Pressure from garden hose

[JASON8102]

If I have a cylinder made of S.S. of some "T" (thickness) and this cyclinder has only one hook up for a garden hose to be attached to it, and no outlet for over flow to escape. What is the formula I would use to determine pressure inside the tank created from garden hose. Lets say the garden hose creates 3psi. (I'm not sure of the pressure created by one.)

 

[Pulpboy]

Sounds a little too much like a homework question and not like real work.

 

[LuizSouza]

DOSEMBRO is pretty quite right, at least, with so few infomatoons.

 

[JASON8102]

no homework at all. I design confectionary equipment for a company. There was an electrician here saying that I couldn't hook up a garden hose to a choc. melter. The choc. melter has a jacketed tank and of course needs to be filled. He was trying to tell me the pressure would be to great because the air in the tank would have no where to go. The tank itself is 11ga. S.S. I told him that he was right to a point. I believe the pressure would build up to a certain point where it would cause back pressure against the inlet where the garden hose is hooked up and would just stop water flow. No? I'm not hooking it up to a firehydrant.

 

[rwelk]

Maybe I'm just not reading this right, but are you simply filling up the tank?

If so, is it too difficult to put an escape valve on top just to be sure? Either way, the calculation does not seem to be too difficult. Constant temp, and amount of air, with a change in volume and pressure.

I'm a matls guy, but it seems like if you fill the tank from empty to half full the pressure will double. The water should fill the tank until the pressure inside equals the pressure of the hose.

I hope this helps, but i think i might have misread your question.

 

[hacksaw]

A couple of issues:

Use of a garden hose fitting seems a bit out of place in a food grade manufacturing application.

Having said, it is not clear how you intend a single fitting on the jacket to accomodate filling,draining, and venting operations.

The jacket pressure in a valve free connection to a water supply will not exceed the line pressure.

 

[jte]

Jason8102-

If the tank has to be filled with water, but there is not means of venting the air, then the design is poor. If it is small enough, I'd suggest turning the tank such that the filling opening is up and pouring the water in and letting the air vent out.

What worries me is your assumption that the hose will put out 3 psi. That is more than an order of magnitude off from typical US residential plumbing. Depending on your system, you should expect to see between 40 and 80 psi. If you leave the air in the tank, you, as you suspected, will have a mix of air and water both at the hose pressure of 40 to 80 psi. Now, with a large volume of air at 80 psi, depending on the design of the tank, you may have a hazardous situation. There's a reason we don't usually do pneumatic tests.

jt

 

[a31ford]

Did anyone actually READ the original post.... or is everyone simply wanting to express their views on the tank >?

Jason, I too thought this was a good place to "spark thought" but I see, as you have, that they are not really reading...


Regards,
Greg,

Called "Mr. Fusion" by the Locals

 

[finman]

I read the original post and the suplimentary one and I'm still puzzled, I feel that like the rest of the gang there is something a miss here.

I too have worked in the confectionary industry and designed Jacketted tanks, all of our units were steam filled and sensibly had an inlet and outlet for the steam jacket.

In my experience the question does not arise, so please elucidate and fill in the details.

 

[jte]

Jason and Greg-

Sorry, perhaps I wasn't clear in my first reply. To directly answer the question, the pressure in the cylinder will equalize to the supply pressure. The formula would be: Pcylinder=Psupply. The air will simply be compressed by the incoming water until the pressures are equal.

jt

 

[saxon]

Jason8102, My rule is "No garden hoses in industrial or commercial applications". They have a nasty tendency to leak and are easily damaged in handling and is a bad habit to let get started.

Now, in regards to the question regarding pressure. The concept is "system equilibria". Such that, the jacket pressure will equal the system pressure when equilibria is reached. If three psi, jacket pressure will be three psi. As for the air in the jacket, this will compress until it reaches the system pressure. For a water service this seems a little low, most potable sources run at range from 50 to 75 psi.

Hope this helps.
saxon

 

[JohnGP]

Jason8102

As you believed and others have pointed out, maximum pressure in the tank when the water in the garden hose stops flowing will be the pressure of the water supply (unless of course there is also a heating step).

How much is too much pressure? For that you need to know the pressure capability of the tank (it needs to be designed for pressure if you are pressurising with air and water) and the pressure of the water supply. The latter is easily checked by rigging a pressure gauge to the end of your hose, but be aware of possible variation in supply pressure depending on local demand influences.

Regards,
John

 

[a31ford]

OK,

Sorry ALL !!!!

I was crude, I retract my original post, as I was incorrect in my statement.

Everyone have a Fantastic Day !

Regards,
Greg,

Called "Mr. Fusion" by the Locals