RE: hydrolic roughness

Hi group,
You can find a free on-line calculation for the Swamee-Jain equation at <a href="http://www.LMNOeng.com/moody.htm">http://www.LMNOeng.com/moody.htm</a> . If you look at the web page and wonder why the numerator is 1.325 instead of Steve's 0.25, it is because the on-line equation uses natural log in the denominator rather than common log. Enjoy!

Ken Edwards

> -----Original Message-----
> From: Steve McKenzie [mailto:Mechproj@xtra.co.nz]
> Sent: Friday, September 06, 2002 8:47 AM
> To: <a href="/group/PipingDesign/post?postID=SC_mkZ5WD1E70-4fx94afkmXDN45aLHSMd-HNw-RjYKSsO-3oou_CoHQ526g2lIfevvuWkakmo8YIw53Ss8IXFhWE2u8mWQ">PipingDesign@yahoogroups.com</a>
> Subject: RE: [PipingDesign] hydrolic roughness
>
>
> 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=SC_mkZ5WD1E70-4fx94afkmXDN45aLHSMd-HNw-RjYKSsO-3oou_CoHQ526g2lIfevvuWkakmo8YIw53Ss8IXFhWE2u8mWQ">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=SC_mkZ5WD1E70-4fx94afkmXDN45aLHSMd-HNw-RjYKSsO-3oou_CoHQ526g2lIfevvuWkakmo8YIw53Ss8IXFhWE2u8mWQ">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.
>
>
>
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> ask is for referrals for designs they help with.
> 877-610-8924.
> www.texasflange.com
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Received on Fri Sep 06 09:29:00 2002