Condron Concrete Works produce a complete range of manhole components, all of which are certified to I.S. 420: 1989 and I.S. 420: 2004 in conjunction with ISEN 1917 and supersedes I.S. 420: 1989 in October 2004
Advantages of Precast Manholes:
The main advantages of precast concrete manhole units over in situ concrete construction are:
- Units are factory produced to I.S. 420: 1989, I.S. 420: 2004 and I.S. EN 1917
- They are manufactured in wide range of sizes and depths.
- They are simple to assemble requiring relatively unskilled labour on site.
- Units are capable of being constructed as flexible watertight structures.
- They are supplied fitted with steps to EN 13101: 2002 Class C
- The structure is durable with its own inherent strength.
- Base Units:
- Chamber/Inspection Units:
- Cover Slabs:
- Quality Control and Testing
- Typical Manhole Construction
The diameter of our Manhole Base is 1200mm and as can be seen from Table 11, an extensive range of channel sizes and floor plans are available which would cater for the vast majority of site requirements. The all socketed units are designed so that a seal can be provided on all connections, with double spigoted sections available for connecting the outlet to the socket of the first downstream pipe. The 150mm, 225mm and 300mm channel sizes are also available with sockets and gaskets suitable for use with plastic pipes. Heights and Weights of Manhole Bases are as shown on the tables below.
Heights and weights of Chamber Rings
|Internal Diameter of Chamber Rings||Wall Thickness (Approx.)||Height (Approx Weight in kgs)||Height (Approx Weight in kgs)||Height (Approx Weight in kgs)||Height (Approx Weight in kgs)|
|Internal Diameter of Chamber Rings||Wall Thickness (Approx.)||1.00m||0.75m||0.50m||0.25m|
2 number 32mm diameter lifting pin for 900,1050,1200mm Manhole Chamber units/Base units
3 number 45mm diameter lifting pins for 1350,1500,1800mm Manhole Chamber units.
3 number 50mm diameter lifting pins for 2100,2400mm Manhole Chamber units.
Heights and weights of Manhole Bases
|Channel Size||Overall height (Approx.)||Effective Height (Invert to top of Base)||Approx Weight in kgs for Base Types||Approx Weight in kgs for Base Types||Approx Weight in kgs for Base Types||Approx Weight in kgs for Base Types|
|Channel Size||Overall height (Approx.)||Effective Height (Invert to top of Base)||Type 1||Type 2||Type 3||Type 4|
AVAILABLE MANHOLE BASE PLANS IN 1200MM Ø BASES
|150mm Diameter Channel|
|225mm Diameter Channel|
|300mm Diameter Channel|
|375mm Diameter Channel|
Manhole Base with 300mm ø channel (Type 1) showing correct position of Butyl Sealant
All chamber sections are fitted during manufacture with 350mm wide plastic coated aluminium rung steps, which are spaced 250mm apart, thereby providing a uniform step interval in all units.
The black polyethylene covering on the steps is resistant to nearly all media and also prevents sparking when walked on with iron-mounted boots. The steps comply to EN 13101: 2002 Class C
Chamber Rings can be supplied reinforced if required. All sections are jointed using our CS 202 Butyl Sealant giving an immediate and flexible watertight joint.
Heights of chamber sections are as shown on the table.
|Permissible angles under I.S.6: as follows||Table 6|
|Nominal Size mm||Permissible Angle|
|150||90°, 45°, 22½°|
NOTE: All chamber sections are to be stored vertically on site to prevent rolling.
The cover slabs, which are all reinforced, have a different thickness for different diameters. All are provided with a 600mm (min) diameter opes and a socketed base which allows a butyl sealant joint to the top chamber section.
|Cover Slab Dia.||Overall Approx. Thickness||Effective Approx. Thickness||Approx. Weight (kg)|
I.S. 420: 1989, I.S. 420: 2004 and ISEN 1917 incorporates routine water absorption tests, works proof load tests, maximum load tests, cube crushing tests, cover to reinforcement, complete manhole hydrostatic test and installed step tests. Our Quality Control Team carries these tests out daily to ensure compliance to the relevant standards.