Backdrop Bends
Backdrop Chamber Bend
Typically referred to as a Backdrop Bends, this single piece assembly is fabricated to order. Backdrop bends are offered in the required DSD drawing fitting radius (r = ≥4 x DN). The drop pipe material is M90ES SDR 17 CCTV PE 100 RC pipe, there are no joints, steps or internal weld beads in the drop or bend portion, offering an exceptionally smooth internal surface. r = 4 x DN, so the fitting meets the requirements of the following DSD drawing:
DS1020D Backdrop Manhole Type 3
Unlike Cast Iron, PE does not corrode so the interior surface of the PE remains smooth over the life of the fitting. Therefore the use of tighter radii bends at the bottom of the drop are possible, with limited risk of blockage. The use of alternatives bend radii may be necessary where a r => 4 x DN bend is simply too large to install in the available space.
Mill-Pro PE Backdrop bends are supplied with a factory welded integrated puddle flange in accordance with DSD Appendix 5A Clause 5.10.3.2
When PE is cast into concrete there is no adhesion between PE and cement. Due to thermal expansion of the PE during concrete curing, a small gap is created between the PE and the cured concrete after cooling. A Hydrophilic seal is fitted where the PE exits the concrete at the manhole base, this seal expands up to 600% when wet to permanently seal the PE and concrete chamber walls. This seal is designed in accordance with DSD Appendix 5A, Clause 5.10.3.3
Approval to use Backdrop bends with r = 1xDN or 2.5 D should be sort from the engineer
Fabricated PE100 / RC / Backdrop Manhole Bend / SDR17 / Radius = ≥ 4x DN
DSD Compliant, dimensions Z1 & Z2 are stated in the tables as greater the or equal to (≥), they can be fabricated longer than the stated value below to suit site requirements, but not less than. It is recommended that dimension Z1 is ordered longer than required and cut to length on site before plastering the entrance
| Product code | DN | dn | Z1 | Z2 | r | Availability in Hong Kong |
| P5314.563.160 | 150 | 160 | ≥ 760 | ≥ 920 | 720 | 8-12 Weeks |
| P5314.563.225 | 200 | 225 | ≥ 1068 | ≥ 1243 | 1013 | 8-12 Weeks |
| P5314.563.250 | 225 | 250 | ≥ 1185 | ≥ 1365 | 1125 | 8-12 Weeks |
| P5314.562.280 | 250 | 280 | ≥ 1190 | ≥ 1381 | 1120 | 8-12 Weeks |
| P5314.562.355 | 300 | 355 | ≥ 1510 | ≥ 1735 | 1420 | 8-12 Weeks |
| P5314.562.400 | 350/375 | 400 | ≥ 1695 | ≥ 1940 | 1600 | 8-12 Weeks |
| P5314.562.450 | 400 | 450 | ≥ 1895 | ≥ 2160 | 1800 | 8-12 Weeks |
| P5314.562.500 | 450 | 500 | ≥ 2095 | ≥ 2375 | 2000 | 8-12 Weeks |
Fabricated PE100 / RC / Backdrop Manhole Bend / SDR17 / Radius r = 2.5 x DN
Dimensions Z1 & Z2 are stated in the tables as greater the or equal to (≥), they can be fabricated longer than the stated value below to suit site requirements, but not less than. It is recommended that dimension Z1 is ordered longer than required and cut to length on site before plastering the entrance
| Product code | DN | dn | Z1 | Z2 | r | Availability in Hong Kong |
| P5314.561.160 | 150 | 160 | ≥ 440 | ≥ 600 | 400 | 8-12 Weeks |
| P5314.561.225 | 200 | 225 | ≥ 618 | ≥ 793 | 563 | 8-12 Weeks |
| P5314.561.250 | 225 | 250 | ≥ 685 | ≥ 865 | 625 | 8-12 Weeks |
| P5314.561.280 | 250 | 280 | ≥ 770 | ≥ 961 | 700 | 8-12 Weeks |
| P5314.561.355 | 300 | 355 | ≥ 978 | ≥ 1203 | 888 | 8-12 Weeks |
| P5314.561.400 | 350/375 | 400 | ≥ 1095 | ≥ 1340 | 1000 | 8-12 Weeks |
| P5314.561.450 | 400 | 450 | ≥ 1220 | ≥ 1485 | 1125 | 8-12 Weeks |
| P5314.561.500 | 450 | 500 | ≥ 1345 | ≥ 1625 | 1250 | 8-12 Weeks |
| P5314.561.560 | 500 | 560 | ≥ 1400 | ≥ 1400 | 1400 | 8-12 Weeks |
| P5314.561.630 | 525 | 630 | ≥ 1575 | ≥ 1575 | 1575 | 8-12 Weeks |
Fabricated PE100 / RC / Backdrop Manhole Bend / SDR17 / Radius r = ~ 0.5x DN
Dimensions Z1 & Z2 are stated in the tables as greater the or equal to (≥), they can be fabricated longer than the stated value below to suit site requirements, but not less than. It is recommended that dimension Z1 is ordered longer than required and cut to length on site before plastering the entrance
| Product code | DN | dn | Z1 | Z2 | r | Availability in Hong Kong |
| P5314.560.160 | 150 | 160 | ≥ 116 | ≥ 276 | 76 | 8-12 Weeks |
| P5314.560.225 | 200 | 225 | ≥ 162 | ≥ 337 | 107 | 8-12 Weeks |
| P5314.560.250 | 225 | 250 | ≥ 179 | ≥ 359 | 119 | 8-12 Weeks |
| P5314.560.280 | 250 | 280 | ≥ 203 | ≥ 394 | 133 | 8-12 Weeks |
| P5314.560.355 | 300 | 355 | ≥ 259 | ≥ 484 | 169 | 8-12 Weeks |
| P5314.560.400 | 350/375 | 400 | ≥ 285 | ≥ 530 | 190 | 8-12 Weeks |
| P5314.560.450 | 400 | 450 | ≥ 309 | ≥ 574 | 214 | 8-12 Weeks |
| P5314.560.500 | 450 | 500 | ≥ 333 | ≥ 613 | 238 | 8-12 Weeks |
