I have used, and seen others, successfully use a 2" NPT to 2.5" Nh adaptor on 
the Main Drain outlet and run 10' of hose to a 1.75" or smaller Pitotless 
Nozzle Hose Monster to measure the water flow.   This can give you an accurate 
water flow measurement.




PATRICK SPILLANE, CFPS

Director of Technical Products and Services

Dean of Hose Monster University

o: 888-202-9987

d: 847-598-0186 ext. 704

www.hosemonster.com<http://www.hosemonster.com/>

[signatureImage]

________________________________
From: Joe Meyer <[email protected]>
Sent: Wednesday, September 11, 2024 11:23 AM
To: Discussion list on issues relating to automatic fire sprinklers 
<[email protected]>
Subject: [Sprinklerforum] Re: [External]Re: main drain test

Just catching up on this - thanks for the referral Brian!

The drain estimator is only calculating the maximum possible flow from the 
orifice opening, for the purposes of accommodating the worst-case flow for 
drain sizing. The calculation is only incorporating pressure at an open-orifice 
(like the calc for the side outlet of a hydrant), but not the constriction that 
the main drain pipe and fittings have, nor the conversion from a total pressure 
to a normal pressure that the riser gauge is measuring.

Coincidentally (truly, weird) posted on this topic today: 
https://www.meyerfire.com/blog/the-trouble-with-estimating-main-drain-flow

The best way to verify the actual flow is to measure the flow itself (a bucket 
test or a pitot measurement), unless we build something to account for the main 
drain constriction and the conversion between normal and total pressure.

Joe

[https://ci3.googleusercontent.com/mail-sig/AIorK4w8V7wRmQweRoG0wzY1XiNWZMS3XP2cbBEB4tDJPicDAe-zpp1HFGE4s4vNn8CjGqShTYlKnS8]
MEYERFIRE, LLC
D: (636) 299-0339   E: [email protected]<mailto:[email protected]>   W: 
MeyerFire.com<http://MeyerFire.com> / MeyerFPE.com<http://www.MeyerFPE.com>
<http://www.MeyerFPE.com>
Licensed: AR, CA, FL, IA, IL, MO, WI



On Wed, Sep 11, 2024 at 11:14 AM, Craig Prahl 
<[email protected]<mailto:[email protected]>> wrote:

Maybe, maybe not.  You can get 775 out of a 2.5” hydrant outlet.



Craig Prahl | Jacobs | Fire Protection SME – Special Hazards | 
[email protected]<mailto:[email protected]> | 
www.jacobs.com<https://urldefense.com/v3/__http:/www.jacobs.com/__;!!KZTdOCjhgt4hgw!-_khxU8gU0_6jc895I7kRbnU8JghRDsWgqOblZ4jr7Qp2IVbR30VYw_hWvNFtphnl0uWpB9KIvbYi1pvZz4$>

1041 East Butler Road   Greenville, South Carolina  29606

CONTACT BY: Phone 1-864-676-5252, Email or MS TEAMS





From: Travis Mack <[email protected]<mailto:[email protected]>>
Sent: Wednesday, September 11, 2024 12:09 PM
To: Discussion list on issues relating to automatic fire sprinklers 
<[email protected]<mailto:[email protected]>>
Subject: [Sprinklerforum] Re: [External]Re: main drain test



775 gpm seems quite high coming out of a 2" pipe.  I would be skeptical of that 
number.





Travis Mack, SET

M.E.P.CAD | Instructor / Support

181 N. Arroyo Grande Blvd. #105 I Henderson, NV 89074

www.mepcad.com<https://urldefense.com/v3/__http:/www.mepcad.com/__;!!B5cixuoO7ltTeg!DESJQ7V4PW_ELv_hHW6JiceQ6AdeIMAcg5xv9AW6IjUapgf2gwOcv9FuTn62-0tbWDn4y7QS_JB0m0Qt$>
 | m: 480.547.9348| Whatspp: +14805479348

Email: [email protected]<mailto:[email protected]>



AutoSPRINK  |  AutoSPRINK FAB  |  AutoSPRINK RVT  |  AlarmCAD



________________________________

From: Rocci 3 Cetani <[email protected]<mailto:[email protected]>>
Sent: Wednesday, September 11, 2024 9:07 AM
To: Discussion list on issues relating to automatic fire sprinklers 
<[email protected]<mailto:[email protected]>>
Subject: [Sprinklerforum] Re: [External]Re: main drain test



Thanks Brian that’s helpful! Based on that the main drain is flowing 775 GPM



Rocci Cetani III, CET

Senior Designer

Water-Based Fire Protections Systems Layout, Nicet Level III





Northern California Fire Protection Services Inc.

16840 Joleen Way Bldg. A

Morgan Hill, CA 95037

P-(408) 776-1580 EXT.1010

F-(408) 776-1590



To help better serve you. Please visit our new and improved website at:

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From: Brian Harris <[email protected]<mailto:[email protected]>>
Sent: Wednesday, September 11, 2024 8:42 AM
To: Discussion list on issues relating to automatic fire sprinklers 
<[email protected]<mailto:[email protected]>>
Subject: [Sprinklerforum] Re: [External]Re: main drain test



Meyer Fire has an estimating tool for Main Drain test you might find helpful.



Thank you,



Brian Harris, CET

BVS Systems Inc.



From: Rocci 3 Cetani <[email protected]<mailto:[email protected]>>
Sent: Wednesday, September 11, 2024 11:38 AM
To: Discussion list on issues relating to automatic fire sprinklers 
<[email protected]<mailto:[email protected]>>
Subject: [Sprinklerforum] Re: [External]Re: main drain test



No clue but it gushes and its a lot of water….. To get that info we would have 
to put a PITOT on it



Rocci Cetani III, CET

Senior Designer

Water-Based Fire Protections Systems Layout, Nicet Level III





Northern California Fire Protection Services Inc.

16840 Joleen Way Bldg. A

Morgan Hill, CA 95037

P-(408) 776-1580 EXT.1010

F-(408) 776-1590



To help better serve you. Please visit our new and improved website at:

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From: Kyle.Montgomery 
<[email protected]<mailto:[email protected]>>
Sent: Wednesday, September 11, 2024 8:26 AM
To: Discussion list on issues relating to automatic fire sprinklers 
<[email protected]<mailto:[email protected]>>
Subject: [Sprinklerforum] Re: [External]Re: main drain test



Do you think, at 37 psi, that you’re pushing more than 361 GPM through that 2” 
drain?



Kyle Montgomery

 [cid:[email protected]]

Aero Automatic Sprinkler Co.

21605 N. Central Ave.

Phoenix, AZ 85024

Direct: 623.580.7820

Cell: 602.763.4736

[email protected]<mailto:[email protected]>







From: Rocci 3 Cetani <[email protected]<mailto:[email protected]>>
Sent: Wednesday, September 11, 2024 8:17 AM
To: Discussion list on issues relating to automatic fire sprinklers 
<[email protected]<mailto:[email protected]>>
Subject: [Sprinklerforum] Re: [External]Re: main drain test



6” feed in the stairwell with a 4” sectional and 2” drain



Rocci Cetani III, CET

Senior Designer

Water-Based Fire Protections Systems Layout, Nicet Level III





Northern California Fire Protection Services Inc.

16840 Joleen Way Bldg. A

Morgan Hill, CA 95037

P-(408) 776-1580 EXT.1010

F-(408) 776-1590



To help better serve you. Please visit our new and improved website at:

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From: Kyle.Montgomery 
<[email protected]<mailto:[email protected]>>
Sent: Wednesday, September 11, 2024 8:12 AM
To: Discussion list on issues relating to automatic fire sprinklers 
<[email protected]<mailto:[email protected]>>
Subject: [Sprinklerforum] Re: [External]Re: main drain test



What size riser and drain?



From: Rocci 3 Cetani <[email protected]<mailto:[email protected]>>
Sent: Wednesday, September 11, 2024 8:07 AM
To: Discussion list on issues relating to automatic fire sprinklers 
<[email protected]<mailto:[email protected]>>
Subject: [External][Sprinklerforum] Re: main drain test





Demand is 361 gpm  with 45 PSI @ BOR. Main drain test they are getting 37  
residual

Rocci Cetani III, CET

Senior Designer

Water-Based Fire Protections Systems Layout, Nicet Level III





Northern California Fire Protection Services Inc.

16840 Joleen Way Bldg. A

Morgan Hill, CA 95037

P-(408) 776-1580 EXT.1010

F-(408) 776-1590



To help better serve you. Please visit our new and improved website at:

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From: Steve Leyton 
<[email protected]<mailto:[email protected]>>
Sent: Wednesday, September 11, 2024 7:55 AM
To: Discussion list on issues relating to automatic fire sprinklers 
<[email protected]<mailto:[email protected]>>
Subject: [Sprinklerforum] Re: main drain test



Assuming that the demand from the calc area is for OH 1or 2 (and no inside 
hose), your demand is somewhere between 250 and 300 gpm If you modeled a full 
1,500 sq ft, no? And what is the residual pressure required?





Steve Leyton



Sent from my "Smart" Phone, so apologies for any typos or voice-to-text 
corruptions.







-------- Original message --------

From: Rocci 3 Cetani <[email protected]<mailto:[email protected]>>

Date: 9/11/24 7:19 AM (GMT-08:00)

To: 
[email protected]<mailto:[email protected]>

Subject: [Sprinklerforum] main drain test



We have a jurisdiction that failed our final inspection because the residual 
pressure during the main drain test doesn’t match our BOR residual pressure 
from the hydraulic calcs for and OH extended coverage system.  Am I missing 
something? I don’t see how the residual pressure on a main drain test has 
anything to do with the residual pressure  from our calcs…..I was always under 
the impression main drain tests were to verify there hasn’t been a been a 
drastic change to the supply . This was an existing parking garage where they 
added solar panels on the top level so we added a sectional riser @ the top 
floor and added the new system. The fire department just keeps saying to upsize 
the riser from the 1st floor to the 4th floor which literally does nothing to 
my calcs. The building owner has spent 10’s of thousands of dollars flushing 
the UG, inspecting the UG for obstructions, paid for additional flow test  and 
serviced the back flow.  We are at a complete loss on what else to do as the 
fire department is adamant that’s the main drain test has to match the 
hydraulic calcs…..anyone ever come across a situation like this with a 
jurisdiction? Any suggestions?



Rocci Cetani III



Northern California Fire Protection Services Inc.

16840 Joleen Way Bldg. A

Morgan Hill, CA 95037

P-(408) 776-1580 EXT.1010

F-(408) 776-1590



To help better serve you. Please visit our new and improved website at:

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