List of 8 Beneficial Changes made in the Standard of Fire Pumps over the Years
Standards
governing the design of fire pumps are updated every few years. This is done to
ensure that these address the new design challenges and overcome the
shortcomings of previous designs. In this light it would be quite interesting
to look back over the last 10 years and gauge the important changes that have
happened in these standards. A close analysis will reveal that the designs have
significantly evolved for the better; these now ensure superior performance and
safety.
Here we
will look back and see some of the major changes in the standard of fire pumps
and their resulting benefits.
1.
Torsion analysis for right angle gear drives
For
vertical shaft pumps that are right angle gear driven, a torsion analysis is
mandatory. This helps to identify and eliminate any damaging stresses or liner
resonant frequencies created from the operating speed range of the rotating
equipment. This will help avoid any potential damage to the pump equipment.
2.
The right diesel fuel and the right rating
While
most fire pumps are rated for use with DF2 (Diesel fuel 2) but for emission
reasons some states recommend use of DF1 (Diesel fuel 1). If DF1 is being used
in a pump rated for DF2, then the horse power rating of the pump should be
lowered by 10 percent and this must be considered while selecting the right
capacity for your fire pump.
3.
Minimum fuel level in a tank
Fuel tanks of fire pumps should always be full ideally, but in case the
fuel level goes down it should never drop below 67 percent of the fuel tank
capacity. For this purpose fuel indicators should be installed.
4.
Definition of reliable power supply
Fuel
pumps need to be powered by a reliable power supply and the changes to the fire
pump standards have made the definition of reliable power supply even more
stringent. The power supply will be considered as reliable only if the
shutdowns in the source power supply did not extend beyond 4 hours in the year
prior to plan submittal. There have been no power outages for reasons of grid
failure (for reasons other than natural disaster). The power to the pump is not
provided by overhead conductors. The disconnect switches and protective devices
installed as per the recommended standards.
5.
More explicit requirement criteria for very tall buildings
The
recent changes introduce a new concept which defines the requirement of very
tall buildings. Those high-rise
buildings which are beyond the
reach of pumping capabilities of
the existing fire department apparatus are considered as very tall buildings.
Due to the elevation and friction loss the required pressure (100 psi) cannot
be generated at the top floors of very tall buildings. The standards therefore mandate the implementation of
additional protection features and performance based criteria for fire pumps.
The new
standards mandate the provision for additional water supplies and redundancy of
fire pumps. In such cases tanks are used to reach the sections of building
which are otherwise out of reach of the fire department equipment. These tanks
should be equipped with automatic fill valves in addition to the manual fill
valve. The tank size should be large enough to meet the entire fire protection
demand of such buildings.
6.
No “Other Pumps” can be used for fire protection
Until
recently most standards had a reference for “Other Pumps” which has been
removed. This has been done to empha size that only fire pumps listed in the
standards can be used for fire protection. Other pumps basically allowed use of
pumps with design features other than discussed in the standards to be used
which will not be the case going forward.
7.
Access to the pump room
The
fire department needs to be consulted for designing an access to the pump room.
Standards were updated and mandated that pump rooms be directly accessible from
the outside. The enclosed passageway should have a 2 hour fire resistance.
8.
Additional protection for pump room with diesel fuel
Pump
rooms with diesel fuel will be considered extra hazardous and should be
accordingly protected. Abundant quantity of water should always be readily
available in the room. Diesel tanks should always be mounted on non-combustible
supports.
Other
changes
There
have been many other changes in the standards. All these changes are intended
to make the fire protection system more reliable and robust at Aipumps with every passing year.
Article by
Murnal Kharti
Guest Author - Technical
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