Confirm that exhaust air hole from vacuum chamber is venting into a fumehole, because hazardous fumes will be discharged from vacuum chamber. Place sample into the vacuum chamber and return the lid, making sure it is well seated. Turn switch, labelled main, on and observe that an indicator light has illuminated. Turn pump to on position. Watch gauge on the vacuum chamber and be sure that needle does not pass 90 kilopascals or 27 inches of mercury.
Implosion can result.
When gauge begins to approach 90 kilpascals or 27 inches of mercury, turn pump off. The vacuum will remain, but decrease with time. Observe sample to see air bubbles being released. After 30 to 45 seconds begin to release vacuum with release valve. When releasing pressure, be sure to do so slowly.