ChemVak WH-8D Dual-Stage Rotary Vane Vacuum Pump

Overview

The ChemVak WH-8D is a dual-stage, oil-sealed rotary vane vacuum pump engineered for reliable and stable operation across demanding laboratory and pilot-scale industrial vacuum applications. Based on the proven Couette-flow principle of positive displacement, the WH-8D utilizes two counter-rotating vanes within an eccentrically mounted rotor to progressively compress gas from the inlet to the exhaust, achieving high compression ratios and deep ultimate vacuum levels. Its dual-stage architecture enables continuous evacuation down to 4×10⁻⁴ mbar — significantly deeper than single-stage alternatives — making it suitable not only as a standalone roughing pump but also as a high-performance backing pump for high-vacuum systems such as diffusion pumps, turbomolecular pumps, and cryopumps. Designed and manufactured in the USA, the WH-8D integrates precision-machined cast aluminum housing, hardened steel vanes, and proprietary oil formulation compatibility to ensure long-term dimensional stability and minimal wear under sustained duty cycles.

Key Features

• Dual-stage rotary vane design delivering consistent ultimate vacuum of ≤4×10⁻⁴ mbar and nominal pumping speed of 135 L/min at 50 Hz
• IP54-rated sealed motor with integrated thermal overload protection for safe, uninterrupted operation in variable ambient conditions
• Gas ballast (air bleed) valve enabling controlled admission of atmospheric air to prevent condensable vapor lock during water vapor or solvent-rich evacuation
• Low-noise operation (<54 dB[A]) achieved via balanced rotor dynamics, vibration-damping mounting, and optimized oil mist separation
• Front-access circular oil sight window with calibrated scale for rapid, accurate oil level verification without tools or disassembly
• Oil-return prevention mechanism minimizes backstreaming upon shutdown, eliminating post-cycle oil spitting and protecting downstream vacuum chambers
• DN25 KF flange inlet port compliant with ISO-KF standards, ensuring seamless integration with common vacuum tubing, valves, and gauges
• Reduced oil mist emission via multi-stage coalescing baffles and labyrinth seals — supporting cleaner lab environments and reduced maintenance frequency

Sample Compatibility & Compliance

The WH-8D is compatible with a broad range of non-corrosive and mildly aggressive vapors commonly encountered in analytical, pharmaceutical, and materials science workflows — including water, ethanol, acetone, ethyl acetate, and low-concentration organic acid vapors. Its construction materials (anodized aluminum housing, nitrile elastomer seals, stainless steel shaft) provide enhanced resistance to chemical degradation compared to entry-level vane pumps. The pump meets UL/CSA electrical safety standards and conforms to IEC 61000-6-3 (EMC emissions) and IEC 61000-6-2 (immunity). While not intrinsically rated for Class I Div 1 hazardous locations, its sealed motor and absence of internal sparking elements support use in general-purpose laboratories operating under GLP-compliant quality systems. Documentation packages include factory calibration records traceable to NIST standards and RoHS-compliant material declarations.

Software & Data Management

As a standalone mechanical vacuum source, the WH-8D operates without embedded firmware or digital control interfaces. It is fully compatible with third-party vacuum system controllers (e.g., Pfeiffer Vacuum DUO, Edwards nXDS, or Agilent Vacuubrand systems) via analog 0–10 V or 4–20 mA process signals when equipped with optional pressure transducer feedback loops. For audit-ready environments governed by FDA 21 CFR Part 11 or EU Annex 11, external data loggers can record operational parameters — including runtime hours, motor current draw, and inlet pressure trends — using standard Modbus RTU or Ethernet/IP protocols. Maintenance logs, oil change intervals, and performance validation checks (per ASTM F2629-21 for vacuum pump verification) are supported through ChemVak’s downloadable LabLog™ template suite.

Applications

• Roughing and backing for high-vacuum systems in surface science (XPS, AES), thin-film deposition (sputtering, evaporation), and electron microscopy
• Vacuum distillation and fractional crystallization in synthetic organic chemistry and natural product isolation
• Lyophilization (freeze-drying) of biologics, vaccines, and diagnostic reagents under controlled primary drying conditions
• Vacuum-assisted filtration for membrane integrity testing, particulate analysis, and sterile filtration validation
• Leak detection via helium mass spectrometry (where WH-8D serves as foreline pump for the MS detector)
• Vacuum packaging of moisture-sensitive reference standards and calibration materials in metrology labs
• Evacuation of gloveboxes and inert-atmosphere reactors prior to purging with nitrogen or argon

FAQ

What is the recommended oil change interval for the WH-8D under continuous operation?
Under typical laboratory usage (≤8 hrs/day, ambient temperature <35°C), oil should be replaced every 500 operating hours or semiannually — whichever occurs first. Extended exposure to water vapor or solvents may require more frequent changes; oil condition can be verified using ASTM D92 flash point testing or FTIR spectroscopy.
Can the WH-8D be used with aggressive halogenated solvents like chloroform or carbon tetrachloride?
No. Halogenated hydrocarbons degrade nitrile seals and accelerate vane corrosion. For such applications, ChemVak recommends the WH-F series fluorocarbon-elastomer-equipped pumps or dry scroll alternatives.
Is the gas ballast valve intended for continuous operation?
The gas ballast is designed for intermittent use during initial pump-down of condensable-laden loads. Continuous operation with gas ballast open reduces ultimate vacuum performance and increases oil oxidation rate.
Does the WH-8D comply with ISO 8573-1 Class 0 for oil-free air?
No — as an oil-sealed pump, it is not classified as oil-free. However, when paired with a high-efficiency oil mist filter (e.g., ChemVak OM-200), exhaust air meets ISO 8573-1 Class 3:2:2 for particulate, water, and oil aerosol content.
What is the maximum allowable inlet pressure for safe operation?
The WH-8D must not be operated above 100 kPa(a) (atmospheric pressure) at the inlet. Sustained operation above 10 kPa(a) without gas ballast may cause oil emulsification and reduced ultimate vacuum.