Karen:

That just comes from time on the 'board' doing calcs over the years.  
Most of us that have been doing this for more than half of their 
lifetime can look at a building and get a general layout and rough idea 
of pipe sizes by knowing available pressures.  The calcs are just to 
confirm your best estimate.

On 2/10/2010 2:23 PM, Karen Purvis wrote:
> I'm not talking about calculations just about selecting the actual size of
> the pipe. Should I use a 1" pipe on 2 sprinklers or use a 1" pipe as long as
> the gpms are less than 10. I just want to know how people know or choose the
> size of pipe they use for each branch, sprig and main.
>
> Karen Purvis
> Senior Designer
> Facility Systems Consultants
> 713 South Central Street,
> Suite 101
> Knoxville, TN 37902
> ph.865-246-0164
> fax 865-246-1084
>
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of Matt Grise
> Sent: Wednesday, February 10, 2010 4:23 PM
> To: '[email protected]'
> Subject: RE: pipe sizing question
>
> In some of the jurisdictions around here the AHJ's do allow submittals
> without calcs for small add/relocate, and tenant improvement work as long as
> it does not exceed the original hydraulic design of the shell system
> (adjusting an OH2 retail system to accommodate a LH office, etc).
>
> I am familiar with the pipe drop charts you are talking about. The main
> issue I see with those is that it could be difficult to account for
> over-flow at each head, so you could end up with more water flowing than you
> anticipate.
>
> Matt Grisé PE*, LEED AP
> Sales Engineer
> Alliance Fire Protection
> *Licensed in KS&  MO
>
> 913.888.0647 ph
> 913.888.0618 f
> 913.927.0222 cell
> www. AFPsprink.com
>
>
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of Travis Mack,
> SET
> Sent: Wednesday, February 10, 2010 3:18 PM
> To: [email protected]
> Subject: Re: pipe sizing question
>
> It is my understanding that you need to provide calculations per NFPA
> 13, or use the pipe schedule method where it is allowed.  You can
> estimate with tables showing pressure drops, but that likely won't
> suffice for submittal to the local authorities in any where that I have
> done work.
>
> On 2/10/2010 2:08 PM, Karen Purvis wrote:
>    
>> We mainly do new and add-on systems a few retrofits no grids no high piled
>> storage no extra hazard. Usually all light and ordinary hazard.
>>
>> Karen Purvis
>> Senior Designer
>> Facility Systems Consultants
>> 713 South Central Street,
>> Suite 101
>> Knoxville, TN 37902
>> ph.865-246-0164
>> fax 865-246-1084
>> -----Original Message-----
>> From: [email protected]
>> [mailto:[email protected]] On Behalf Of
>> [email protected]
>> Sent: Wednesday, February 10, 2010 4:12 PM
>> To: [email protected]
>> Subject: RE: pipe sizing question
>>
>> For what kind of systems, new, retrofits, tree, grid, etc.....?
>>
>>
>> Craig L. Prahl, CET
>> Fire Protection Specialist
>> Mechanical Department
>> CH2MHILL
>> Lockwood Greene
>> 1500 International Drive
>> PO Box 491, Spartanburg, SC  29304-0491
>> Direct - 864.599.4102
>> Fax - 864.599.8439
>> [email protected]
>> http://www.ch2m.com
>>
>>
>> -----Original Message-----
>> From: [email protected]
>> [mailto:[email protected]] On Behalf Of Karen
>>      
> Purvis
>    
>> Sent: Wednesday, February 10, 2010 3:57 PM
>> To: [email protected]
>> Subject: pipe sizing question
>>
>> This may seem like a very newbie question but here goes. How do most of
>>      
> you
>    
>> guys size your pipe other than using a hydraulic calculation program? I
>>      
> have
>    
>> been using a pressure drop chart that list pressure drop and velocity in
>> schedule 40 pipe for water at 60°F per 100 feet drop. So far this has
>>      
> worked
>    
>> for me but now I have someone questioning my method. Should I be going
>>      
> back
>    
>> to the pipe schedule method?
>>
>>
>>
>> Karen Purvis
>>
>> Senior Designer
>>
>> Facility Systems Consultants
>>
>> 713 South Central Street,
>>
>> Suite 101
>>
>> Knoxville, TN 37902
>>
>> ph.865-246-0164
>>
>> fax 865-246-1084
>>
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>>
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>>
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>>      
>
>    


-- 
Please feel free to call if you have any questions or comments.

Sincerely,

Travis Mack, SET
MFP Design, LLC
2508 E Lodgepole Drive
Gilbert, AZ 85298
Office (480) 505-9271
Fax (866) 430-6107

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