Tell us more about the fire sprinkler. What are its specs?

specs is A-12y

please elaborate

Hello vimal482,

Welcome, and you are allowed to type longer sentences you know!

I need some details on what kind of hydrocarbon, quantities, size of installation and size of tanks please? Can you tell me if possible what country you are in please?

Take care..................

hi

i m working with RIL in india

tank dia is 50.00 mtr,having gesoline .

pls reply.

thanks.

Hello vimal482,

I will do my best to help and I am sure others will also. The problem I have it why you want to know?

If you were fitting a sprinkler to a oil depot for instance there is all kinds of regulations and rules you should abide by. Even if this site does not exist, it is pretty much a known sum to be able to work out the number of tanks of a certain size and then the supplies, pipe type and sizes and actual sprinkler type can be thought about.

Are you an Engineer or fire prevention expert? What is your capacity in this project.

You see, you must either be on a site already built and needing maintenance or, know the general design if this is a new installation on a new plant. The fact you know the sprinkler type, means that you already know the pipe size, and any sub-pipe size to feed more than one tank or lot of sprinklers.

You cannot just go out and buy some sprinklers for a new depot without knowing all the above details.

It is like buying your four wheel drive, only to realise it will not fit in your garage?

There was a similar question a few weeks back on gas installation fire prevention on an oil rig. It seem odd that you may be hired to do a job but are not qualified to do it? Can you alley my fears?

No insult intended but, a little more cooperation and discussion has to happen before any advice can be given. And, you should not rely on the advice entirely, as we have no idea of the size, and its proximity to other factories and or residential dwellings?

Take care and please discuss this with us and do not be worried about talking about it to the local council, and planning office. They will have to give the design the thumbs up anyway.

Hello vimal482,

If you cal tell me the final pipe size I can tell you the flow rate. But you should bear in mind in a Hydrocarbon installation CO" and other methods and mixers should be used

line size 4"

Hello Guest,

This is part of a extremely informative site, which includes a lot of examples and explanations of how to figure out FLOW RATE in most situations.

However, this is only WATER FLOW RATE.

If you are dealing with Hydro-Carbon/Petro-Chemical FIRE PROVENTION, other means should be taken into account, like CO2, powder etc.

In a Petro-Chemical situation, water can make the fire worse and, is really only a 'cooling agent'.

This is the site address: http://www.lightmypump.com/tutorial3.htm

PLEASE READ ALL THE SITE INFORMATION INCLUDING ANY LINKS. Thank you.

Please get back to me when you have more info' on the site. I do not believe you are dealing with a 'real' situation and would be grateful if you could be honest enough to explain whether this is just a ref' to a college course?

CENTRIFUGAL PUMP SYSTEM TUTORIAL

previous

What is total head

Total head and flow are the main criteria that are used to compare one pump with another or to select a centrifugal pump for an application. Total head is related to the discharge pressure of the pump. Why can't we just use discharge pressure? Pressure is a familiar concept, we are familiar with it in our daily lives. For example, fire extinguishers are pressurized at 60 psig (413 kPa), we put 35 psig (241 kPa) air pressure in our bicycle and car tires.For good reasons, pump manufacturers do not use discharge pressure as a criteria for pump selection. One of the reasons is that they do not know how you will use the pump. They do not know what flow rate you require and the flow rate of a centrifugal pump is not fixed. The discharge pressure depends on the pressure available on the suction side of the pump. If the source of water for the pump is below or above the pump suction, for the same flow rate you will get a different discharge pressure. Therefore to eliminate this problem, it is preferable to use the difference in pressure between the inlet and outlet of the pump.

The manufacturers have taken this a step further, the amount of pressure that a pump can produce will depend on the density of the fluid, for a salt water solution which is denser than pure water, the pressure will be higher for the same flow rate. Once again, the manufacturer doesn't know what type of fluid is in your system, so that a criteria that does not depend on density is very useful. There is such a criteria and it is called TOTAL HEAD, and it is defined as the difference in head between the inlet and outlet of the pump.

You can measure the discharge head by attaching a tube to the discharge side of the pump and measuring the height of the liquid in the tube with respect to the suction of the pump. The tube will have to be quite high for a typical domestic pump. If the discharge pressure is 40 psi the tube would have to be 92 feet high. This is not a practical method but it helps explain how head relates to total head and how head relates to pressure. You do the same to measure the suction head. The difference between the two is the total head of the pump.

Figure 25

The fluid in the measuring tube of the discharge or suction side of the pump will rise to the same height for all fluids regardless of the density. This is a rather astonishing statement, here's why. The pump doesn't know anything about head, head is a concept we use to make our life easier. The pump produces pressure and the difference in pressure across the pump is the amount of pressure energy available to the system. If the fluid is dense, such as a salt solution for example, more pressure will be produced at the pump discharge than if the fluid were pure water. Compare two tanks with the same cylindrical shape, the same volume and liquid level, the tank with the denser fluid will have a higher pressure at the bottom. But the static head of the fluid surface with respect to the bottom is the same. Total head behaves the same way as static head, even if the fluid is denser the total head as compared to a less dense fluid such as pure water will be the same. This is a surprising fact, see this experiment on video that shows this idea in action.

For these reasons the pump manufacturers have chosen total head as the main parameter that describes the pump's available energy.

What is the relationship between head and total head?

Total head is the height that the liquid is raised to at the discharge side of the pump less the height that it is raised to at the suction side (see Figure 25). Why less the height at the suction side? Because we want the energy contribution of the pump only and not the energy that is supplied to it.

What is the unit of head? First let's deal with the unit of energy. Energy can be expressed in foot-pounds which is the amount of force required to lift an object up multiplied by the vertical distance. A good example is weight lifting. If you lift 100 pounds (445 Newtons) up 6 feet (1.83 m), the energy required is 6 x 100= 600 ft-lbf (814 N-m).

Head is defined as energy divided by the weight of the object displaced. For the weight lifter, the energy divided by the weight displaced is 6 x 100 / 100= 6 feet (1.83 m), so the amount of energy per pound of dumbbell that the weight lifter needs to provide is 6 feet. This is not terribly useful to know for a weight lifter but we will see how very useful it is for displacing fluids.

Figure 26

You may be interested to know that 324 foot-pounds of energy is equivalent to 1 calorie. This means that our weight lifter spends 600/324 = 1.8 calories each time he lifts that weight up 6 feet, not much is it.

The following figure shows how much energy is required to displace vertically one gallon of water.

Figure 27

This next figure shows how much head is required to do the same job.

Figure 28

If we use energy to describe how much work the pump needs to do to displace a volume of liquid we need to know the weight. If we use head, we only need to know the vertical distance of movement. This is very useful for fluids because pumping is a continuous process, usually when you pump you leave the pump turned on, you don't start and stop the pump for every pound of fluid displaced. We are mainly interested in establishing a continuous flow rate.

The other very useful aspect of using head is that the elevation difference or static head can be used as one part of the value of total head, the other part being friction head as shown in this next figure.

How much static head is required to pump water up from the ground floor to the second floor, or 15 feet up? Remember that you must also take into consideration the level of the water in the suction tank. If the water level is 10 feet below the pump suction connection then the static head will be 10 + 15 = 25 feet. Therefore the total head will have to be at least 25 feet plus the friction head loss of the fluid moving through the pipes.

Figure 29

How to determine friction head

Friction head is the amount of energy loss due to friction of the fluid moving through pipes and fittings. It takes a force to move the fluid against friction, in the same way that a force is required to lift a weight. The force is exerted in the same direction as the moving liquid and energy is expended. In the same way that head was calculated to lift a certain weight, the friction head is calculated with the force required to overcome friction times the displacement (pipe length) divided by the weight of fluid displaced. These calculations have been done for us and you can find the values for friction head loss in Table 1 for different pipe sizes and flow rates.

Table 1

Download a printer friendly version (Imperial units or metric units).

Table 1 gives the flow rate and the friction head loss for water being moved through a pipe at a typical velocity of 10 ft /s. I have chosen 10 ft/s as a target velocity because it is not too large which would create allot of friction and not too small which would slow things down. If the velocity is less, then the friction loss will be less and if the velocity is higher the loss will be greater than is shown in Table 1. For the suction side of the pump, it is desirable to be more conservative and size pipes for a lower velocity, for example between 4 and 7 feet/second. This is why you normally see a bigger pipe size on the suction side of the pump than on the discharge. A rule of thumb is to make the suction pipe the same size or one size larger than the suction connection.

Why bother with velocity, isn't flow rate enough information to describe fluid movement through a system. It depends how complicated your system is, if the discharge pipe has a constant diameter then the velocity though out will be the same. Then if you know the flow rate, based on the friction loss tables, you can calculate the friction loss with the flow rate only. If the discharge pipe diameter changes then the velocity will change for the same flow rate and a higher or lower velocity means a higher or lower friction loss in that portion of the system.You will then have to use the velocity to calculate the friction head loss in this part of the pipe. You can find a velocity calculator here http://www.lightmypump.com/applets.htm#applets4

If you would like to see a chart of flow rates for 5 ft/s (imperial or metric) and 15 ft/s (imperial or metric) download them here.

For those of you who would like to do your own velocity calculations, you can download the formulas and a sample calculation here.

Those who would like to do pipe friction calculations can download an example here.

A calculator for pipe friction loss is available here ( http://www.lightmypump.com/applets.htm#applets13) and for fittings friction loss here( http://www.lightmypump.com/applets.htm#applets15).

Take care.................................

Please refer to NFPA standards:

http://www.nfpa.org/catalog/search.asp?query=nfpa+30+&cookie_test=1

Simply said...I really think you're kind in the wrong place doing the wrong job man.

The guru is trying to give a helping hand and your answers simply say that you don't even know what you're doing or why you're doing it for.

Please consider your qualifications before you engage in serious work, people get hurt everyday you know...