Slopes for forced sewage pipe
Slopes for forced sewage pipe
(OP)
Hello,
I need a help and advise, please!
5 independent source of saniraty sewage will pump the sewage through pressurized piping to collecting tank.
Can we lay the pressurized piping with no slope?
Also what other procedures can we apply to prevent clogging (is flushing with water practical thing to do?), because at the worst case scanario, when we have one pump operated, the speed of the flow will reach only 0.3m/sec.
regards,
strelok
I need a help and advise, please!
5 independent source of saniraty sewage will pump the sewage through pressurized piping to collecting tank.
Can we lay the pressurized piping with no slope?
Also what other procedures can we apply to prevent clogging (is flushing with water practical thing to do?), because at the worst case scanario, when we have one pump operated, the speed of the flow will reach only 0.3m/sec.
regards,
strelok





RE: Slopes for forced sewage pipe
RE: Slopes for forced sewage pipe
yes, each of the source will have a pit, from which they will pump to the system. The main pressurized sewage collector is 12". each source of sewage will be connected to the main pressurized collector through 6" line.
Hydraulics calculation shows that when we have all sources under operation we can reach 0.6m/s flow velocity. But when we have only one pump under operation, the velocity is around 0.16m/sec which I believe is very low. Because the system is temporary and will exist only couple of years, we would like to introduce some procedures to prevent clogging, but I don't know which? Flushing with water seems a way to go? I need an advise!!!!
RE: Slopes for forced sewage pipe
KRS Services
www.krs-services.com
RE: Slopes for forced sewage pipe
I agree with KRS that you need someone that routinely handles pressure systems to look at it. Especially if you have concerns.
RE: Slopes for forced sewage pipe
I will try to look at other options. thank all of you for help.
RE: Slopes for forced sewage pipe
You cannot "purchase" some gravity pipe, add a few pumps and expect to live happily ever after, so to speak. I have had the pleasure of putting in several pressure systems, similar to the needs you wrote about, and each had unique considerations for design. You stated that the pipe was purchased with the intent to use as a gravity system, but then discovered that sloping the pipe was not possible. Your boss could have saved his money and hired guys like me who do this for a living. We could have then recommended a few options, but now, your options are very limited without significant expense.
Gravity pipe is really not meant for presures, and if you are not careful, someone is going to get hurt or killed (if for example the pipe is overhead and not properly supported and it fails due to pressure) because the original problem has not been properly thought out.
KRS Services
www.krs-services.com
RE: Slopes for forced sewage pipe
I recently completed start-up of a lift station only to find that the force main to which we connected is lacking a number of air/vac combo valves. The FM runs generally downhill, so I expected sections of the line to be empty (drained by gravity) between pump cycles. Instead what I've found is static head in the line that is as much as 85 feet above what would be expected based on the high point in the line. Here's my questions: Does anyone know that composition of the gasses generated in a sewer line? I know the general constituents, but not the real percentages of each. At what pressure is "normal" sewer gas forced back into solution? If one end of the force main is open to atmosphere, how can the static pressure in the line be 85 feet higher than the highest point of any element in the system? Why do the gas bubbles not expand to atmospheric equilibrium when all pumps are off? Any help or insight would be appreciated.
RE: Slopes for forced sewage pipe
When you start pumping, the water probably completely fills the pipe at some point down the hill, trapping an air bubble above it. That bubble will (if the water velocity is not high enough to expell it) already be at or work its way to the high point in the pipe. There it will restrict the available flow area of the pipe. The smaller flow area will cause the point of operation to move left along the pump curve and create higher system pressures with lower flows.
In order to eliminate it, you will probably need to install air-release valves, especially at the high points.