A Pressure Treat

Welcome to All Sensors “Put the Pressure on Us” blog. This blog brings out pressure sensor aspects in a variety of applications inspired by headlines, consumer and industry requirements, market research, government activities, and you.

A Pressure Treat

Pressure treating wood stabilizes its dimensions, protects it from insects, increases its resistance to water and chemicals and reduces cracking. The pressure treating process involves both vacuum and pressure. Initially, a vacuum removes the air from the cavities in the wood to create space for the preservation solution. The vacuum levels in a given process vary but could range from -700 mmHg to -730 mmHg.

Then, a protective solution, commonly alkaline copper quat or ACQ, is forced deep into the wood under high pressure in an autoclave.  A hydraulic overpressure of 12 atmospheres or somewhere between 100 and 200 psig is common.

In general, the basic procedure consisting of initial vacuum, filling, application of pressure, discharging the solution, recovery vacuum and return to atmospheric pressure at the end of a cycle.

In the United States, the chemical protection from applying high pressure (in psi) is measured in the pounds of chemical per cubic foot (PCF) increase in the density of the wood. The density ranges from 0.40 PCF for ground contact to 0.60 PCF for foundations.

Pressure Treated WoodA basic pressure treating process uses pressure and vacuum.
Source: Nash by Gardener Denver.

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