Installation Requirements
These fittings need to be installed in
accordance with the following Installation
Requirements and Notes (IRN) to ensure
they meet the requirements of the Water
Supply (Water Fittings) Regulations 1999
and the Scottish Byelaws 2004.
IRN R001: See text of entry for Installation
Requirements or Notes
.
IRN R040 - Schedule 2-15 (1): The
fitting shall be installed so that its outlet
discharges above the spill-over level of
any fixed appliance as indicated below:-
For backflow protection in domestic or
installations up to, and including, Fluid
Category 3.
If the fitting cannot be installed as
indicated in the table opposite it shall be
installed as either a or b below:
a: with an approved double check valve
assembly or some other no less
effective backflow prevention device
immediately upstream of the inlet.
b: so that it draws water by gravity only
from a cistern, or cylinder having a
permanently open vent pipe, and the
distributing pipe supplies no other fitting
(other than draining tap) at a lower level.
For backflow protection in premises or
installations up to, and including Fluid
Category 5.
The vertical distance of the outlet above
the spill-over level shall be not less than
20mm or twice the diameter of the inlet
pipe to the fitting, which ever is the
greater. If the fitting cannot be installed
as indicated it shall be installed with a
backflow prevention arrangement
suitable for the Fluid Category.
Size of tap or
combination fitting.
Vertical distance
of outlet above
spill-over level.
1. Not exceeding 1/2
in
20mm
2. Exceeding 1/2 in
but not exceeding
3/4 in
25mm
3. Exceeding 3/4 in
70mm
12
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