DESIGN MANUAL PARKS & RECREATION FACILITIES DIVISION ABU DHABI MUNICIPALITY

PRFD - Design Manual for Irrigation 120

PART 11 VALVE CHAMBERS

1 General

The following items must be considered in siting and design of valve chambers:

Siting of chambers in carriage ways should be avoided; they should be preferably in the road verge or in the footway, utility corridors must be respected

All chambers must be designed of reinforced concrete or of solid concrete blocks

Foundations to chambers must be of concrete and must finish flush with the chambers sides unless specifically otherwise required

The bottom of the chamber must have a minimum slope of 2%

The bottom of the chamber must have suitable sump holes covered by aluminium grating cover to allow drainage soak away, with the exception of air valve chambers

A GRP ladder for access must be provided in chambers of more than 1.0 m of height

Entry to deep manhole chambers (> 2.5 m of height) must be by means of one or more caged ladders.

Two flexible joints, with a "rocker pipe" should be provided on either side of the chamber to avoid damaging pipework in case of differential settlement. Such joints are not required in the case of PE pipe which is flexible in itself

There should be sufficient working space and clearances inside valve chambers, proper access arrangements and gravity ventilation by employing vent pipes

A minimum clearance of 500 mm from the walls of the chamber to the equipment must be provided

A minimum clearance of 500 mm from the walls of the chamber to the joints must be provided

A minimum clearance of 400 mm from the floor of the chamber to the invert level of the pipe must be provided

All chambers must have a removable cover with lifting hooks for easy installation and repair. The chamber construction and cover must facilitate the lifting of equipment

All pipework within valve chambers must be carbon steel or ductile iron and the transition from one type of pipe material to another should be done directly outside the valve chambers

In cases where non-restrained pipe systems are used the chamber must be designed to take the full thrust when the valves are closed. In such cases pipework must be fixed to the chamber walls by means of puddle flanges

All the equipment must be easily dismantled. Appropriate dismantling joints must be provided

All the equipment must be properly fixed and supported. Thrust blocks and supports for valves, elbows, tees, etc. must be provided

2 Flow Meter Chamber

In general, flow meter locations must facilitate the day to day system monitoring and allow the ability to calculate the water balance

DESIGN MANUAL PARKS & RECREATION FACILITIES DIVISION ABU DHABI MUNICIPALITY

PRFD - Design Manual for Irrigation 121

Flow meters outside pumping station buildings, and associated data loggers, must be housed in suitable, underground concrete chambers

Equipment that may create flow disturbances, such as isolation valves or reducers, must not be placed next to flow meters. The minimum distances from manufacturer’s data sheets must be respected

In general, flow meters chambers must be composed by an electromagnetic flow meter, associated data loggers, dismantling joint and pipework.

Isolating valves located upstream and downstream the flow meter must be provided in separate chambers. In such cases the provisions for line shut-off chamber must be followed

The flow meter must be anchored on the upstream side having a dismantling joint on the downstream side that permits its removal

If the size of the flow meter is smaller than the pipeline properly designed reducers must be used to minimize the head losses. In general, the reducers must be placed outside the chamber

Flow meters designed for flows above 10,000 m3/day require in-situ wet calibration, as per RSB Wastewater Monitoring Code. Provisions must be taken into account to allow the in situ wet calibration.

3 Line Shut-off Valve Chamber

In general valve locations must facilitate the maintenance of the irrigation system

Valves outside pumping station buildings must be housed in suitable, underground concrete chambers

In general, diameter of the valve should be same than the diameter of the pipeline. If the size of the valve is smaller than the pipeline properly designed reducers must be used to minimize the head losses. The reducers must be placed outside the chamber

In general, line shut-off valve chambers must be composed by a gate valve (up to DN 600) or butterfly valve (above DN 600), dismantling joint and pipework

The valve must be anchored on the upstream side having a dismantling joint on the downstream side that permits its removal

4 Air Valve Chamber

Air valves should be placed inside purpose built chambers

Air valves outside pumping station buildings must be installed in a reinforced concrete chamber, with two air vents

The ground of the chamber must be gravel to allow effective drainage of water leaking from the valve orifices

In general, air valve chambers must be composed by an isolating ball valve (up to DN 80) or gate valve (above DN 80), double function air valve with automatic air release and pipework

5 Washout chamber

The washout concrete chamber must consist of dry and wet well

The wash out assembly must include an invert level tee, a 90° elbow, a manual gate valve and a dismantling joint, housed in the dry well