2 replies to this topic

[sukanta87]

Hi All,

This is first time am involved in fire fighting network design for a NG process plant. Before that had only the operational and constructional experience on this system. Some of the queries underlie here for fire fighting by water:

1. How many fire hydrant should be installed in the whole plant area? The distance between two hydrant should be similar in the whole area? Or the distance varies regarding main process area, tank area, oil loading area etc? Is it needed to check the vendor's catalog firstly to determine the throw range?

2. What should be the criteria for sizing the main fire water pump? As it mainly depends on the number of fire hydrant will run at a time and the respective flowrate, the consideration is important to run the number of hydrant at a time. If there is 20 hydrants in the plant area, the main fire water pump sizing should be done for the flowrate requred for 20 hydrants running at a time or something like 5 or 10 hydrants running at a time?

3. Deep well pump (submersible pump) can be used for the fire water reservoir filling. The thing is what should be the time required for the filling up the water reservoir like 4 hrs/10 hrs/30 hrs/ ...?

 

4. What are the standards for practicing this work? Which part of NFPA is dealing with it?

 

 

Thanks in advance for your time.
 

 

[Art Montemayor]

sukanta87:

 

As an ex-plant manager, I can reflect back on my experience and easily come up with some comments that may help you out:

 

You should be in direct contact and communications with the parties that are directly, legally, and financially affected by your circumstances:  your local Fire Marshall and your insurance company.  In the event of a fire in your plant, you must abide by the requirements set forth by your local community firefighters (not your in-plant firefighters) in order to safeguard their interests.  Your local Fire Marshall is usually the person responsible for making sure the local community is safely protected.  Your insurance company will also have minimum requirements for you to meet in accordance with your coverage.  Both entities will probably always refer to a recognized firefighting standard such as the NFPA.  Detailed knowledge of such documents as NFPA 20 and 25 is usually required.  Find out what local standards apply.

 

The minimum required firewater flow rate is something that is fixed by the type and number of processing units and their equipment layout incorporated in your facility.  Normally you should determine this by a careful and certified study and calculations based on your facility, the risk factors, the location, the availability of external assistance, and other important safety factors.  A firefighting survey of your facility is usually a priority requirement.  You must demonstrate the ability to successfully fight the worse credible fire hazard in your property or show the ability to contain it.

 

I would not expect to locate fire hydrants in accordance with a “standard”.  I would expect that to be determined by a detailed study and survey of your facility and its requirements – on an area-by-area basis.

 

The use of a deepwell as firewater source may not be approved locally if you cannot show that the well’s dynamic, maximum flow rate during the dry season is sustained and available.  A second, independent well or other back-up source will probably also be required in the event the deepwell pump fails to operate when needed.  If an electric motor drive is proposed, then an independent and safe supply of energy has to be assured to have the pump fully capable to perform at any moment.

 

There are other important factors to consider, but the above are some of the primary important ones.

 

 

[sukanta87]

Hi Art,

Thanks for your comments and sharing practical experiences.

The above NFPAs are for installation, inspection, testing and maintenance mainly. Both local and international Standards for detail engineering are needed to support the considerations. The point mentioned regarding back-up source for firewater is nice to have. Some other documents like IPS 220, IPS 240 (Fire Water Pump Systems), API 2030, API 2001 etc may help for design considerations.