Chezy PP Inspection Chambers

Plastic sewer pipes have been used all over the world. Their contribution to public health and sanitation is excellent and they have out performed traditional material.

PP Inspection Chambers
Preformed Plastic Inspection Chambers have been widely used in Europe and the United States for the past twenty years. The Chezy PP Inspection Chambers have excellent structural integrity, good design and operational performance, water tightness and exceptional resistance to chemicals.

ADVANTAGES OF THE CHEZY PP INSPECTION CHAMBER OVER THE TRADITIONAL CHAMBER

Chezy Chamber	Traditional Chamber
• High compressive strength and is fully functional even with 2 inches (50 mm) of ground settlement or flooding	• Chamber will collapse and crack on ground settlement or flooding
• 100% water and air tight connections, completely leak proof	• Leaking chamber (bad workmanship), leaking pipe connections to traditional chambers (different types of material being bonded by cement only)
• Long life, will last for hundreds of years, very chemical resistant, no effect on chamber by H2S or sewage	• Corrosion of chamber by H2S, leading to attack of the chamber wall and eventual collapse
• Very smooth inner walls, no cockroaches or vermin	• Rough inner walls, ideal breeding ground for cockroaches and vermin
• Very little labour required (80% less) – Very ECONOMICAL	• Very labour intensive – EXPENSIVE
• Aesthetically pleasing. Very strong and UV stabilized locked down cover	• Ugly cast iron cover. Easily stolen and will definitely rust and crack after long term use

The Chezy PP Inspection Chamber is light weight and more economical than the traditional chamber, their functional performance is excellent.

Load factors on chambers vary according to type of soil, compaction during installation and groundwater. An important function of the chamber is to resist these factors and to maintain the hole in the ground.

The Chezy PP Inspection Chamber has under gone the following tests.

MECHANICAL CHARACTERISTICS OF CHEZY PP INSPECTION CHAMBERS.

Characteristic	Requirements	Test Parameters		Test Method
Characteristic	Requirements	Parameter	Value	Test Method
Stiffness of riser shaft	No cracking, stiffness > 0.7 kN/m2	Shall conform to EN ISO 9969		EN ISO 9969
Vacuum requirement for resistance of PP Inspection Chambers to ground and water pressure when installed	No damage to the structure that could be deemed to impair its function	Test temperature Test period Internal negative pressure	(23 ± 2)°C 100 h -0.3 bar	EN 1277:1996 Condition A
Resistance to vertical loading	Deflection of horizontal dimensions not to exceed 6%. Deflection of cover shall conform to clause 4 of EN 1253-1:2003,< 0.4% No cracking	Force for class L	15 kN	Clause 4 of EN 1253-2:1998

For the integrity of the chamber, loads , and should be withstood. The ring stiffness of the shaft is the most important parameter in the chamber, it should not collapse under the load of ground and ground water.

The graph (ground water level is 0.5 m below the surface) shows the maximum allowable depth (H) for chambers when buried in sand, clay and in very weak soils. The following buckling formula was used:-

From the graph, it can be seen that a ring stiffness of 1 kPa is sufficient for sandy and clay soils. The shaft would buckle if the chamber is more than 2 meters deep in soft and water like soils. Experience in Europe has shown that a ring stiffness of 2 kPa is a safe limit, in all ground conditions.

The capacity of a sewer system will be determined by the diameter and gradient of the piping system. Foul drains are normally designed to carry peak discharges at less than full flow (usually to a max. of 75%) to allow for ventilation of the system.
Recommended gradients for water are shown below (minimum flow velocities of 0.76 meters/sec should be used to avoid the possibility of solid waste being deposited).

Pipe Size	Min. Gradient	Max. Capacity (litres/sec)
110 mm	1:80	6.3
160 mm	1:150	15

Calculation of Flow Rates by Using Discharge Units

Appliance Discharge	Unit Value (D)
Wash Basin	0.5
Bidet	0.5
Shower	0.6
Urinal	0.8
Bath	0.8
Sink	0.8
Dishwasher	0.8
Washing Machine	0.8
WC	2.0

For general calculation purposes (BS EN 12056: Part 2) the above discharge unit values can be used. Flow rates (litres/sec) in the pipe can be calculated as follows:

1. Excavate to the required depth allowing for working space around the Chezy PP Inspection Chamber.

2. Install the chamber base on at least 100 mm compacted granular material (10 mm max particle size) or on a 4 inch concrete slab (for grounds having a high water table).

3. Chamfer incoming pipes (ensure that chamfer angle is 15°) and push into sockets in the body of the chamber. Ensure that the pipes and sockets are free of dirt and debris. Sealing is achieved by rubber rings. Plug off unused sockets (2 plugs are provided for every chamber).

4. Connect riser pieces to the required height and place the collar and cover section to achieve the desired height (finished ground level). The sealed ABS cover and frame allows for 100 mm telescopic adjustment.

5. Back fill using as dug or granular material.

6. Ensure that all four screws in the cover and frame are screwed down.

7. On completion of the project, if height or direction of cover and frame needs to be changed. Dig to the depth of the collar and pull collar up for additional height or rotate collar to the required direction.

8. On completion of the project and before handing over to the owner, remove the plastic sheet on the cover.

9. During installation, ensure that there is a 2 inch overlap of all sections joined (Riser to body, riser to cover, etc). This is to allow for ground settlement.

Polypropylene Inspection Chamber with anti-slip UV stabilized ABS cover and frame, SIRIM certified and conforming to EN 13598-1 and BS EN 1253-4 for load strength of 300 kg/1500 kg. Central channel in chamber shall be 150 mm and minimum outlet size from chamber is 150 mm. All joints to and from chamber are to be rubber ring sealed.

150 mm x 150 mm concrete surround required for support of cover and frame where the PP Inspection Chamber is being installed on a driveway subject to light vehicle traffic. Selected site material free from stones larger than 25 mm. 100 mm layer of compacted granular material above crown of pipe and 100 mm layer of 10 mm granular material below main channel of PP Inspection Chamber. 100 mm (4”) concrete slab for ground with high water table.