | Welded, vibration-isolated mounting pads |
All pressure-bearing components are designed and manufactured in accordance with ASME BPVC Section VIII Division 1 or Chinese GB 150 standards. Weld joints undergo 100% radiographic inspection (RT), and each pressure vessel is hydrostatically tested at 1.5× MAWP for a minimum 30-minute hold period. The compact intercooler is specifically engineered for the ZW-6/7’s flow rate and pressure ratio, with tube-side velocities optimized for heat transfer efficiency without excessive pressure drop.
Installation & Maintenance Guidelines
Foundation & Spatial Requirements
The ZW-6/7 weighs just 0.80 tonnes and features a remarkably low center of gravity due to its vertical design. A reinforced concrete pad of 1.5–2.0 tonnes is sufficient for stable operation, mounted on elastomeric vibration isolators (natural frequency 10–15 Hz). The two-row opposed-cylinder design inherently cancels first-order inertial forces, minimizing vibration transmission to adjacent sensitive equipment such as analytical balances or optical instruments. Required clearances: 0.6 m on the non-drive side for valve access, 0.5 m on the drive side for motor maintenance, and 1.0 m overhead for lifting the motor or compressor head.
Cooling Water Specifications
Cooling water demand is approximately 8 m³/h at an inlet temperature not exceeding 32°C. The compact intercooler and cylinder jackets share a common cooling water circuit. Acceptable water quality: pH 6.5–8.5, total hardness < 250 mg/L as CaCO₃, chloride < 50 mg/L, suspended solids < 20 mg/L. For installations without municipal water supply, a small closed-loop cooling system with a 0.5 m³ buffer tank and compact air-blast cooler is sufficient.
Preventive Maintenance Schedule
| Interval | Service Item | Action Required |
|---|---|---|
| Daily | Operational Inspection | Check for leaks, abnormal vibration, cooling water flow, discharge temperature |
| 250 hours | Valve Plate Check | Inspect suction/discharge valves for carbon buildup, spring fatigue, or cracking |
| 1,000 hours | Piston Ring Assessment | Measure ring groove clearance; replace if > 0.18 mm |
| 4,000 hours | Intermediate Overhaul | Replace all piston rings, rider bands, and valve plate assemblies |
| 8,000 hours | Major Overhaul | Inspect crankshaft journals, measure bearing clearances, replace as required |
The oil-free architecture of the ZW-6/7 eliminates the entire category of lubricant-related maintenance tasks. There are no oil changes to schedule, no oil analysis laboratory contracts to maintain, no filter elements to stock, and no oil separator cartridges to monitor. The sole recurring consumables are the PTFE piston rings and rider bands, which typically achieve 4,000–6,000 hours of service life under clean nitrogen conditions. For a facility operating 6,000 hours per year, this translates to a single scheduled maintenance event annually.
Compliance & Safety Certifications
The ZW-6/7 nitrogen compressor meets or exceeds the following international standards and regulatory frameworks:
ASME BPVC Section VIII Div.1, GB 150-2011, PED 2014/68/EU Module A
IEC 60034-1 (IE3 efficiency), IEC 60204-1, ISO 12100
ISO 8573-1 Class 0 (Oil Content), TÜV Rheinland independently tested
ISO 9001:2015, ISO 14001:2015
⚠️ Safety Notice
Nitrogen is an odorless, colorless asphyxiant gas that displaces oxygen without warning. All ZW-6/7 installations must incorporate continuous oxygen deficiency monitoring in the compressor room and adjacent corridors. Ventilation systems must be engineered to maintain ambient oxygen concentrations above 19.5% volume per OSHA 29 CFR 1910.146. Alarm interlocks should activate at 19.5% O₂ and trigger automatic compressor isolation at 18.0% O₂. Personnel entry into enclosed compressor rooms requires portable oxygen monitors, two-way communication, and a buddy system. Never enter a nitrogen-enriched atmosphere without self-contained breathing apparatus (SCBA).
Performance & Efficiency Analysis
The ZW-6/7 achieves a specific power consumption of approximately 7.50 kW per m³/min of nitrogen delivered at 0.70 MPa discharge pressure. While this specific power is higher than our larger LW-series models due to the reduced scale efficiency inherent in smaller compressors, it remains competitive within the sub-10 m³/min oil-free piston segment. For comparison, oil-lubricated screw compressors in this capacity range typically consume 8.0–9.0 kW/m³/min, and diaphragm compressors (frequently specified for oil-free applications) can exceed 11 kW/m³/min.
Over a 6,000-hour annual operating schedule, the ZW-6/7’s efficiency advantage versus less efficient alternatives yields approximately 18,000–36,000 kWh of energy savings per year. At $0.08/kWh, this represents $1,440–$2,880 in annual electricity cost reduction. However, the dominant economic justification for ZW-6/7 selection in most applications is the elimination of oil-related consumables and downstream purification infrastructure rather than marginal energy savings.
The total cost of ownership for nitrogen compression in small to medium applications is driven primarily by maintenance labor, consumables, and capital depreciation rather than energy. The ZW-6/7’s oil-free design eliminates oil changes ($300–600/year), filter replacements ($150–300/year), separator cartridge changes ($400–800/year), and oil analysis ($100–200/year), delivering total consumable savings of $950–$1,900 annually compared to lubricated alternatives. Additionally, the absence of downstream oil-removal equipment (coalescing filters, activated carbon adsorbers, oil monitors) eliminates capital costs of $8,000–$15,000 and associated energy penalties of 3–5% of compressor power.
Customization & OEM Capabilities
We offer extensive customization options to adapt the ZW-6/7 to specific installation constraints, process requirements, and end-user preferences:
- Compact Skid Packages: Pre-assembled compressor, motor, intercooler, and control panel on a structural steel skid with forklift pockets. Reduces field installation to electrical connection and cooling water hookup only—typically completed within one working day.
- Mobile Trailer Systems: The ZW-6/7 can be mounted on a road-legal trailer with an integrated diesel generator, closed-loop cooling system, and nitrogen receiver, creating a fully mobile nitrogen supply unit for construction sites, pipeline purging, and emergency response operations.
- Intelligent Control Systems: Optional Siemens LOGO! or S7-1200 PLC with 7-inch HMI touchscreen, Ethernet connectivity, SMS/email alarm notifications, and Modbus TCP/IP compatibility for SCADA integration. Automatic load/unload control optimizes energy consumption during variable demand periods.
- Acoustic Enclosures: Compact IP54-rated sound enclosure reducing noise emission from 80 dB(A) to 65 dB(A) at 1 meter, suitable for indoor installations in noise-sensitive environments such as laboratories, cleanrooms, and office-adjacent utility spaces.
- OEM & Private Label Programs: Custom paint colors, branded nameplates, localized documentation, and region-specific electrical certifications for gas equipment distributors and system integrators.
Custom configurations are available from MOQ 1 unit. Engineering proposals are typically delivered within 3–5 business days. Standard delivery time is 10–12 weeks from order confirmation; expedited delivery within 8 weeks is available for qualifying projects.
Case Study: Pharmaceutical Sterile Manufacturing Nitrogen Upgrade
Client: A sterile injectable pharmaceutical manufacturer in Thailand
Challenge: The facility was utilizing an oil-lubricated nitrogen compressor (5-year-old European brand) for reactor inerting and vial headspace purging. During a routine FDA pre-approval inspection, oil contamination of 1.5 mg/m³ was detected in the nitrogen supply to the aseptic filling line. This finding triggered a warning letter and required immediate corrective action, including a production hold that cost approximately $250,000 in lost batches and delayed product launch.
Solution: We supplied a ZW-6/7 oil-free nitrogen compressor as a direct replacement, mounted on a compact skid with an integrated aftercooler and Siemens LOGO! PLC control panel. The skid was designed to fit within the existing utility room (2.5 m × 1.5 m footprint) without requiring structural modifications. A 0.5 m³ nitrogen receiver was included to dampen pressure fluctuations during rapid valve cycling in the filling line.
Results After 12 Months:
- Nitrogen oil content: Reduced from 1.5 mg/m³ to <0.01 mg/m³, achieving ISO 8573-1 Class 0 and satisfying FDA requirements
- FDA inspection outcome: Zero findings related to nitrogen quality in the subsequent follow-up inspection
- Maintenance burden: Reduced by 60%—elimination of oil changes, filter replacements, and separator overhauls
- Unplanned downtime: Zero events in 12 months of continuous operation
- Production hold risk: Eliminated—no further nitrogen quality-related production interruptions
“The ZW-6/7 compressor solved our compliance crisis overnight. The FDA inspector specifically noted the oil-free certification in his report, and we have had zero nitrogen quality issues since installation. The compact size was a bonus—we didn’t need to expand our utility room.” — Quality Assurance Director, Pharmaceutical Manufacturer
FAQ & Selection Guide
Related Products & Solutions
ZW-8/6 Compact Nitrogen Compressor
Slightly higher capacity (8 m³/min) at 0.60 MPa in the same compact form factor. Ideal for small VPSA booster stations and laboratory nitrogen supply where moderate flow is required.
DW Series High-Pressure Nitrogen Compressors
Medium to high-pressure oil-free compressors (0.40–2.00 MPa) for nitrogen injection, pipeline boosting, and chemical synthesis. Capacities from 2 to 130 m³/min.
LW Series Large-Capacity Nitrogen Compressors
High-flow oil-free piston compressors (20–130 m³/min) for cryogenic ASU backup, VPSA boosting, and industrial pipeline distribution. Discharge pressures from 0.30 to 0.80 MPa.
For a complete overview of our industrial nitrogen compressor portfolio, including oil-free oxygen compressors, hydrogen compressors, carbon dioxide compressors, and custom-engineered specialty gas solutions, please contact our application engineering team or browse our online product catalog.
Ready to Upgrade Your Nitrogen Compression System?
Our application engineers are available to evaluate your nitrogen flow requirements, inlet conditions, discharge pressure targets, and integration constraints. We provide complimentary technical proposals, layout drawings, piping and instrumentation diagrams (P&IDs), and detailed total cost of ownership (TCO) analyses within 48 hours of receiving your inquiry.
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