Discharge Assembly

Hong Kong sewer rising mains typically discharge via a 90º bend and Bellmouth into the discharge chamber at the end of the pipeline. This design of discharge assembly helps to minimise air intake into the line when pumping ceases. 

Typical designs use Ductile Iron (see Fig.1 below), the problem with Ductile Iron is the life span is short, 15 years before replacement or significant maintenance is required. In a discharge chamber, the raw sewer is constantly exposed to air as pumping starts and stops. Sewer and air create H2SO(Sulphuric acid), this rapidly attacks Ductile Iron and concrete surfaces (See Fig.2 below). 

Mill-Pro fabricates a typical DSD sewer rising main discharge assembly in Polyethylene.  This includes an integrated puddle flange to anchor the end of the pipeline into the chamber against both pressure and thermal forces. The puddle flange includes a hydrophilic sealing ring to ensure no leakage of sewer from the chamber around the fitting and a Bellmouth for discharge.

The assembly is factory fabricated to order from PE100+ standard fittings available on our website (Elbows, Bellmouth & Puddle Flange) once installed this assembly has a 100-year lifespan, 5-6x longer than the equivalent DI products.

 

Polyethylene Discharge Assemblies / PE100+ / PN10-PN16 / SDR17-11

Factory fabricated from PE100+ standard fittings, manufactured to order base don client dimensions, supplied complete with a hydrophilic sealing ring to ensure water tightness once cast in place.

Dimensions L4, Z and Z1 given in the table below as the shortest possible lengths that can be fabricated, lengths longer than this are available at time of order to suit the client's chamber design and wall thickness.

Pipe Size Bellmouth OD Puddle thickness Puddle  OD Taper Long Spigot Minimum Dimension Minimum Dimension Height
dn D W D4 L3 le L4 Z Z1
110 146 20 AoR AoR 150 ≥233 ≥503 ≥171
160 213 20 AoR AoR 150 ≥267 ≥537 ≥238
200 266 20 AoR AoR 150 ≥293 ≥563 ≥292
225 299 20 AoR AoR 150 ≥310 ≥580 ≥323
250 332 20 AoR AoR 250 ≥326 ≥696 ≥355
280 373 21 AoR AoR 250 ≥346 ≥717 ≥402
355 473 27 AoR AoR 300 ≥389 ≥824 ≥497
400 532 30 AoR AoR 300 ≥411 ≥861 ≥546
450 599 34 AoR AoR 300 ≥435 ≥905 ≥521
500 666 37 AoR AoR 300 ≥461 ≥946 ≥565
560 746 42 AoR AoR 300 ≥488 ≥998 ≥619
630 839 47 AoR AoR 300 ≥522 ≥1057 ≥681

Note:

1. Larger sizes up to 2000 OD are available on request

2. AoR Dimensions are Available on Request

3. When designing the discharge chamber, dimensions L4, Z & Z1 must be equal to or greater than the dimensions given in the table above.