QOD for 2/26/2006 Plumbing

Inspection Education Topics Inspection Question of the Week
1

Hi to all,

Here’s todays question

Regards

Gerry

2

How about a home with one or more teenagers?

3

Joe, although not specifically addressed in either IRC or UPC, I believe that should be a feature of future code revisions.

I also think that the shower should automatically cut off after delivering 20 gallons of hot for the same reason :wink:

Regards

Gerry

4

Hi to all,

The correct answer to this is **1 inch

**Whilst it is a code issue (IRC 2903.7 & UPC 610.1), it is really a common sense issue, if a home has multiple bathrooms it probably also has higher occupancy and as such would require a larger supply to maintain functional flow under load.

Regards

Gerry

5

Both the IRC and the UPC have good water sizing tables to help explain this. If I could find them I would post them.

Good question Gerry.

6

Maybe a dumb question.

Does it vary with where your water is coming from? Say, such as a water system that has to pump uphill? Would you perhaps need to go to a smaller diameter to maintain the same level of water pressure as in a situation where the water system is on a level?

7

If are going uphill the pressure will naturally drop no matter the pipe size. Pressure and volume are different and easily confused. Now the functional flow rate is dependent on pipe size and water pressure (there is more to it but it is boring). So larger pipe size will help with lower pressure, somewhat. If you reduce the pipe size going up hill the pressure will stay the same but you will reduce flow.

8

Thank you Brian. That was actually very helpful. I appreciate the time you took to answer my question.

9

My pleasure, I have to increase my useful info/spam ratio to a measurable amount.

10

Brian Wrote:
If are going uphill the pressure will naturally drop no matter the pipe size. Pressure and volume are different and easily confused. Now the functional flow rate is dependent on pipe size and water pressure (there is more to it but it is boring). So larger pipe size will help with lower pressure, somewhat. If you reduce the pipe size going up hill the pressure will stay the same but you will reduce flow.

Brian & Wendy,

  1. As elevation increases by 2.31 feet, pressure drops 1psi.

  2. Increasing pipe diameter decreases pressure drop (losses) due to friction.

  3. Decreasing pipe diameter serves to increase flow velocity in feet/minute, but increases the friction losses thereby decreasing guage (sensible) pressure.

  4. The horsepower required to lift water h distance is = GPM X h (in feet)/3960. This neglects efficiency loss.

tg

11

Tim.

  1. Correct

  2. Pressure is pressure, now if you want to go all engineer on me and speak to the functional flow or flow coeffecient of the system or components of the system, my question is why? But be my guest have at it.

  3. Durring flow conditions, what of it?

  4. Ok then I’ll neglect it too.

12

Hi to all,

I am so glad we have a couple of scientists around, because tomorrow my answer is going to include Pi, I suspect a few members are going to be wanting some help :mrgreen:

Regards

Gerry

13

holly crap i got it right…i mean, i knew that.:roll: :wink: :cool:

14

Very funny Gerry. But I do love Pi never met a Pi i didn’t like, steak and kidney and sheppards Pi included. Got the dunlap to prove it.:wink:

15

Tourtier’ PI works for me.

Marcel :wink: