PROVISION FOR THERMAL MOVEMENT
All plastic soil and waste systems move with changes in temperature.
It is vital to accomodate this movement when making push-fit joints.
An expansion allowance is also necessary in solvent weld systems. As
installation of a system progresses, a continuous check should be made
to ensure that the expansion allowance has not been lost.
PIPE SUPPORT
All soil and waste pipes must be securely fixed, but not so rigidly
as to prevent thermal movements. Distances between pipe supports are
determined by pipe material, diameter and gradient.
Two types of bracket are available for 110mm pipe:
BS407 has two side fixing holes: BS438 has three centrally positioned
holes, and is especially suitable where only narrow surfaces are available
for fixing.
PIPE ROUTING
The flow through discharge pipework is most efficient where, in branch
pipes in particular, the pipe routing is as straight as possible, and
bends where necessary are of generous radius to assist smooth effluent
flow. Minimum bend centre line radii for components are given in the
various British Standards.
OVERFLOW DISCHARGE
Overflows can discharge into soil stacks or branches, in which case
the discharge must be through a trap and tundish.This allows appliance
overflow to be detected, and prompt maintenance carried out. Where the
discharge is not into the soil system, it must be designed such that
there is no potential for damage to the building fabric from water.
TESTING
FINAL INSPECTON
On completion, the sanitary discharge system should be meticulously
inspected to ensure that requirements of relevant codes of practice
have been adhered to. No cement droppings, rubble or other objects should
be left inside the system and no jointing material should intrude into
the bore. When fully inspected, the system can be pressure tested.
AIR TEST
The pipes, fittings and joints should be capable of withstanding an
air test of positive pressure of at least 38mm water guage for at least
3 minutes. During this time every trap in the system should maintain
a water seal of at least 25mm. Chemicals released by smoke test cartridges
adversely affect plastics materials, particularly PVCu, making this
method unsuitable.
MAINTENANCE
Provided that the system has been designed and installed correctly,
mimimal maintenance will be required. Security of retaining clips, brackets
and joints of exposed sections of systems should be inspected on at
least an annual basis and any faults rectified to ensure correct functioning
is not impaired.
Blockages, provided not due to poor design, may occur through misuse.
Blockages can be cleared using flexible or roller type rods.The equipment
used by drain and pipe cleaning contractors is generally suitable.
SAFETY
Hazard data sheets dealing with Brett Martin solvent cleaner, solvent
cement and lubricants are available on request.
