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Liquid Ring Vacuum Pump 
Large Capacity, 904

Capacity 3,000 to 13,000 ACFM (5,000 to 22,000 m³/h)

The NASH 904 replaced the popular NASH CL pump in the 1980's, and can still be found operating in plants around the globe today. Capacities of the 904 pumps range upward from about 3,000 ACFM at vacuum. These durable pumps can handle excess liquid carryover without any difficulty, even if it arrives as massive slugs. 904 pumps are found in many industries including paper, chemical, and mining.


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Efficient and Reliable with Proven Performance

The 905 liquid ring vacuum pump and compressor series is an upgrade to the proven 904 model and has been engineered to deliver improved performance and reliability. 

The 905 provides lower life-cycle costs with an improved variable port design, enabling a wider operating range with improved efficiency, water saving technology, and simpler seal line piping. It also includes a patented gas scavenging feature to provide superior performance and longevity at high vacuum levels. 


Designed to operate in demanding environments

The 905 series has been engineered for reliable operation and performance in harsh applications such as chemical processing, paper, mining, geothermal power generation or anywhere reliable compression of corrosive gases is needed. Constructed of 316L stainless steel the 905 offers excellent corrosion resistance and can be outfitted with a variety of mechanical seals. 

Operates as a vacuum pump and compressor with a discharge pressure range of 36 psia (2.5 bar abs.)

Some applications require vacuum and compression in one process. Instead of handling the gas with two separate machines, our liquid ring vacuum pump and compressor models can do the job with only one pump - reducing cost and simplifying installation. 

Conical Porting and Rotor Configuration

Patented in 1932, Nash’s variable conical porting design allows the force of compression to counter the weight of the rotor and shaft to help minimize load on bearings during operation. The variable porting optimizes pump performance across the entire operating range. With constant innovation, Nash’s patented design features:

  • Option for lobe purge to minimize damage from erosion in duties with solids present

  • Large differential pressure capability

  • Gas scavenging feature minimizes slip of gas from discharge to inlet improving capacity, especially at deep vacuum

  • High liquid carryover tolerance

  • Side discharge to minimize chance of flooded start

  • Self-priming design may allow elimination of booster pump in recirculated systems


Factory Service

Strategically located to provide support where and when you need it.



Built to our legendary standards using current designs and specifications. Fit and performance guaranteed.

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Field Service

Our team of NASH Certified Technicians are available to supplement your in-house maintenance operations.

Technical Data

Liquid Ring Vacuum Pump Large Capacity 9
  • Suction Capacity: 3,000 to 13,000 ACFM (5,000 to 22,000 m3/h)

  • Vacuum Range: to 3.5 inHgA (to 120 mbar abs.)

  • Discharge Pressure Range: 36 psia (2.5 bar abs.)

  • Differential Pressure: to 22 psi (to 1.5 bar)

  • Shaft Seals: Stuffing Box (standard), Mechanical Seals (single acting/ double acting) on request

  • Materials of Construction: 316L Stainless Steel

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