Home | Siphonic Roof Drainage | Gravity to HydroMax® Siphonic Comparison

Gravity To Siphonic Roof Comparison

  • Horizontal pipes need pitch slope. The water flow-rate is dictated by the gradient available(this gradient also restricts the distance a pipe can travel as you use up available ceiling space).
  • This leads to Multiple rainwater pipes in locations largely dictated by the sloping horizontal pipes rather than design team choice.
  • Gravity drains/pipes require ⅔ air to transport ⅓ water = big diameters.
  • Vortex formation at the gravity roof drain results in the water being transported in an inefficient spiral motion rather than straight into the pipe below.
  • Limited or No testing data to produce flow ponding graphs for Gravity Drains = unidentified ponding on roof

“With Gravity, Life’s a Pitch!”

HydroMax® = Design Flexibility – Find Solutions not possible using Gravity

  • Smaller Diameter pipe work – approximately half the gravity diameter following same routing
  • Less downpipes = Reduction in Below Grade Drainage
  • Rainwater downpipes routed to the design team/client’s chosen locations freeing up valuable building space.
  • Routing of rainwater pipes to the outside walls – Eliminates Below Grade Drainage Under the Building Floor.
  • Pipes run full-bore with self-cleaning properties.
  • Easy coordination of services due to pipework running flat.
  • Less pipes = Reduced construction time and cost.
  • Ability to route rainwater pipes to pond retention or Rainwater Harvesting. And LEED benefits.
  • Less Ponding on the roof due to suction effect
  • BIM modeling compatibility
  • Eliminate Vertical Downpipes
  • Eliminate Internal Downpipes
  • Eliminate Drainage Under Building Floor
  • Less pipework
  • Smaller diameters (pipes, fittings, couplings, insulation, hangers)
  • Less labor
  • Quicker to install and obtain a watertight building

SAVING 32% of Pipework and Labor with Smaller Diameters
Virtually eliminating below grade drainage with its extensive trenching.

Traditional Gravity Solution

530 metres Pipework
Diameters 160mm to 450mm
11 Manholes

HydroMax® Siphonic Scheme

Only 360 metres Pipework
Diameters 56mm to 200mm
1 Manhole

Gravity v HydroMax® in High Rise – Eliminate Vertical Downpipes

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