Vacuum Pressure Impregnation for Wood Treatment

Tolerant, Reliable Vacuum Solutions

NASH liquid ring vacuum pumps, compressors & systems offer several advantages to wood treatment applications. They have no trouble handling the saturated air with entrained liquid. They are also very tolerant of the resinous components and vapors of preservative chemicals. Review our product portfolio below to learn more!

About Wood Preserving

Wood preservation impregnates the wood to stabilize its dimensions, increase its resistance to water and chemicals, and reduce cracking.

The structure of wood is similar to a sponge, with cell cavities and cell walls, which represent the actual wood. Wood treatment coats these walls with preservatives to protect them from decay caused by wood-destroying fungi and insects. 

The preservative penetrates deep into the wood with pressure and vacuum. The vacuum removes the air from the cavities to create space for the preservation solution. The solution is then forced deep into the wood under high pressure.

Basic Process

Basic Process of Vacuum Pressure Impregnation for Wood Treatment
One of the many possible arrangements for wood preservation.


Wood treatment resists wood rotting and infestation due to soil or water, fungi, insects, and other elements. This process is widely employed in damp and excessively humid areas. To obtain maximum penetration of preservatives, vacuum is used to impregnate the wood.

While process requirements vary in the desired vacuum and capacity, the basic procedures are similar, consisting of initial vacuum, filling, application of pressure, discharging the solution, recovery vacuum, and end of a cycle.

  • Initial Vacuum - Once the wood is sealed in the autoclave, vacuum is applied using a single stage NASH vacuum pump. This removes some surface moisture and expands cell structure for easier penetration. Removal of air at this point accelerates, and makes the following stages of treatment more effective. The length of the vacuum cycle varies with the type of wood. 
  • Filling - The preservative is introduced from a storage tank, initially by vacuum, and finally by a multistage high-pressure solution transfer pump. 
  • Application of Pressure – Autoclave pressure is raised between 100 and 200 psig and held until desired penetration is achieved. The time required varies with the size and type of lumber, the solution pressure, and the efficacy of the preconditioning. 
  • Discharging the Solution – Any solution not absorbed by the wood is returned to the storage tank for reuse. In some cases, solution removal may be assisted by using compressed air.
  • Recovery Vacuum – Another round of vacuum is used to help the bonding of the active principles of wood. 
  • End of Cycle – The autoclave returns to atmospheric pressure and the wood is removed.

Nash Drives Real World Cost Savings for Global Material & Chemical Production Company

When a leading, global material & chemical production company sought to upgrade its legacy equipment, they chose to continue their long-standing relationship with Nash.


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Vacuum Pressure Impregnation

Features & Benefits

NASH liquid ring vacuum pumps offer the following features and benefits for wood treatment applications:

  • Ability to handle, process carryover or recycled gases - increases operating efficiency and reduces operating costs
  • Long design life – highest reliability
  • No internal lubrication required -  less maintenance and downtime
  • No metal – to – metal contact – simple operation and wear-free performance
  • Cool running – incoming vapor is condensed and smaller, less costly equipment to service application
  • Only one moving part – simple and trouble-free operation
  • Proven energy-efficient design – lower operating costs
  • Over a century of engineering and application experience – peace of mind

Watch This Animation from Nash to Learn How Our Liquid Ring Vacuum Pumps Work In Wood Treatment Applications


Economical Solutions

Vectra XL

NASH Vectra XL, VectraPak, and SC liquid ring vacuum pumps are the wood preservation industry’s preferred systems that deliver innovative solutions to harsh industrial environments while exceeding customer-specific requirements.

Our Vectra XL liquid ring vacuum pumps are designed for the rigorous, nonstop demands of harsh industrial environments. These systems are held to the highest standard of reliability and manufactured to achieve optimum performance and unprecedented production efficiencies. Vectra XL liquid ring vacuum pumps are a revolutionary line of economical pumps that are of great value to customers.

NASH Vectra single stage liquid ring vacuum pumps provide a high vacuum, meet high combustible range standards, and are ATEX certified. Our vacuum pumps are available in ductile iron and stainless steel and accommodate a variety of mechanical seals.

Fundamental elements of the Vectra XL vacuum pump design includes improved cone angles, which decreases the size of the pump and NASH patented Gas Scavenging Technology, which improves pump performance at high vacuum levels.


Learn More About Our Vectra XL

NASH Vectra XL for Vacuum Pressure Impregnation
NASH Vectra XL vacuum pump for vacuum pressure impregnation wood applications.


NASH SC is the most popular pump that delivers reliable performance with a broad range of suction volume, vacuum, and pressure. The SL series is a single-stage liquid ring vacuum pump available in 12 different models with a capacity ranging from 140 to 9,700 ACFM (240 to 16,500 m3/hr).


Learn More About Our SC Vacuum Pumps

NASH SC vacuum pumps for vacuum  pressure impregnation for wood treatment
NASH SC vacuum pump for vacuum pressure impregnation for wood applications.
NASH Vectrapak for Vacuum Pressure Impregnation for Wood Applications
NASH VectraPak systems for Vacuum Pressure Impregnation for Wood Treatment Applications.

VectraPak Vacuum System

Furthermore, VectraPaks are standardized pre-engineered solutions containing the necessary components that are assembled and piped. Customers purchase these because they arrive quickly and are ready to install.


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Global Provider

NASH is a leading global provider of liquid ring vacuum pumps. For over 110 years, Nash has been providing reliable, engineered systems that stand up to the rigorous, nonstop demands of harsh industrial environments.

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