Let's start a this thread naman about fluids. Anybody who wants to define what a fluid is? :rolleyes:

A fluid is defined as a substance that continually deforms (flows) under an applied shear stress regardless of how small the applied stress. All liquids and all gases are fluids. Fluids are a subset of the phases of matter and include liquids, gases, plasmas and, to some extent, plastic solids

:panilag: :panilag: :panilag:

Nice. So we continue. Ano ang difference naman sang liquid vs gas even though they are both fluids?

One of the difference between gases and liquids is that molecules in the liquid state interact with each other through intermolecular forces. These forces hold liquid molecules together. When molecules are in the gas state, they don't interact much. This is why liquids keep their volume but gases do not. Gas molecules aren't held together strongly, so they can spread out, filling as much space as they can.


:panilag: :panilag: :panilag:

Perfect! Let me simplify. Liquids are non-compressible. Gasses are compressible. And the best way to compress a gas... is to turn it to liquid! :D :D :D

Bwas naman kay manugpuli na ko. Let's discuss liquids first. Hydraulics. Let's discuss gasses later on. Pneumatics. :P

:panilag: :panilag: :panilag:


pnuematics?...piping design of compresed gases?... :naughty: :D

pwede! Ti, unahon ta pneumatics?

ok ah... total damu pa ko ginakuti... maasa lang ko mga tugda anay ...... :D

Duman ko gusto mo gid, ikaw bala mong. Balik ta sa hydraulics anay para maintindihan ang physics. Mas hapos ang liquid kay makita. Mas budlay and gas kay invisible. First discussion is pressure. Let us imagine a glass of water. May pressure nga ma-build up sa walls and bottom sang glass. What causes this? ;)

presure due to hiehgt of the liquid.... ang formla is....


P = rho * G * h

Rho = desity of liquid
G = gravity
h = height

pressure varies as the height changes...as the height of the liquid increases, the pressure also increases.....

but

kung oen air ang istoryahan, reverse ini sya.... as the height increases, the pressure of air decreases.... :thumb:

Why is this so? What is the cause?

.... as the height gies hogher, the density of air theoritically goes thinner..... but for the purpose of computation we had used 0.075 lb/cubic ft...... what causes this?... dali lang.. maminsar ko anay.. :naughty: :naughty: :naughty: :naughty:

nong raymie..... laptahun ko ang problems kay konectado sa iban nga subjects......

suguran ko sa fluid mechanics....



Problem#1

I had just completed a 5400 square meters building with roof inclination of 8deg. during commissioning of the building, I wanted to simulate a huge rainfall to check the quality of roofing installed....Assuming the data from PAGASA is TRUE that the largest rainfall for the past 10 years is 10mm in 5 mins. Questions:

1. What is the total flow (in gpm) of water do i need to have?
2. Assumming that i will distribute the water to 4 fire water nozzles, how many 3" dia nozzle do i need?...

Please state assumptions, no definite answer as assumptions varies based on standards and market sizes...

corrected.. i spotted a typo error :D

Since you are a conservative designer, you would want to max out the specs. So let's say we get the highest rainfall number and add another 10%. Total volume of water will then be:

Vol = Area X Height = (5400) (0.01) -> in m^3

Adjusted Vol = 1.1 Vol = (1.1) (54) ~ 60m^3

All this water will be collected in 5min so,

Q = 60/5 = 12m^3/min ikaw na lang convert sa GPM


Since i-distribute mo ini tanan into X nozzles, that would be (12m^3/min / X) flow per nozzle. Ang pamangkot mo is pila ka nozzles ang gamiton mo. So you need to know how much pressure build up your system can sustain. Based on the pressure available, and using Bernoulli's equation (Energy in = Energy out), you convert all your pressure head into velocity head for your nozzles. You will then get the max flow rate per nozzle. Simple division will follow to divide the total needed flow by your nozzle available flow.

Ang kwestyon, diin halin ang pressure? :P

hmmm......

correct!!!! :thumb: :thumb: :thumb: :thumb:

pero... kung diin halin ang pressure is next sa mga series of problems.... ;) :D

hint: to get the flow, may standard nga flow designers use to compute the flow of water... that is 6-8 m/sec.... means, the velocity capacity of pipe/nozzle averages in that range.... :D

initial computation is correct, pero daw duda ako sa 10mm in 5 min nga assumption kay daw kadaku gid ini :D :D :D

Data speaks. "Duda" is feelings. Engineer? :lol:

kay ang 10mm in 5 min came out sa isa ka data sang PAGASA last year.... amu na kuno ang pinakadaku nga rainfall for the past 10 or 50 years i think....

on the other handm since fluids ang topic....if you recall the typhoon melenyo nung 2006.... melenyo can be considered as the "rainfall of the century" kung basehan sa cavite-laguna area.... kay ang rise of water nya only happens once in every 100 years ....this was brought about by the hydrology study we had middle of last year... :thumb:


ipapilit ko diri bwas ang computation ko ah.... naga himu pa ko follow up problems.... :D :smoke

Daw upod to ya guro sa high tide To^ amo nga taas gid ang baha.

posible nga upod sa high tide pero ang basehan lang naman namun ang creek sa likod sang OSPI, the creek also had restrictions sang mga basura before passing through laguna de bay amu man na nga nagtaas ang water level sa area...

that is also the reason why we went a little conservative and leveled the "new admin" (tani galing wala madayun) about 0.2m higher than the old building..... so, if my information is right nga may expansion ang previous employeer ko, the new building and structures should be leveled about 0.2m higher than the existing building... medyo costly.... pero otherwise it may have the risk of flooding inside the mfg floor area...

well... my thoughts... :lol:

Ang daku mo gid nga problema kay ulan ang gusto mo i-simulate. Ti kinanglan mo gid damo-damo nga nozzles! :lol: :lol: :lol:

ti indi ma perfect ang ulan pero one thing nga matesting dira ang integrity sang mga water spouts kag storm drains :thumb:

Balik ta sa basics ha.

1. Pressure is caused by the weight of the fluid in open/exposed containers. In closed containers, it is due to gravity ++.

example: Atmospheric pressure = 14.7psi because of the weight of the air around us.

2. Pressure acts perpendicular to any surface it acts upon. This is because fluids are not able resist shear stresses

3. Pressure causes people to rebel against their bosses...

Hmmm daw amo ni ang pina ka common nga pressure subong :naughty: :naughty: :naughty:

talking of boses.... off topic anay ako...



read on........






Every boss wants employees who do their jobs well. But even among highly competent employees, there are distinctions. Here are 10 tips for making sure you're on the boss's A-list:

1. Communicate, communicate, communicate. Especially at the beginning of your relationship -- that is, when either you or the boss is new to the job -- err on the side of giving your boss too much information and asking too many questions.
"There's no such thing as a dumb question," says Marianne Adoradio, a Silicon Valley recruiter and career counselor. "Look at it as information gathering."
Don't keep up the constant stream of communication unless your boss likes it, though. It's best to ask directly whether you're giving the boss enough information or too much.

2. Acknowledge what the boss says. Bosses appreciate "responsive listening," says John Farner, principal of Russell Employee Management Consulting. When your boss asks you to do something or suggests ways for you to improve your work, let her know you heard.

3. Collaborate. When your boss has a new idea, respond to it in a constructive way instead of throwing up roadblocks.
"Be willing to brainstorm ways to get something done," says Michael Beasley, principal of Career-Crossings and a leadership and career development coach.

4. Build relationships. You'll make your boss look good if you establish a good rapport with your department's customers, whether they're inside the company or outside. Bring back what you learn -- about ways to offer better customer service, for example -- to your boss. This is also helpful for your own career development.
"Everybody wins in the long run," Adoradio says.

5. Understand how you fit in. Is your boss detail-oriented, or someone who keeps his head in the clouds?
"The boss's personality is just incredibly important," says Norm Meshriy, a career counselor and principal of Career Insights.
Equally important is understanding what your boss wants in an employee. It may be, for example, that a boss who is detail-oriented will expect his employees to be as well. But a boss who has no time for details may actually appreciate an employee who does.

6. Learn the boss's pet peeves. If your manager has said repeatedly that she hates being interrupted first thing in the morning, don't run to her office to give her a project update when you first get in.
7. Anticipate the boss's needs. Once you have worked with your boss for a while, you should be able to guess what information he will want before approving your purchase order, for example.
If you provide it ahead of time, "that's a gold star," Farner adds.

8. Think one level up. You still need to do your own job, of course. But when managers consider who deserves a promotion, they look for people who understand the issues that their bosses face.

9. Open yourself to new ways of doing things. When your boss comes to you with a new idea, don't simply dismiss it. If you don't think it will work, offer to discuss it further in "a mature, responsible, adult-like way," Beasley says.

10. Be engaged in your work. Arguing with your boss over every request is not a good strategy, but neither is simply shrugging your shoulders and agreeing with everything your boss says. "The manager would like to see an engaged individual," Beasley says. That means both showing enthusiasm for your work and speaking up when you see room for improvement.

mig comment lang ko. Correct me if im wrong but as internationally accepted and to prevent the errosion factor as will as the fouling factor sang pipe, the maximum linear velocity must not be over 10 ft/second or 3 meters per second. piping system whether it is a free flow, pressurized or a forced main shall are designed upto 2 meters per second only. That will always be the basis sang pipe sizing sa mga pump stations.

will try to give you a reference meg... but kung water, ang ginausar namun is 7m/sec.... and it will go slower kung naga change ang viscousity sang fluid.. :)

i stand corrected mig.... insakto ka that its ft/sec......




so the water flow should be 6-8 FT/SECOND and NOT meters/sec nga ginhambal ko....


ref C.714 7th Edition, Piping Handook by Mohinder Nayyar


:thumb: