RE: hydrolic roughness

From: <Steve>
Date: Fri Sep 06 2002 - 08:46:00 EDT

Hi babak rad

If you are talking about the friction factor, I normally use the Swamee Jain Equation:

f = 0.25/(log(k/(3.7*d)+5.74/(Re^0.9))^2

k is surface roughness in mm
d is pipe internal diameter in mm
Re is Reynolds number
  and f is of course the friction factor as used in the Darcy equation Hf= f*L/d*(V^2)/(2*g)

I find the Swamee Jain equation easier to use than the Colebrook White equation because no iteration is necessary.

For surface roughness, k, you will find these in books.

For starters, the standard ISO 5167-1 Appendix E gives some, a few of which are:

Brass, copper, aluminium, plastics, glass, new seamless cold drawn steel pipe: k<0.03mm
Other new steel pipe: k= 0.05 to 0.1mm
Rusty steel pipe: k= 0.1 - 0.3mm
Encrusted steel pipe: 0.5 - 2 mm and upwards for heavy deposits Galvanized pipe: 0.13mm
New Cast Iron: 0.25mm
etc

If you search the web, you are sure to find more. There appears to be more "roughness" information for the civil engineering head loss formulae such as the Hazen William and Chezy equations. With a little patience you can work backwards to calculate k from the coefficients that these equations use.

cheers

Steve Mckenzie

-----Original Message-----

From: Jacques Chaurette [mailto:jchaurette@fluidedesign.com] Sent: Saturday, September 07, 2002 12:16 AM To: <a href="/group/PipingDesign/post?postID=fmGVQHVCYsIY1CDmWMksPRCbOS-Xs3fG7gwaeTJZsCbKM2_r_wTUdguo8_ZVxopNqA9g4RPQEOIYmLRxPvnclYPohgg">PipingDesign@yahoogroups.com</a> Subject: Re: [PipingDesign] hydrolic roughness

You cannnot calculate roughness, this is something that must be measured.

Jacques

Jacques Chaurette
Fluide Design Inc.
<a href="http://www.fluidedesign.com">http://www.fluidedesign.com</a> tel (514) 484-PUMP (7867)
fax (514) 484-2294

• Original Message ----- From: BABAK RAD To: <a href="/group/PipingDesign/post?postID=fmGVQHVCYsIY1CDmWMksPRCbOS-Xs3fG7gwaeTJZsCbKM2_r_wTUdguo8_ZVxopNqA9g4RPQEOIYmLRxPvnclYPohgg">PipingDesign@yahoogroups.com</a> Sent: Friday, September 06, 2002 1:56 AM Subject: [PipingDesign] hydrolic roughness

   hi!

   i want to know that how can i calculate hydrolic roughness in a circular pipes?

   best regards.

   babak rad.

---

   Do You Yahoo!?
   Yahoo! Finance - Get real-time stock quotes

   [Non-text portions of this message have been removed]

         Yahoo! Groups Sponsor
               ADVERTISEMENT

   Texas Flange - a good source for information on industrial flanges, all they ask is for referrals for designs they help with.

   877-610-8924.
   www.texasflange.com

---

   unsubscribe: <a href="/group/PipingDesign/post?postID=vjesblTVvW3m6fFn3Hsk1YE_x118P-md3Ci75RYI6tDZuQR2Uwi6YPc1YkEx7B2o4l3pFLjT0rUQ9TXcRwY0HxTMQOL_eYEUdUj4RXZlr8U">PipingDesign-unsubscribe@yahoogroups.com</a>

   Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.

[Non-text portions of this message have been removed]

Texas Flange - a good source for information on industrial flanges, all they ask is for referrals for designs they help with. 877-610-8924.
www.texasflange.com

---

unsubscribe: <a href="/group/PipingDesign/post?postID=vjesblTVvW3m6fFn3Hsk1YE_x118P-md3Ci75RYI6tDZuQR2Uwi6YPc1YkEx7B2o4l3pFLjT0rUQ9TXcRwY0HxTMQOL_eYEUdUj4RXZlr8U">PipingDesign-unsubscribe@yahoogroups.com</a>

Your use of Yahoo! Groups is subject to <a href="http://docs.yahoo.com/info/terms/">http://docs.yahoo.com/info/terms/</a>

---

Incoming mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.384 / Virus Database: 216 - Release Date: 8/21/2002

---

Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.384 / Virus Database: 216 - Release Date: 8/21/2002 Received on Fri Sep 06 08:46:00 2002