 |
| Author | Post |
|---|
Far Galaxy
Member
| Joined: | Tue Jun 19th, 2007 |
| Location: | Apprx 32.2degrees N Latitude |
| Posts: | 1218 |
| Exams Taken: | | | Exams Passed: | | | Describes Me: | OFFICIAL |
| Status: |
Online
|
| Mana: |    |
|
Posted: Sun Jul 13th, 2008 05:27 pm |
|
I was reading a section called "condensation, or "sweating" in MEEB 8th page 580, and the 1st paragraph explained that groundwater in sume parts of the US is 50F and colder. A pipe carrying such water might have a surface temperature if about 60F. At a summer air temperature of 85degF, condensation will occur on this pipe when the relative humidity exceeds 40%. I went back to the chart on page 130 to trace it out, but I really don't know how they came up with that. If anyone out there got it figured out, please help me on this. I am so lost...
Thank you much.
Last edited on Sun Jul 13th, 2008 05:38 pm by Far Galaxy
|
Disgruntled
Member
| Joined: | Sat May 31st, 2008 |
| Location: | |
| Posts: | 115 |
| Exams Taken: | PD, BD/MM, CD, SP, BP, BT | | Exams Passed: | PD, BD/MM, CD, SP, BP, BT | | Describes Me: | my handle followed by the word INTERN |
| Status: |
Offline
|
| Mana: | |
|
Posted: Wed Jul 23rd, 2008 04:23 pm |
|
I will take a shot at this...
Since 60 degrees is the anticipated temperature of the surface of the pipe condensation will form on the pipe if the building temp is 85 degrees and 40% RH or higher. Thus the need for insulation
That can be determined by projecting up from 85 degrees (dry bulb) to where it intersects with 40% RH arc. and follow the dew point straight line to the left you are at about 60 degrees (I read 59 degrees).
I think in reality you would work this backward from 60 degrees (or whatever temp you think the summertime pipe temp will be) and compare to the anticipated indoor temperatures.
I also think this example is mainly to illustrate the need to insulate cold water piping.
|
polyarch
Member
| Joined: | Tue Feb 20th, 2007 |
| Location: | San Diego, California USA |
| Posts: | 164 |
| Exams Taken: | GS, LF, ME, BD/MM, CD, SP, BP, BT | | Exams Passed: | GS, LF, BD/MM, SP, BP, BT | | Describes Me: | |
| Status: |
Offline
|
| Mana: | |
|
Posted: Thu Jul 31st, 2008 03:23 am |
|
As disgruntled pointed out this is only a statement regarding condensation on pipes.
To help you understand the Psychrometric Chart a bit more I'll add my two sense. If we take this statement and make it into an example or question regarding your knowlege of the Pshychrometric Chart the question would read something like this:
If a building is planning on using groundwater as it's water supply and the air temperture above ground is 85F and the relative humidity is 42% (the statement says exceeds 40%), how warm does the groundwater need to be to prevent condensation?
>To Solve this problem draw a vertical line up the dry bulb temperture of 85.
>Where it crosses the curved relative humidity line of 42% then,
>Follow a horizonatal line to the left towards the dew point and it will read 60F
To prevent condensation the ground water needs to be warmer than 60F any thing less that 60F will create condensation on the pipes.
As the statement said when the air temperture is 85F and the Ground water is below 60F when the relative humidity exceeds 40% this will cause condensation.
Hope this make sense.
I think, that you could also back track the problem with just the tempertures. If the gournd water is 60F use the verticle line on the Chart untill you reach the dew point which happens to be 60F as well, then move right horizontally till you reach the 85F of the air temperture, this will give you the exact point when the relative humidity will cause the condensation!
-G
|
Current time is 02:20 am | |
|
|
|
|
