Yeehah its Chris bashing season again.
Adding to Chris's comments:
True networks are always troublesome things, and expressing demand in daily consumption is always a recipe for misunderstanding.
For example, and increase from 45 to 70 TPD sounds like an upgrade at a small plant. The nature of the increase and the existing demand profile must be known in order to predict the effect on the system.
For example while the daily demand is 45TPD, the peak hourly demand could easily be four times this if, say showers at knockoff time are a major component of the daily demand. If more showers are installed then chances are the peak demand will increase and the hydraulics may suffer accordingly. However if a second shift is added then no more showers need to be added, and the hydraulics will remain the same although the daily demand will be increased. Similarly, if the increase in daily demand is due to another cooling tower, then the effect on the system hydraulics may be negligible is the system was sized for a peak demand well in excess of the average.
Another area in networks which can cause difficulty is the concept of residual pressure/head which is the required head at the point of discharge or ownership transfer. Suppose the required residual head is 30psi and the network system loss is 10 psi. Then the required pressure at the (single) network supply node is 40psi Then assuming the peak demand increases as the daily, the new required pressure is 10 X 2.6 + 30 = 56psi.
With networks it is more important that usual to formulate any question clearly. It is essential to know or agree the peak instantaneous demand in order to size the pumps and pipes. Daily demand is of more interest from an accounting/stockholding perspective.
Cheers
Steve
-----Original Message-----
From: <a href="/group/PipingDesign/post?postID=JISVa1jJKWJ6Uj6_7N9fGi1BcBRZsvX1YHL-wsJrlXUeTkg2ZnbIGmAyw8k5e_gmZI1dq0p9UO2wEi5EDufFLY8D0qcKCg">PipingDesign@yahoogroups.com</a> [mailto:<a href="/group/PipingDesign/post?postID=JISVa1jJKWJ6Uj6_7N9fGi1BcBRZsvX1YHL-wsJrlXUeTkg2ZnbIGmAyw8k5e_gmZI1dq0p9UO2wEi5EDufFLY8D0qcKCg">PipingDesign@yahoogroups.com</a>]
On Behalf Of Christopher Wright
Sent: Tuesday, August 30, 2005 4:04 PM
To: <a href="/group/PipingDesign/post?postID=JISVa1jJKWJ6Uj6_7N9fGi1BcBRZsvX1YHL-wsJrlXUeTkg2ZnbIGmAyw8k5e_gmZI1dq0p9UO2wEi5EDufFLY8D0qcKCg">PipingDesign@yahoogroups.com</a>
Subject: Re: [PipingDesign] Potable water Piping
> If a present system is warking on 40 psi and
> fulfilling the requirement of 45 ton/day and if the requirement goes
> to 70 ton per day than what is the critaria of hydraulics of potable
> water netwark?
In general the pressure drop across a network goes as the square of the
flow rate. If you jack up the flow rate by a factor of 70/45 = 1.6 the
upstream pressure needed to get all that water through will increase by
a factor of 2.6 if you make no mods to the system. The flow velocity
(which affects associated response, like water hammer) goes up by the
1.6 factor. You can start checking the system part by part to see what
changes you need to make to withstand the new pressure and handle the
new velocity.
Christopher Wright P.E. |"They couldn't hit an elephant at
<a href="/group/PipingDesign/post?postID=wmD74Sm2Dd9zVv9seIWDr4UHpzsni2XcFVZ1DDUwjMHh_J689uWzhg57xO-xgnSIOtzBavgLmLc6">chrisw@skypoint.com</a> | this distance" (last words of Gen.
.......................................| John Sedgwick, Spotsylvania1864)
<a href="http://www.pipingoffice.us/">http://www.pipingoffice.us/</a> =========================================Main site: <a href="http://www.pipingdesign.com">http://www.pipingdesign.com</a>
Yahoo! Groups Links Received on Tue Aug 30 06:10:00 2005
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