11. Still, at very high altitudes, the extremely large engine bells tend to expand the exhaust gases down to near vacuum pressures. 12. However, if there was a drop in the vacuum pressure level it would be an indication that there was an air leakage. 13. All materials, solid or liquid, have a small vapour pressure, and their outgassing becomes important when the vacuum pressure falls below this vapour pressure. 14. Moderate vacuum pressure readings can be ambiguous without the proper context, as they may represent absolute pressure or gauge pressure without a negative sign. 15. To their dismay, CDC investigators discovered condensation in many of the glass tubes, indicating that the rubber stoppers had decayed and vacuum pressure had been lost. 16. If the applied vacuum pressure is too great it can cause bursting of blood vessels, bruising, blistering, damage to erectile tissue, and other types of trauma. 17. Therefore there could only have been 14.2 psi of " vacuum pressure " even if the other end of the pipe were connected to perfect vacuum. 18. The most common method for air separation is vacuum pressure swing adsorption ( VPSA ), are commercially used to separate a single component from ordinary air. 19. "' Blast gates "'are used to focus a dust collection system's vacuum pressure for maximum dust ( or other material ) extraction at the desired location. 20. Its main side effects are minor and infrequent, mainly a reddish pinpoint rash on the penile surface and bruising if the vacuum pressure is maintained for too long.