Double-diaphragm and packed plunger pumps with full motion mechanisms


Capable of superior performance in even the most severe operating conditions, the Nexa Series packed-plunger and hydraulic double-diaphragm metering pumps represent one of heavy industry’s most versatile, robust and reliable fluid metering and dosing solutions.

Nexa’s exceptional build quality enables stable dosing even under extreme operating pressures and temperatures, from wellhead chemical injection in oil and gas applications to pyrophoric liquids handling in chemical compounds manufacturing.

Designed to meet API 675 3rd edition standard and compliant to Norsok M-501 & M-630, NACE 0175, ATEX2014/34/EU, TR CU 004-010-020-012/2011 and Shell DEP (various), Nexa can be safely operated in hazardous processes, reassuring operators of the pump’s suitability regardless of the application.

Technical Features

Pressureup to 600 barg for hydraulic diaphragm and 650 for packed plunger
Flow Rateup to 10,000 l/h with a single head
Fluid temperature from -20°C to 80°C (from -40°C to 150°C on request)
Wetter PartsSS 316L, PP, PVDF and PTFE (exotic alloys available on request)


Full-motion type in seven different sizes, featuring:
  • Oil-bath lubrication
  • Low-noise internal worm gearbox
  • High-precision stroke adjustment for ultrafine volume control
  • Increased turndown ratio achievable via frequency converter
  • Housing available in cast iron as standard and nodular cast iron to cope with harsh ambient conditions
  • Exakta-designed electrical and pneumatic actuators available

Nexa Mechanism

Technical information

Mechanism available in seven different sizes to ensure maximum reliability and best performances.

N0, N1 Mechanisms


Stroke Length [mm]

Plunger Diameter Range [mm]

Thrust [kN]

Hydraulic Power [kW]



4 - 50





6 - 90



N2, N3 Mechanisms


Stroke Length [mm]

Plunger Diameter Range [mm]

Thrust [kN]

Hydraulic Power [kW]



10 - 120





15 - 130



N4, N5 Mechanisms


Stroke Length [mm]

Plunger Diameter Range [mm]

Thrust [kN]

Hydraulic Power [kW]



30 - 130





35 - 140



N6 Mechanism


Stroke Length [mm]

Plunger Diameter Range [mm]

Thrust [kN]

Hydraulic Power [kW]



35 - 145




Exakta is committed to developing flexible and customized valve configurations with flow channels specifically designed to improve hydraulic efficiency while coping with different conditions and applications.

SEAM Cone Valve

Thanks to additive manufacturing technology, delivers high performance with SS 3D printing while allowing endless shape possibilities to meet unique in-valve fluid dynamics for every application.


  • Lower NPSH required (up to 10%)
  • Increased volumetric efficiency (3%)
  • 30% lighter than conventional machined valves
  • Enhanced durability for longer mean time between repair

VEEP Cone Valve

Engineered to cater to diverse fluid demands, VEEP Cone Valve offers outstanding performance while ensuring self-cleaning functionality. Its unique operating direction prevents fluid obstruction to the valve’s seals and guide, enhancing its reliability.

VEEP Cone Valve’s design incorporates a component of engineered polymer compound that provides excellent protection against abrasive fluid particles, ensuring compatibility with particulate and abrasive fluids.


  • Lower NPSH required (up to 10%)
  • Compatibility with particulate fluids
  • Compatibility with abrasive fluids

Advantages at a glance

The superior versatility of Nexa pump drive unit allows motors to be mounted left-sided, right-sided or even vertically depending on the installation requirements.

Nexa also allows different-sized mechanisms to be coupled, with casings designed to maintain the same foot level in order to allow installation on a flat support base.

An internal gearbox allows pumps with different stroke adjustment to be combined to form multihead units for greater flexibility.
With Exakta's tailor-made manufacturing approach, customers can personalize their Nexa series pump with multiple drive units combination, hydraulic configurations, piping connections, suction and discharge solutions and accessories to withstand temperature extremes, aggressive chemicals and difficult suction conditions encountered in challenging applications.
All Nexa mechanisms, regardless of size, can be easily combined to form larger metering units with significant construction advantages, simplifying assembly and installation.

Mechanisms are coupled together using joints with no exposed parts, resulting in a compact unit with a strong and perfectly-aligned connection which removes the need for a special base.

As process demands for changes in process conditions, users can quickly and easily add a pump to an existing system by performing a few simple coupling operations, even on site.

Industry Applications

Oil & Gas
  • Wax inhibitors, pour point depressants, asphaltene inhibitors, scale inhibitors injection to prevent equipment blockage
  • Corrosion inhibitors, oxygen scavenger, biocides, demulsifiers, foam inhibitors metering to extend the lifetime of pipelines and process equipment
  • Dosing of antifoams, de-oilers, demulsifiers, nitrate inhibitors, sodium hypochlorite to eliminate the water-bearing formations of crude oil and natural gas
  • Methanol, MEG/TEG injection to remove control the hydrates formation to prevent clogging and choking in flow lines
  • Drag-reducing agents and polymers metering to reduce the downhole pressure loss during the fluid pumping
  • Oleochemicals
  • Fatty acid production and processing for cosmetics, lotions and softeners production
  • Conversion of fatty acid to biodiesel
  • Glycerine processing for concentrated flavour extracts, texture improver and emulsifiers
  • Plastics
  • Antioxidants for plastic processing where weathering resistance is needed
  • Colourants for coloured plastic parts
  • Foaming agents for expanded polystyrene and polyurethane
  • Lubricants injection to avoid plastic sticking to the mould
  • Antimicrobials injection to provide a biocide treatment to control germs or fungi
  • Chemical & Petrochemical
  • Caustic soda, organic sulphur injection to reduce refinery column-overhead hydrochloric acid corrosion
    Sour water for stripper column
  • Organic chloride, dimethyl disulfide, ammonia, antifoam, odorizing agents, for crude oil separation and conversion for further use
  • Wash water and condensate disposal and transfer
  • Pyrophoric liquids for chemicals production
  • Fertilizers
  • Metering of nitric acid and ammonia for the production of nitrogenous fertilizers
  • Injection of sulphuric acid for the production of phosphorous fertilizer
  • Urea production
    Multi-compound fertilizers production
  • Power Generation
  • Phosphate dosing to prevent scale formation in boiler tubes
  • Oxygen scavenger to prevent corrosion
  • Amine dosing to neutralize the carbonic acid present in the condensate
  • pH control through ammonia injection
  • Biocide for bacteria prevention in boilers tubes
  • Industrial Effluent Treatment
  • Removal of solid particles
  • Adjustment of pH levels
  • Odour control
  • Disinfection
  • Sludge treatment and removal
  • Alkaline water electrolysis for
  • hydrogen production
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