Hi taoxianwen123:

You mentioned some points that I have not had time to address.

What is the meaning of "private fire protection"? I could not find it but I found some definitions (NFPA Glossary of Terms) related to phrases which include the word "private" and I am sharing them.

I hope you conclude that private fire protection is what is built on private property to detect, control and extinguish fires. Properly designed, It is suitable to protect oil & gas plants, oil refineries, private universities, nursing homes, theaters, etc. The point here is that it is built on private property, with private funds.

Having said that, if private fire protection can not count on public waterworks for a reliable supply and there is a need for storing water, different options will have to be assessed as well as many design guides will be consulted.

Major oil and chemical companies have their own standards. Same comment applies to major engineering firms. I am not saying that NFPA 22 should be used. I bet that you can think of other sources of information that fit better your needs; however, the post was started with the question "how long it required to refill the fire water tanks after a fire"? and NFPA 22 popped in my mind.

NFPA 22 is a widely known standard in the U.S. and the NFPA is recognized worldwide. Once it has been decided to use this standard for designing elevated tanks on towers or building structures, water storage tanks that are at grade or below grade, and pressure tanks, it does not matter what kind of property will be protected. Properly designed, it will be suitable to protect oil & gas plants, oil refineries, private universities, nursing homes, theaters, etc.

You have concerns related to water treatment. According to my experience, oil & gas plants/oil refineries, firewater is raw water, maybe with some minor treatment. It is not drinking water or boiler feedwater. I agree that water has to be treated for some uses. Unless, the quality of firewater is too bad or there are some requirements (Government, company policies, etc.) that I do not know, I see no need for special treatment.

I checked the water quality requirements in the NFPA standards that use water for protection. This is what I found:

NFPA 13 (2010), 23.1.5 Water Supply Treatment: Water supplies and environmental conditions shall be evaluated for the existence of microbes and conditions that contribute to microbiologically influenced corrosion (MIC). Where conditions are found that contribute to MIC, the owner(s) shall to treat the system using one of the 4 methods given in that standard. Water supplies and environmental conditions shall be evaluated for onditions that contribute to unusual corrosive properties. Where conditions are found that contribute to unusual corrosive properties, the owner(s) shall notify the sprinkler system installer and a plan shall be developed to treat the system using one of the 4 methods given in that standard.

NFPA 11 (2010), 4.2.1.1 Quality: The water supply to foam systems shall be permitted to be hard or soft, fresh or salt, but shall be of a quality such that adverse effects on foam formation or foam stability do not occur. No corrosion inhibitors, emulsion breaking chemicals, or any other additives shall be present without prior consultation with the foam concentrate supplier.

NFPA 16 (2007), 6.1 Water Quality: Water supplied to foam-water systems shall be compatible with the foam concentrate to be used. Water that contains solids likely to clog orifices in discharge devices but that is otherwise acceptable for making foam shall be permitted to be used after passing through line strainers.

NFPA 24 (2002), 5.8 Penstocks, Flumes, Rivers, Lakes, or Reservoirs: Water supply connections from penstocks, flumes, rivers, lakes, or reservoirs shall be arranged to avoid mud and sediment and shall be provided with approved, double, removable screens or approved strainers installed in an approved manner.

I found no special requirements for water quality in NFPA 14 (2007), NFPA 20 (2010) and NFPA 22 (2003). I hope I did not miss them. Same comment for NFPA 15 (2007); however, we know strainers are needed to avoid the plugging of nozzles.

Only NFPA 13 addresses corrosion in some detail. Notice that some of the methods proposed to control corrosion could be destructive for the foam concentrates (NFPA 11).

Let's discuss about the refilling time. I do not know if 8 hours is to tight. It is just the requirement of NFPA 22, mandatory if the standard will be used for design. Otherwise, it is just a reference.

I disagree that the refilling time is based on the time interval that another fire happens again. How can I know if another fire will happen in 8 hours or any other time, say 48 hours? How can anybody know this? Maybe it is based on statistics. If so, I hope they are related to the oil and chemical industries.

Say that the worst scenario fire ocurred and no water is left. I would hope to have my fire protection system available as soon as possible. Even if the plant shut down, there will be maintenance crews removing debris and trying to get the plant back on business. We know that fires occur during those activities.

I have a hard time seeing the refilling time of 48h (large communities) as a reference for oil&gas plants. I believe that most of the time they are not comparable.

Finally, I totally agree with Nabilia's post #6. I also have that experience. A backup system is needed and it will help you in choosing a more flexible amount of time for refilling.

Well, I see this Forum as a means for sharing experience and ideas. Other members are welcome to contribute.