SprinklerDesigner2
Mechanical
- Nov 30, 2006
- 1,251
Georgia has some peculiar rules on standpipes with the 2003 edition currently adopted with a few changed that can be found here
120-3-3 State Minimum Fire Safety Standards - effective 03-09-2010
The change that affects me is found on Page 31:
So the way I read it as long as everything is 8" it sort of reverts to something similar to a manual standpipe system which are not allowed in Georgia except parking garages. Of course it isn't a manual standpipe system but without having to have a residual pressure requirement (the way i read it all we need is 2 lbs on top and we're good to go) it's sort of like a manual standpipe.
Tomorrow I am going to conduct a flow test but past experience in this area tells me to expect a static pressure of 65 psi and a residual pressure of around 40 flowing 1,000 gpm so by adding some heads, watching my head spacing and increasing pipe size I'm sure the sprinkler will be just fine given the fourth floor sprinklers are 50' (22 psi) above grade. This is the swamp area of Georgia and everything is exceedingly flat.
I really need to avoid a fire pump for two reasons.
First one is found in the State Minimum Safety Standards on page 33:
In the for what it is worth department the local people will not budge and there is also a regulation by the Georgia EPA that mandates a 20 psi suction pressure which specifically mentions "fire pumps" and there is no exceptions to the EPA regulation.
In this jurisdiction full flow meters and backflow assemblies are required and if the system has a fire pump, or a private fire hydrant, the backflow assembly must be an RPZ.
An 8" Ames 4000ss develops a head loss exceeding 10 psi when flowing and experience has shown me the manufactures lie. Maybe the assembly tested in the factory might be 10.3 psi but I don't care what their chart says whenever I have actually tested one, run a pump test putting a gauge at both the suction and discharge port of the assembly, my real loss has always been closer to 14 or 15 psi.
Then there is the tapping valve and sleeve. Anyone who believes an 8" tapping valve and sleeve carries the same equivalent fitting loss a standard MJ tee develops hasn't been around all that long. Rather than the 59' (C=150) Table 14.4.3.1.1 calls for I'll bet anyone here it's closer to 300'. What else to expect when the 8" tapping coupon measures 7" across?
Having that residual pressure drop below 20 psi during the pump acceptance test, usually one week before the grand opening, scares me to death because there is no easy way out.
The building is wood with composite floor joists so running 8" overhead won't work and I can see any structural engineer having a cow if I broached the subject.
So why not run the 8" underground outside the building as shown on the attached drawing?
I've run 8" before to avoid a pump but hanging inside wasn't a problem but something has me spooked on the underground layout. I am pretty darn sure it is fine but before I proceed, before I tell the owner it is possible only to have egg end up on my face, I'm sure everyone here understands that I need to 100% sure it's correct.
120-3-3 State Minimum Fire Safety Standards - effective 03-09-2010
The change that affects me is found on Page 31:
So the way I read it as long as everything is 8" it sort of reverts to something similar to a manual standpipe system which are not allowed in Georgia except parking garages. Of course it isn't a manual standpipe system but without having to have a residual pressure requirement (the way i read it all we need is 2 lbs on top and we're good to go) it's sort of like a manual standpipe.
Tomorrow I am going to conduct a flow test but past experience in this area tells me to expect a static pressure of 65 psi and a residual pressure of around 40 flowing 1,000 gpm so by adding some heads, watching my head spacing and increasing pipe size I'm sure the sprinkler will be just fine given the fourth floor sprinklers are 50' (22 psi) above grade. This is the swamp area of Georgia and everything is exceedingly flat.
I really need to avoid a fire pump for two reasons.
First one is found in the State Minimum Safety Standards on page 33:
In the for what it is worth department the local people will not budge and there is also a regulation by the Georgia EPA that mandates a 20 psi suction pressure which specifically mentions "fire pumps" and there is no exceptions to the EPA regulation.
In this jurisdiction full flow meters and backflow assemblies are required and if the system has a fire pump, or a private fire hydrant, the backflow assembly must be an RPZ.
An 8" Ames 4000ss develops a head loss exceeding 10 psi when flowing and experience has shown me the manufactures lie. Maybe the assembly tested in the factory might be 10.3 psi but I don't care what their chart says whenever I have actually tested one, run a pump test putting a gauge at both the suction and discharge port of the assembly, my real loss has always been closer to 14 or 15 psi.
Then there is the tapping valve and sleeve. Anyone who believes an 8" tapping valve and sleeve carries the same equivalent fitting loss a standard MJ tee develops hasn't been around all that long. Rather than the 59' (C=150) Table 14.4.3.1.1 calls for I'll bet anyone here it's closer to 300'. What else to expect when the 8" tapping coupon measures 7" across?
Having that residual pressure drop below 20 psi during the pump acceptance test, usually one week before the grand opening, scares me to death because there is no easy way out.
The building is wood with composite floor joists so running 8" overhead won't work and I can see any structural engineer having a cow if I broached the subject.
So why not run the 8" underground outside the building as shown on the attached drawing?
I've run 8" before to avoid a pump but hanging inside wasn't a problem but something has me spooked on the underground layout. I am pretty darn sure it is fine but before I proceed, before I tell the owner it is possible only to have egg end up on my face, I'm sure everyone here understands that I need to 100% sure it's correct.