How Much Water Required For 5hp Steam (Piston) Engine ?

<...Approx water quantity to design its boiler....>

What is the operating pressure of the boiler?

Steam power is nothing to play with. A water heater has several safety features for a good reason. Even a small steam engine can quickly turn into a bomb. IMHO this is a case where if you have to ask, you're not qualified to do this on your own.

i gess you where born with this nolige & did'nt have to ask any one

It takes one pound of water to make one pound of steam.

The rate of water consumption depends on the how fast you boil off the water, which has everything to do with the pressure in the boiler. Higher pressures, higher boiling point.

The pressure your going to run this boiler at depends on how much torque is required to spin that wheel at 2000 rpm.

It is important to have sufficient feedwater for the boiler at all times, especially if you are running at pressures above atmospheric. And, of course, the feedwater pump must develop greater pressures greater than boiler pressure to force the feed water into the boiler.

With boilers running at higher pressures it is very important to maintain design water levels in the boiler because boiling water is explosive in nature. I wouldn't run any kind of boiler, hobby or otherwise, without a low water cut-off that shuts off the fuel supply when the boiler water level drops below the design water level.

And, by the way, install a safety valve to limit the maximum boiler pressure and make sure it discharges somewhere other than in your face or upon passerby'ers.

For historic reasons, a "boiler horsepower" is 34,075 Btu/h, which at an approximate latent heat of 1000 Btu/lb equates to boiling about 34 lb/hr. So 5 hp ≈ 170 lb/hr.

Then it depends on whether you are just blowing the steam off versus condensing and recirculating it.

For a mobile application, the minimum amount of water provides the least stored energy in case of accident, so a flash boiler is suggested. The amount of superheating and working pressure and temperature call for differing amounts of steam at a given power output. I think the suggestion that you need more design work before deciding on the details of construction is very valid, as in "back to the drawing board."

There are clubs of usually composed of "old timers" who have significant experience in steam engines. I sure would connect with them, and I think they publish a magazine.

There is also Lindsay Publications which every engineer should have at least one book from.

I regret my text book responses, but steam can be dangerous.

Years ago in another life when I lived on the coast I started assembling plans to build a steam powered skiff. It didn't get off the ground, but someday I could revisit the idea!