Vacuum Pump Stations
Inches of mercury (in Hg) is a unit of measure of pressure or in this case, negative pressure.
30 in Hg vacuum = -1 atmosphere = -14 p.s.i. = -34 ft. H2O
That's like trying to suck your chocolate milk out of a straw
34 feet long, straight up. That concludes our science lesson for today.
Where were we? Oh yeah, so the vacuum lines are under this negative pressure,
which is constantly changing due to the vacuum valves operating, allowing
us to collect the sewage into the collection tank in the lower level of the
We now need to move the sewage from here towards the Treatment Plant. We use centrifugal pumps in our vacuum pump stations to remove the sewage from the collection tank and pump it through a force main to another location.
This is either directly to a gravity pump station wet well or to a gravity sewer line where it then flows to a gravity pump station.