Must have been LinkedIn Nicky.
That K ( kPa metric ) looks like Coefficient of Discharge = 0.73.
If it's the angle valve I would use 0.62.
If it's the discharge outlet I would use 0.90.
This results in:
K=52.9 and 76.8 ( kPa metric ) respectively.
I always love hearing about how other parts of the world do sprinklers
so thanks for that.
The 'isolate' valve you explain is interesting!
Brad
Quoting Nicky Marshall <[email protected]>:
From a LinkedIn or sprinkler forum post sometime in the past, there
was advice given to simply use Q=K*sqrt(P)
K of 62.5 ( kPa metric ) for 50mm/2” valve
P is the town main static pressure
This seems to work well for us - it gives the flow rate that we
advise the drain needs to handle for a water supply ‘drain’ test.
We send this to storm water as we place an isolate valve above the
alarm valve so that ‘dirty’ system water is kept in the system and
this is fresh town main drinking water.
For drainage of sprinkler system we have a 100mm/4” drain to the sewer.
The sewer often can’t handle the volumes of the water supply ‘drain’
test which is why we split it.
Hope that helps
Nicky Marshall
Southern Regional Manager
PROTECH DESIGN LIMITED
Specialist Fire Protection Consultants
Phone: +64 (0)3 579 5577 extn 2 Mobile: +64 (0)21 433 488 Email:
[email protected]<mailto:[email protected]> Skype:
nicky-marshall Web :www.protechdesign.co.nz
Address:105A Alabama Rd, Redwoodtown, Blenheim 7201, NZ Postal: PO
Box 4022, Redwood Village, Blenheim 7242, NZ
“I always wondered why somebody doesn't do something about that.
Then I realised I was somebody” Lily Tomlin
From: Prahl, Craig/GVL <[email protected]>
Sent: Friday, 27 April 2018 9:20 AM
To: [email protected]
Subject: RE: main drain flows
The system design criteria has no bearing on what can be discharged
from the main drain.
You have a city residual pressure flowing through your riser and out
your system valve’s 2” drain outlet. What comes out will depend on
what’s coming in and the system pressure losses resulting from a
specific flow though the riser assembly and out the drain.
Craig Prahl | Jacobs | Group Lead – Fire Protection | 864.676.5252 |
[email protected]<mailto:[email protected]> |
www.jacobs.com<http://www.jacobs.com/>
From: Sprinklerforum
[mailto:[email protected]] On Behalf Of
Phillips, Mark
Sent: Thursday, April 26, 2018 5:10 PM
To:
[email protected]<mailto:[email protected]>
Subject: [EXTERNAL] RE: main drain flows
Tony
You should be able to do a rough calculation that will give you your
system demand. I would use that information to let them figure out
their own size.
Its just an estimate and I would reiterate that to them over and
over. You cannot supply final information until system is designed
completely.
[cid:[email protected]]
[cid:[email protected]]
Mark
Phillips
Vice President of Fire Protection
,
Kirlin Carolinas, LLC
t: 919-526-1584<tel:919-526-1584>
|
m: 919-610-0490<tel:919-610-0490>
[email protected]<mailto:[email protected]>
|
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8000 Brownleigh Dr
,
Raleigh
,
NC
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From: Sprinklerforum
<[email protected]<mailto:[email protected]>> On Behalf Of Tony
Cetani
Sent: Thursday, April 26, 2018 5:03 PM
To:
[email protected]<mailto:[email protected]>
Subject: RE: main drain flows
They are looking for the GPM flows out of our main drain during a
main drain tests. Since a lot of water is going to be released
during the test they want to make sure the sanitary sewer can handle
all the water with the main drain fully open under city pressure.
Tony
From: Sprinklerforum
<[email protected]<mailto:[email protected]>> On Behalf Of Steve
Leyton
Sent: Thursday, April 26, 2018 1:53 PM
To:
[email protected]<mailto:[email protected]>
Subject: RE: main drain flows
Tell them you want a hub drain with a self-priming 4” trap. It’ll
resolve both 1¼” and 2” main drain discharges.
Steve
From: Sprinklerforum
[mailto:[email protected]] On Behalf Of
Tony Cetani
Sent: Thursday, April 26, 2018 1:51 PM
To:
[email protected]<mailto:[email protected]>
Subject: main drain flows
Long time reader, first time writer…..actually not that long I’m a
fairly new designer. We have a jurisdiction where they require the
main drain to drain to a sanitary sewer and the contractor is asking
what the flows will be so they can size their SS line accordingly.
The sprinkler system hasn’t been designed yet and they said they
need to know right now so they can finish their design and submit
for permit. Is there a way to figure this out (or get a ball park)
just based off city water flow numbers?
Thank you
Tony
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