WATER CAD MODEL SOFTWARE
(I've done lab testing of fire hydrants for a client.) Consequently, if my fire flow requirement is 20 psi minimum at the flowing hydrant, I target anywhere from 24 to 30 psi minimum in the system.OpenFlows WaterGEMS provides numerous software capabilities for: At 1000 gpm, a typical hydrant will lose about 2 to 2.5 psi, and at 1500 gpm it might be in the 6 to 8 psi range. Many agencies want to keep emergency flows below 12 to 15 fps.Īnother thing: we typically model only the distribution system and not the hydrant lateral unless it's a long one, but even if we model the hydrant lateral, we don't model the hydrant itself. BTW, 1667 gpm through a 6" pipe is almost gpm is 11.4 fps. Of course, it is hard to get the larger flows through a 6" hydrant lateral and hydrant assembly, but for modeling you want to be conservative. Local codes differ, but the same type of procedure applies.ġ000 gpm < Q <= 2000 gpm: use 2 hydrants with 1000 gpm at the most critical and the balance at the other hydrant.Ģ000 gpm < Q <= 3000 gpm: use 3 hydrants with 1000 gpm at the two most critical and the balance at the third hydrant.ģ000 gpm < Q <= 5000 gpm: use 3 hydrants up to 1667 gpm at each, starting with the most critical. Back then, fire flows started at 500 gpm and incremented by 250 gpm above that to maximum of 5000 gpm. This is based on how the Los Angeles County Fire Department required it years ago. I've looped the system and was able to get greater flows, but it is not true representation of the model.īrett RE: WaterCAD Dead End Hydrant Model bimr (Civil/Environmental) 21 Oct 10 09:49įor modeling purposes, here is how I generally distribute the fire flows. I don't know if WaterCAD has some limiting capabilities regarding dead ends and reservoirs. It seems as though there is something limiting my amount of flow.Īny advice will be greatly appreciated. I increased all the pipe sizes to 24" except the 6" and can still only pull 800 gpm off.
I thought I should have adequate capacity to pull over 2500 gpm through a 6" pipe off an 8" off a 16", with sufficient capacity.
For example I can only pull 780 gpm off junction(3). It appears that my flow is being limited at junctions(2 & 3). This seemed unreasonable as the total distance from the 16" is less than 100 ft. I cannot get 1500 gpm at junction(2) or junction(3). I've run my typical scenarios and all the pressures stay within the reason of the 65 psi, everything looks good.
Junction(3) has a small demand added to the system. The model goes, reservoir - 16" line - junction(1) - 8" line - junction(2) - 6" line - junction(3). I've set up a model with a reservoir at an elevation equal to 65 psi. Existing infrastructure consists of a 16" main in the frontage road to the project with an 8" lateral stubbed at the project entrance.
I'm not extremely familiar with WaterCAD v8 and working on a smaller commercial site that needs a service stub and fire hydrant.