To boost both performance and energy efficiency, BAA
Heathrow has recently replaced its deluge pump system
with a state-of-the-art system designed and fabricated by
AxFlow Windsor

At London’s Heathrow Airport,
training fire crews is an almost
constant activity, which is why it has
a purpose-designed fire training rig
constructed from steel to the same size as a
Boeing 747. Packed full of safety sensor
devices it is a pretty expensive piece of kit
with a replacement price tag of around
£10m. So, when it is set on fire during
training exercises, putting out the fire has to
be fast and effective in order to ensure safety
for the fire crews undergoing training and to
preserve the integrity and fabric of the rig.

In the interests of ensuring optimum
performance and attaining greater energy
efficiency, BAA Heathrow has recently
replaced its existing deluge pump system
with a new pump system designed and made
by AxFlow Windsor. The new unit comprises
four Lowara 92SV3/2AG185T vertical
multistage pumps with 18.5kW motors. The
pumps have been sized for a duty of
1746L/min @ 46.2m/hd giving a total flow
rate of 5238L/min with three pumps running
and one being used as a spare. AxFlow
Windsor selected these pumps due to their
high efficiency and compact footprint as they
had to fit four pumps into the space occupied
by one (albeit larger) pump.

“The existing pumping arrangement was
using one pump and a 110kW motor,”
reports Richard Maher at AxFlow Windsor.

“This ran at full speed regardless of the
demand on the system, which could vary
between filling the fire tenders’ on-board
tanks to a full deluge of the training rig itself.

The new system uses one 18.5kW pump
when filling the tenders and three 18.5kW
pumps to fully cool the rig, so there is a
considerable saving in power consumption.

The pumps are controlled by ABB ACH550
inverters so the running speed can be set to
match the duty exactly.”
Fire training is held on a regular basis with
each session ranging between one and two
hours. The rig is set on fire internally and
externally with LPG, and the fires last for around
three minutes. The purpose of the deluge
pumps is to cool the rig and to control the
overhead water fill on the fire training ground.

The deluge starts before the scenario and
works through the period of the fire and then
for about one minute after the fire has stopped.

Ian Jolly, BAA Water Services, explains
that when the full test of the new pump
system was carried out at the fire training rig
all the valves were opened to produce a full
deluge and the pumps succeeded in sending
water to all parts of the rig.

Jolly says: “Under test the pumps were
slowly ramped down from full speed to try
and see at which point the head could not be
achieved. With three pumps running the
deluge was achieved, but with two the head
was not reached. This gave a redundancy of
25% and still met the requirements of the rig.

With all four pumps running the filling boom
was also opened. The flow was maintained
to the rig with the required head, enabling a
tender to be filled at the same time as the rig
was being used. With three pumps running
the boom robbed the head to the rig.”
For the test, each pump was left running
at a full speed of 50Hz and at this speed each
pump was pulling 33A at 17.5kW. In total
the pumps are pulling 132 Amps, 70kW.

Limiting the current keeps the pumps below
the 200A threshold of the supply fuses, with
each pump set at 48A.

The current draw is just over half of the
previous installation with the power reduced
by the same factor. The use of variable speed
drives mean that the pumps pull no more
than the full load current on start up. The
redundancy of 25% means that servicing or a
breakdown can be attended to without loss
of service to the facility. The redundancy
also means that the rig and boom can be
used in conjunction with each other.

“In summary the water supply system for
the rig is now fit-for-purpose, providing
greater flexibility, maintainability and power
reductions,” says Ian Jolly. All-in-all, an
excellent result all round.”