Discharge Assembly

Hong Kong sewer rising mains typically discharge via an embedded 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. 

Traditional designs use Ductile Iron fittings (see Fig.1 below), the problem is the life span is short, 10-15 years before replacement or significant maintenance is required due to the H2SO(Sulphuric acid) which 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 hydrophilic sealing rings to ensure no leakage of sewer from the chamber around the fitting.

The assembly is factory fabricated to order from PE100+ standard fittings available on our website (Elbows, Bell-mouth & Puddle Flange). A PE assembly has a 100-year operating life, 6x longer than equivalent DI fittings.

 

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, Z1 & le given in the table below as the shortest possible lengths that can be fabricated. Longer lengths are available at time of order to suit the client's chamber design and wall thickness.

Dimension 'le' should be outside of the chamber wall to provide sufficient length to connect the puddle to the pipe using an electrofusion coupler.

Larger sizes up to 2000 OD are available, Contact us for design drawings.
AoR Dimensions are Available on Request
When designing the discharge chamber, dimensions L4, Z, Z1 & le can be manufactured any length, but not less than the dimensions given in the table above.
Pipe Size Bellmouth OD Puddle thickness Puddle  OD Taper Long Spigot Min. Dimension Min. 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