EPAMS technical features

Last updated on Wed, 10/03/2012 - 10:02

EPAMS syphonic roof drainage systems design recommendations

An EPAMS pipework consists of one or several horizontal pipes without fall connected to a dowpipe: horizontal runs and stacks are made of ENSIGN- SMU S cast iron components.

The joints are made with SMU Rapid 2 or any other coupling able to withstand a negative pressure of 900 mbar.

Connections of the roof outlets to the pipe system:

Depending on the jobsite constraints, the connection can be made flat or vertical. 

Decompression zone:

Before connecting to the sewer main syphonic systems have to run by gravity again.

EPAMS design recommends:

At the end of the downpipe, the bottom pipe increases in diameter –generally two extra diameters – causing decompression and reducing the flow velocity.

Case n°1:
Vertical decompression zone in the last metre of the stack.

Case n°2:
Decompression zone directly connected to a manhole.

Case n°3:
Horizontal decompression zone

Pipe support

Stack support pipes are installed at the bottom of stacks to address forces due to changes in the streamflow regimes.
Every 15 metres, is the general requirement.

Pipe brackets

Because of high discharge rates, rubber lined steel brackets are compulsory.

Specific points of the network:

Gripped couplings

On EPAMS pipeworks, grips collars are specified on couplings where they shall withstand dislocation forces.

Horizontal pipe connected to the outlet when expected pressure is over 0.5 bar or -0.5 bar.

The negative pressure will be at the highest at the head of the stack (down to - 0.9 bar); the couplings will be there systematically installed with grip collars.

Change of direction: in changes of direction on stacks and low collectors, the couplings will be gripped. Where a change of direction will be added or removed, SAINT-GOBAIN PAM will carry out a new study taking the new head loss into account.

The decompression zone is subject to high turbulences, and subsequently, every component at the bottom of the stack, before the return to gravity flow regime, shall be gripped.

All the gripped components are specified in the isometries of the design study.

Reduction of flow sections

Seeking balance of potential energy and head losses on the pipework can call for reduction of the nominal diameters to increase head losses.
By regulation, the reduction of nominal diameter (DN) of discharge pipes is prohibited in the direction of flow, except for siphonic systems like EPAMS (EN 12056-3 §7.6.5) Where it can be useful to control the pressure level.

Increase and reduction of nominal diameters are made with the tapered pipe reducer.

On horizontal runs, the pipe reducer will be installed so that the pipe invert is continuous.