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UPC Appendix A 1

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beameupscotty

Civil/Environmental
Aug 7, 2003
17
I have a couple "technique" questions for sizing private residential multiplex townhouses.

1. When counting pressure losses from the city's main:

-What's a typical loss from the tap to the meter (1-1/2")?
-Is 3 psi reasonable for loss through the meter?
-For a run of 350 LF with one horizontal bend (2-45d or a 90d), what's a reasonable assumption of bend losses? (pipe is 1-1/2" PVC sched40)
-Do I count all bends through the plumbing in the house and add to my losses.
-Do I use the city's average pressure or find out the lowest pressure? (city PW gave me average)

2. When counting fixture units:

-Is a dishwasher a seperate unit from the sink it connects with?

3. Where can I find a chart like A-4 or A-5 for PVC? I have the '94 book with some pages taken from the 2004 version.

Thank you to anyone who has the time and desire to help me with any or all of my questions.
 
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I can help with a few.

1. You should consult the manufacturer's literature about the pressure loss of the meter. Since there are a few different types of meters, it would be difficult to give a catch all for the pressure loss.

2. When determining the pressure loss, you need to know what your flow is going to be. Without a flow rate, the probable pressure drop is not possible to calculate.

3. If you have a lot of bends, my rule of thumb is 50% of equivalent length for fittings.

4. Whether to use the average pressure or lowest pressure depends on what the pressure of your fixture with highest pressure requirement and how close that pressure is to what the average is. Generally, I try to get the lowest for safety sake. You also should find out when that average is taken. Is it taken during a period of little use. If the water is on a tank, is the pressure taken when the tank is full or empty? You need to know what other users are on the water supply piping. You should also try to determine what if any future expansion will take place which will reduce the pressure available at a later date.

5. When figuring fixtures, a dishwasher (if it is residential) should not increase the sink's fixture count.

I am not sure what a A-4 or -5 is since I predominantly use the IPC. I will look it up and see what it is.

Hope this helps.
 
A little clarification on my previous comments.

5. A dishwasher is considered separate from the sink. They have a similar fixture unit count. It would be safe to assume that you would only use one at a time. I guess it is possible to have the sink draining at the same time, but it is highly unlikely. If you desire, you can add the two values.

I found the A-4,-5. You can use the chart for copper tubing for PVC. They have very similar friction characteristics (at least for new piping).
 
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