Fire Pump: What Rated Flow Capacity?

To determine the size of your fire pump, we have to find how much water do we need. We need to find the largest fire water demand. How to get that value will be discussed in a separate  post.

Let's assume that our largest fire water demand needs the following:

 - 4 hose streams (946 lpm x 4 = 3,784 lpm)

 - 2 fire water monitors (1893 lpm x 2 = 3,786 lpm

 

The total flow rate is 7,570 lpm. These fire fighting equipment are typically rated to operate at 7 Barg. With this information, we can calculate the required discharge head of the fire pump using hazen-williams equation. For more complex fire water grid networks a computer software is needed for hydraulic calculation. 

As a wild guess, let's assume that the friction loss from the fire pump to the furthest point of the grid should not exceed 1 Barg (assuming the same elevation). Thus, the fire pump discharge head shall be at least 8 Barg. With another assumption of 0 suction pressure, the required differential pressure is 8 Barg when the fire pump is flowing 7,570 lpm. 

Per NFPA 20, the fire pumps are able to run from 0 to 150% of its rated capacity.

Considering a future expansion of at least 20% increase in fire water demand, we need at leat 9,084 lpm @ 8 Bar. Therefore, solving for the rated capacity, the fire pump shall be 9084  lpm / 1.5  = 6,056 lpm

Based on NFPA 20 the nearest capacity that is higher than 6,056 lpm is 7,570 lpm. Therefore, the rated capacity we choose is 7,570 lpm. To estimate the differential pressure at this rated capacity, let's take the performance limits of NFPA 20. Whereas, at 150% flow the differential head shall not be less than 65% of the rated differential pressure. 

If our estimated differential pressure at 150% flow is 8 Bar, the rated differential pressure is 8 Bar / 0.65

= 12.3 Bar. This value shall be confirmed once the fire pump vendor catalog with performance curve is available.

Source of Firewater

I expect now that you know the minimum required amount of firewater. We have to find where to get it. 

- Is there a nearby water source like sea, river, or pond?

- Is the utility water, supplied by the utility company is reliable?

- Can I get water from underground water wells?

The firewater could be taken from the nearby body of water; sea, river, or pond. If not, then we have to store the firewater that will be used only for fire fighting. The most common way of storing the firewater is by storage tanks. 

What should be the capacity of your fire water storage tank? It depends on the expected fire hazards and fire fighting. Actual fire can last for days or it can be extinguished within 30minutes. Therefore, it is best to be guided with local regulations or international standards when deciding for the capacity of the storage tanks. Some industrials plants have a minimum off 1.5hours storage capacity sufficient for continuous fire fighting the largest demand. In refineries and bulk terminals, the fire water storage tanks ranges from 4hours to 6 hours. 

How Much Water Do I Need - Firewater Demand

I remember the time when I was in my primary school. I think I was 11 or 12 years old when our dirty kitchen caught on fire. I was cooking our rice in the earthen jar/pot in our dirty kitchen, which I use dried woods, coconut shell, and dried coconut leaves. At that time I was using coconut shell because it produces high intensity fire, jet fire like effect. By experience, coconut shell will speed up the cooking time. 

Our dirty kitchen is about a meter and a half wide. About 400 mm above the fire hole is used to dry the woods, coconut leaves, and the rib of the coconut leaves. Because of the jet fire effect of the coconut shell some of the dried coconut leaves caught on fire, but not flaming. The fire is small and manageable. Only a few pieces of leaves are burning, but just a smoke. I need water. I went inside our house to get a cup of water...I know that fire is small that a cup of water is enough. My elder sister saw me in a hurry with a cup of water in my hand. "What's that for" she asked. "Our dirty kitchen is burning" I said. Then she run to see and both of us are in shock...the flame is huge and it almost the entire dried leaves above the pot of rice. My sister went inside back in our house and asked the help of my elder brother to fight the fire. My brother used a pail of water and dump it on to the flaming fire and he get another pail of water to extinguish the rest of the fire. This is my true experience if fire fighting and it happened when I was a kid.

Based on that experienced I learned that fire could spread faster than my action. Also, the amount of water, a cup of water or two pails of water. 

Several codes and standards are used to estimate the minimum amount of firewater required for firefighting. The codes and standards will provide the application rate of firewater and the discharge duration. 

Now that you know how much water is needed. Where do we get the water? That would be in another post.

Paano Gumamit ng Pipenet

Ako ay susulat ng mga panuntunan sa paggamit ng Pipenet. Bakit ko ito nilalathala sa wikang tagalog? Kasi mahal ko ang sarili kong wika.

1. Panimula
 Ang panuntunan na ito ay aking ginawa upang ang mga baguhan sa paggamit ng Pipenet ay may magamit na reperensya upang gamiting gabay sa pagkalkula ng tamang taba ng tubo, tamang dami ng tubig, at kailangang lakas ng tulak ng tubig.


2. Sakop
Ang sakop ng panuntunan na ito ay ang mga sistemang pamproteksyon sa apoy gamit ang tubig. Ang pagbigay ng tamang taba ng tubo, tamang dami ng tubig, at kailangang lakas ng tulak ng tubig.


3. Kahulugan
Ang mga sumusunod ay mga kahulugan ng mga salitang ginamit sa panuntunan na ito:





4. Larawang Panuntunan



5. Mga Kailangan

Ang mga sumusunod ay kailangan bago simulan ang paggawa ng modelo sa Pipenet.
 

FIRE WATER SYSTEM - FIRE PUMP

Fire Pump is the heart of fire water system. The fire pump delivers the necessary amount of water for fire fighting. I may not be able to explain in layman's term the fire pump system but I will be giving links for more information. I believe fire pump manufacturers and vendors are the best source of knowledge in fire pump system. NFPA 20 is the most common code/standard used by engineers and fire protection system designers. 

Below are the links of fire pump vendor's I am familiar with:

http://www.peerlesspump.com/fire_pumps.aspx
http://www.peerlessxnet.com/documents/B-1540.pdf
http://www.tppump.com/media/literature/Brochures%20and%20Technical%20Data/Fire%20Protection/Patterson/Patterson%20Fire%20Pump%20Brochure.pdf
http://completewatersystems.com/brand/a-c-fire-pump/literature/
http://www.aurorapump.com/EngineeredApplications_FireProtection.aspx
http://www.firesafetysearch.com/products/fire-pumps/
 http://www.nijhuis.com/EngineeredSearchResults.aspx#ProductType=Fire+Pumps+%26+Systems|isAccessory=true

COMMON FIRE PROTECTION SYSTEMS

When you go out malling, shopping, or checking-in hotels, wherever you go you'll find a cylindrical red object hanging on the wall, or sometimes you'll see white or red hose near exit doors. Those are fire extinguisher and fire hose installed for fire fighting use. But we are not limited to portable systems. When you look at the ceiling you will find a small object like inverted umbrella with small piece of colored, sometimes red, object.

If you still remember the movie Hollow man there is a scene where somebody shoot an object to let the water come out to see the figure of hollow man. That object is what we call sprinkler. On other luxurious hotels or buildings, these sprinklers are hidden or concealed.

There are many fire protection systems that are installed today to protect people and properties.
As we go along with this blog we will discuss each systems in detail to the best I can. As of now, the following fire protection systems are, what I know, commonly used.

Residential Areas:
A. Sprinkler Systems - in US they have a regulation to provide sprinkler system for residential houses. Of course it depends on how big your house is or how many person and hazard are present.

(upload.wikimedia.org)

(www.reevesplumbing.com)

B. Fire Hydrants - these are located along the roads and should not be blocked such as by parking your car.

www.sccfd.org/hydrants_bluedots.html)

C. Portable Fire Extinguishers - it is recommendable to provide fire extinguishers in our home near our kitchen, bedrooms and living room. And every member of the family should experience and should be trained to operate portable fire extinguishers. Later on I will discuss my recommended fire safety program for our home.

(www.adelaidebackpackersinn.net.au)

(www.utsystem.edu)

D. others - to be added later

Buildings:
A. Sprinkler systems
B. Fire hydrants - located outside the building
C. Portable Fire Extinguishers
D. Dry Chemical Automatic fire extinguishing system -for the building's kitchen rooms
E. Clean Agent Systems - for computer rooms
F. CO2 Fire Extinguishing system - applicable for computer rooms
G. many more- to be added later

Industrial Plants:
A. Industrial plants include small buildings such as control building, electrical building, instrument building, and administration building. May be some large industrial plants will have sleeping quarters and separate building for canteen and laboratory. Therefore, the fire protection system will always depend on the hazard inside the building.

B. Outdoor Hydrants are provided and sometimes with fire hose cabinets that store different portable devices; fire hoses, hose nozzle, etc.

C. Foam Systems are provided if the plant is processing hydrocarbons such as diesel oils, gasoline, etc.

D. Fire Trucks - since most of the industrial plants are located far from municipal fire department the plant should have its own fire trucks and emergency vehicles. But sometimes small industrial plants are located on what government call "Industrial Areas" in which there is a fire department intended for Industrial Areas.

E. Other systems - as of now, I cannot think of systems that I missed. Later, I will add if I find something is missing and worth mentioning.

WHAT IS FIRE?

Let us check the definition from the Webster’s New World College Dictionary on Power CD.




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Other books define FIRE as chemical reaction involving rapid oxidation (combustion) of a fuel. (Guidelines for Fire Protection in Chemical Petrochemical, and Hydrocarbon Processing Facilities,Appendix B, Understanding Fires). This definition can be understood by engineers, scientists, and may be some individual. Let me define in simple term, as what they call "in layman's term". Fire is the reaction when we apply enough heat to burnable material with the presence of oxygen. With the help of Webster’s New World College Dictionary on Power CD let us look for the definition of heat and oxygen.












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in a larger window)


I hope that those definitions of Heat and Oxygen will give you enough idea. Anyway, oxygen is abundant in Air. The air we breathe contains 21 % of oxygen. Because air is present everywhere we can always assume that any burnable materials is in contact or will easily be in contact with oxygen. If you are thinking what are those burnable materials I will give you several examples.


Let me introduce first the National Fire Protection Association (NFPA). This association is composed of several engineers and specialist in fire protection. They published NFPA 10, Standard for Portable Fire Extinguishers. This standard classify the different type of burnable materials into what kind of fire it will create




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I think now it is clear to readers that most of the things around us burn: our clothes, any products made of wood, plastic materials, products made of oil such as gasoline and lubricants, even metals burn. Therefore, there is a great risks on those burnable materials if we will not provide fire protection systems.