Vacuum pumps are used to evacuate and dehydrate the sealed unit.
They can be low and high vacuum. Low vacuum pumps are those that cannot produce a vacuum greater than 685.8 mm Hg or 27 ”. Therefore, theoretically, a low vacuum pump will reach a maximum of 685.8mm Hg or 27 ”vacuum.
High vacuum pumps are those that produce a vacuum above 736 mm Hg or 29 ”. These pumps reach a maximum vacuum of 760mm Hg or 29.92 ”.
