| DUK1 - Anti-vacuum valve combined with a single check
valve. Suitable for protection against; backpressure
category 2 and back siphonage category 3. A mechanical device
comprising an anti vacuum valve with a single check valve
located upstream. No known manufacturer of this product to
date
EA - Verifiable single checkvalve
Suitable for protection against backpressure category 2,
and back siphonage category 2. Installed in the main feed
prior to the appliance. A mechanical device that can be tested
in situ; usually via test ports upstream and between the mechanical
elements of the device. It will allow water to flow upstream
to downstream but not in the reverse direction.
EB - Non verifiable single checkvalve
Suitable for protection against; backpressure category 2,
and back siphonage category 2. Installed in the main feed
prior to the appliance. A mechanical device that will allow
water to flow upstream to downstream but not in the reverse
direction.
HA - Hose union backflow preventor.
Suitable for protection against; backpressure category 2
and back siphonage category 3. Simple installation of a backflow
preventor to an existing hose union or outside tap. Only permitted
on existing installations. A mechanical device for fitting
to the outlet of a hose union tap and consisting of a single
check valve with air inlets that open if the flow of water
ceases.
LA - Pressurised air inlet valve.
Suitable for protection against back siphonage category 2,
not acceptable as a backflow prevention device. An anti vacuum
or vacuum breaker similar to a type DA but suitable for conditions
where the water pressure at the outlet of the device under
normal conditions is greater than the atmospheric pressure.
Application tends to be limited to locations where waste is
acceptable e.g. gardens.
LB - Pressurised air inlet valve combined with a
check valve downstream
Suitable for protection against; backpressure category 2
and back siphonage category 3. Same as type LA but single
check valve is located downstream. Application tends to be
limited to locations where waste is acceptable e.g. gardens. |
