Innovative inverted siphon flush for continuous cleaning of underpass pipes

The Challenge 

Sew­er net­works are gen­er­al­ly oper­at­ed by grav­i­ty and are laid to the local topo­graph­i­cal con­di­tions. Deep sew­ers are expen­sive, pump­ing sta­tions are expen­sive and not always desir­able, so when obstruc­tions such as water­cours­es, roads or rail­ways are encoun­tered solu­tions such as invert­ed siphons are often employed. All invert­ed siphons require reg­u­lar main­te­nance as they are prone to sed­i­men­ta­tion due to low veloc­i­ties.  

Up to now, invert­ed siphons have been cleaned with clear­ing blades, flush­ing and force pumps from an up-stream posi­tion. Flush­ing from the siphon head is of lim­it­ed suc­cess as the flush takes place in the water cush­ion of the invert­ed siphon where the force is dispelled.

The Way (patented)

Water is non-com­press­ible and for this rea­son, it is bet­ter to install flush­ing devices down­stream which draws the water instead of com­press­ing. When the Hydro­Guard^® shield is low­ered into the sew­er, this stops the flow from con­tin­u­ing down­stream and at the same time, impounds the flow with­in the invert­ed siphon and the upstream sew­er net­work. This impound­ing stores the required flush­ing vol­ume and rais­es the hydraulic head across the siphon sec­tion. When the Hydro­Guard^® shield opens, the stored water cre­ates a pow­er­ful, almost tur­bu­lent, high veloc­i­ty flush. The water lev­el quick­ly drops upstream and air is drawn into the invert­ed siphon. The water becomes com­press­ible and its increased mobil­i­ty pro­vides the pres­sure shocks (water ham­mer) required for the improved clean­ing result (see illustration).

The Product (patented)

The Hydro­Guard^® Invert­ed Siphon Flush is installed down­stream of the invert­ed siphon at a con­ve­nient man­hole. It con­sists of a flush­ing shield, an elec­tro-hydraulic dri­ve, water lev­el sen­sors upstream and down­stream as well as on-site con­trols with option­al remote controls.

Areas of Application

• under­pass­ing waters 
• under­pass­ing traf­fic routes
• under­pass­ing buildings

The Advantages

• robust stain­less-steel construction
• retro­fit, also through small openings
• space-sav­ing 
• hydraulic dri­ve
• auto­mat­ic operation
• con­tin­u­ous flushing
• high oper­a­tional safety
• large hydraulic flow
• high flow velocity
• high shear stress
• high degree of cleaning
• no read­just­ment
• design sup­port from Steinhardt