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.
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.
Guest Author - Technical