Wood preservation is the act of treating and impregnating wood by stabilizing dimensions, increasing strength and resistance to water moisture and chemicals and reducing cracking; primarily completed with autoclave under vacuum.
The structure of wood is similar to a sponge, with cell cavities and cell walls, which represent the actual wood. The aim of wood preservation is to coat these walls with preservative to protect from decay caused by wood-destroying fungi and insects. The preservative penetrates deep into the wood with the aid of pressure and vacuum. First, the vacuum removes the air from the cavities to create space for the preservation solution. This solution is forced deep into the wood under high pressure.
One of many possible arrangements for wood preservation
Basic Wood Preservation Process Procedures
Wood preservation is a common practice in to resist wood rotting and infestation due to earth or water, fungi, insects and other elements. This process is widely employed in damp and excessively humid areas. Therefore, to obtain maximum penetration of preservatives, vacuum is used to impregnate the wood.
While process requirements vary widely both in desired vacuum and capacity, the basic procedures are similar. These procedures consist of initial vacuum, filling, application of pressure, discharging the solution, recovery vacuum and end of 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 more effective, the following stages of treatment. The length of the vacuum cycle will vary with the type of wood.
Filling - 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. Time required will vary widely with the size and type of lumber, the solution pressure and the efficacy of 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 introduction to 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.
Learn More About NASH Products For Wood Treating Vacuum Applications
NASH liquid ring vacuum pumps offer several advantages to the wood treating industrial application. Liquid ring vacuum pumps have no trouble handling the saturated air with entrained liquid and are very tolerant of the resinous components and vapors from the preservative chemicals.
NASH liquid ring vacuum pumps offer the following features and benefits while working in wood preservation 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 less downtime
•No metal – to – metal contact – simple operation and wear-free performance
•Cool running – incoming vapor is condensed. Smaller, less costly equipment can 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
NASH Liquid Ring Vacuum Pumps Deliver Advantages To Wood Treating Industrial Applications - Learn More About How It Works In This Animation From Gardner Denver Nash
Economical Vacuum Pump Solutions
Vectra, VectraPak and SC liquid ring vacuum pumps are the wood treating industry’s preferred solution. These systems deliver innovative solutions to harsh industrial environments while exceeding customer-specific requirements.
NASH Vectra liquid ring vacuum pumps are designed for 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 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 excel in applications, such as wood treating that require high vacuum. Vectra vacuum pumps meet high combustible range standards and are ATEX certified. NASH Vectra vacuum pumps are designed for harsh environments and 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.
Furthermore, NASH VectraPaks are standardized pre-engineered solutions containing necessary components that are assembled and piped. Customers purchase NASH VectraPaks because they arrive ready to install, available in iron and stainless steel with quick delivery.
The NASH SC liquid ring vacuum pump is perhaps the most popular pump that delivers reliable performance with a broad range of suction volume, vacuum and pressure. The SC series is a single stage liquid ring vacuum pump available in 9 different models with capacity ranging from 130 to 3,200 ACFM (220 to 5,440 m3/hr).
Global Provider of Liquid Ring Vacuum Pumps
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.
Download The Brochure To Learn More About Our Standard Package Solutions For Wood Preservation
NASH is part of Gardner Denver, Inc., a leading global manufacturer of highly engineered products. Gardner Denver is headquartered in Milwaukee, Wisconsin, USA and has facilities in more than 30 countries.