Page 593 - The City and Guilds Textbook: Plumbing Book 1 for the Level 3 Apprenticeship (9189), Level 2 Technical Certificate (8202) and Level 2 Diploma (6035)

Chapter 9 Sanitation systems

Tubular traps

Tubular traps can take several different forms.

INDUSTRY TIP

‘P’ traps and ‘S’ traps are named after their shape. A ‘P’ trap is used where the waste
pipe is installed from the appliance horizontally, directly through the wall and into a gulley
or stack. The ‘S’ trap, because of its shape, will allow pipework to be installed vertically
downwards from the trap into a waste pipe serving a number of appliances or into an
underfloor waste pipe.

● Swivel traps: often used on new work and appliance replacements, they
have a union connection in the centre that allows the trap to swivel
360°. This facilitates multi-positioning, allowing many different pipe
connection options. They can be either ‘P’ trap, ‘S’ trap or running trap p Figure 9.68 ‘P’-type swivel
types. traps
● Running traps: the idea behind a running trap is that an appliance or group
of appliances can be trapped away from the appliances themselves, the trap
being installed on the waste pipe run. They are sometimes used where space
to install a trap at the appliance is limited.
● In-line traps: specifically designed with washbasins in mind, the in-line trap
is essentially an ‘S’ trap where both inlet and outlet are in line. They allow
washbasin wastes to be completely hidden behind a pedestal, but can be
restrictive and tend to block easily.
p Figure 9.69 ‘S’-type swivel
● Washing machine traps: generally used for appliances such as washing traps
machines and dishwashers with a ‘P’ trap configuration. They have an
extended neck to facilitate a washing machine/dishwasher outlet hose.
l Bath traps: two different types are available. One is a swivel type with
a 50 mm trap seal and the other has a 38 mm trap seal. They are made
specifically to be fitted in the restricted space under a bath or shower
tray.

Bottle traps
Bottle traps are used on washbasins because of their neat appearance. p Figure 9.70 Running trap
However, they can be very restrictive to the flow of water. There are certain
appliances where a bottle trap is not suited, such as on a kitchen sink or a
urinal, where they block easily. Regular trap cleaning is important to maintain
an adequate water flow. There are two different types:
1 Bottle traps: used with washbasins and bidets. Access for cleaning is via the
bottom of the trap, which unscrews to facilitate the removal of blockages.
2 Shower traps: although not strictly a bottle trap, the operating principle
of the shower trap is exactly the same as that of a bottle trap. The main
difference here is that the trap seal depth is much less than 75 mm and
access for cleaning is through the grille on the top of the trap rather than
underneath. p Figure 9.71 In-line trap

581

9781510416482.indb 581 29/03/19 9:07 PM