Installation
Installation
- Bracket distribution with flexible installation With expansion sockets
Apart from brackets at fixed points, all brackets must be support brackets. Another solution is to select (threaded) support clamp suspension legs of materials and dimensions that will bend to follow the changes in length. This does however open the way to undulation of pipework. This last point need not present a functional problem provided the fall is not reversed. It is however often regarded as less pleasing to the eye. The change in length ( L ) for a particular length of HDPE pipework and the required length (L) of a flexible section for various temperature differences can be read off from illustration 7.7.
- Flexible installation with flexible connectors
For horizontal pipework this method is preferred over expansion sockets. In general only a small change in alignment is required (illustration 7.4). For long sections of pipework it may be necessary to create horizontal "jumps" (illustration 7.5). If this is appreciated in good time there need be no difficulties with any other pipework or cables. As with expansion sockets, support brackets are used, with clamping brackets for fixed points. The permissible pipe length from the fixed point (clamping bracket) to the flexible section is dependant on the bending the flexible section can take. The pipes should be bent so as to provide the maximal flexible length. This gives clarity in assembly and maximum flexibility. Halving the permis- sible clamp separation distance will give the permissible length for the flexible section (illustration 7.6).
With expansion sockets the clamping brackets must always be located at fixed points. The distance between these is divided, taking account of the maximal bracket separation, and the support brackets placed accordingly. With flexible connectors The brackets are to be placed at the maximum permitted distance from the nodes (branches, bends etc), see illustration 7.6. The distance between these is divided, taking account of the maximal bracket separation.
Illus. 7.4 Minor changes in alignment to create flexible pipe sections.
7.2.2 Rigid installation (HDPE)
- Bracket separations with flexible installation
Illus. 7.7 Relationship between temperature difference, freely moving pipework length, changes in length and length of flexible section for various diameters of HDPE pipes.
In the case of rigid installation the system is installed in such a way that changes in length cannot occur. The forces genera- ted are transferred to the building structure by shell brackets, fixed point brackets and suspension constructions. Rigid installation is only required with HDPE. A rail system or half-shell bracket support system is always required with rigid installation. With shell brackets alignment is achieved by securing the pipe to the shell bracket at the location of the 0.2 metre overlap, using a clamp or 2 strong Tie raps. The pipe is also fixed to the shell brackets every 10 x D (min. 0.5 m; max. 1 m) with Tie raps or bands.
Clamp separations are selected so that the pipe does not sag enough to prevent proper emptying even when hot water is carried. The pipework must still be able to slide through the support brackets. The pipework must also be prevented from excessive sagging for aesthetic reasons. From strengh point of view horizontal pipework in HDPE can be suspended with clamp separations from 20 to 25 x D. HDPE waste pipework can be installed with or without half round shell brackets (illustration 7.8). The shell brackets are in galvanised steel and may be black. Shell brackets are used with horizontal pipework where neat, straight runs are required, without sagging. With "hot" pipework ( T = 60°C) shell brackets are necessary with HDPE pipes. Shell brackets are often used with small diameters to allow a greater separation between brackets. Since the pipe cannot easily slide through the shell brackets, rigid mounting is always used with half-shell brackets (see 7.2.2).
Illus. 7.5 Horizontal "jump" to create flexible section in long stretch of horizontal waste pipework.
7.8 System without/with shell brackets.
26
27
Illus. 7.6 Flexible installation with flexible connectors, and distribution of brackets.
Made with FlippingBook Annual report