185
foam injection device shall be per the foam injection device manufacturers requirements, but in no case
lower than 1 bar.
P.3.2 Foam injection pumps shall not work under suction conditions.
P.3.3 Foam pumps shall be installed with a pump casing relief valve. Casing relief valve shall be set to
open after pump pressure is 1 bar higher than the design limit of either the pump or the system piping
network, whichever is less. The discharge of the casing relief valve shall not be piped to the suction side
of the foam pump. The discharge of the casing relief valve may be piped or to the liquid level of the foam
storage tank.
P.3.4
An approved pressure sustaining valve shall, if required by the injection device manufacturer, be
installed in the discharge side of the foam injection pump and shall be designed to discharge below the
liquid level of the foam tank. The pressure sustaining valve shall be calibrated to open where low water
flow rate through the main stream of the proportioned is present and to close where large water flow
rate is present during proportioning. Piping shall be adequately sized on the supply and discharge of
pressure sustaining valve for full flow capacity.
P.3.5 The pipes up- and downstream the foam injection pumps shall be fitted with flushing connections.
No water shall flow back in the foam tank.
P.3.6 Foam pumps shall start by automatic means. Foam pumps shall require weekly testing.
P.3.7
Suction pipes with pure foam agent shall be designed in such a way that the NPSH available is at
least 1m higher that the required NPSH of the foam pump.
P.4.1 Foam agents shall be approved by the authorities.
The foam agent shall be selected appropriate to the materials to be protected and the foam injection
device.
P.4.2 The water shall not have any ingredients which are not compatible with the foam agent.
The quantity of the foam agent is determined at design flow rate by the operation time and the design
concentration.
Unless specified elsewhere, the quantity of foam agent shall allow a continuous operation of the system
for at least 30 min.
P.4.3 The quantity of foam agent may be reduced to 50 % if the premises have a recognised fire brigade
and the same quantity of foam agent can be feed in the foam tank in a time not exceeding 15 min. The
fulfilling of this requirement shall be approved by the authorities in the planning state of the installation.
P.4.4 Only the same type of foam agent of the manufacturer shall be used for refilling. Mixing of
different foam concentrates is forbidden.
P.5.1 Foam tanks shall be approved by the authorities.
Depending on the type and quantity of foam agent a security pool can be necessary.
To Next Page
Loading...