Hydrant flow test with static and residual obtained DOWNSTREAM the flowing hydrant on a dead end line.

[SprinklerDesigner2]

In my 50 years experience I always used an upstream hydrant to obtain a static and residual flow flowing the downstream hydrant.

What I am dealing with is a recently installed 6" dead end city water main that has a fire hydrant located about 100' from the fire sprinkler flange and spigot piece.

The underground is in and in operation but the interior fire sprinkler, light hazard building, has yet to be done due to the city water main extension which was literally finished last Thursday.

The closest upstream hydrant is 1,300 feet from the downstream hydrant and with 1,300' of 6" C-900 DR18 we can expect a friction loss of about 5.5 psi flowing 400 gpm.

For an accurate reading on the pitot I would use a UL/FM Playpipe with the 1 3/4" which offers the best accuracy in my opinion. I am experienced with this location and flows are generally not all that great which is why I want to use a playpipe.

I will probably use the 1,300 foot upstream hydrant for static and residual but what would be wrong with a gauge on the flange and spigot piece?

Let me add the land is completely level.

 

[cdafd]

Is the new fire hydrant ,,, the last one on the main?

I do not see why not put a gage on, just see what reading you get. Should not be much difference

 

[TravisMack]

As long as there is no backflow preventer or check / detector check valve on the lead-in, you should be able to get an accurate static / residual and then just flow the line downstream.

 

[SprinklerDesigner2]

Nothing in the line.

Direction of Flow
---->>>>>>>>
---------------------------0--------------------------X

0 Indicates Fire Hydrant
X Indicates Flange & Spigot
Distance Between Hydrant and Flange & Spigot is Approximately 75'

 

[TravisMack]

Oh. So you want to gauge it backwards? Sorry, I thought you meant that you had a public main with a lateral to your spigot and then continued on to a hydrant. I'd prefer to get a reducer on that flange and a hose valve so that you are flowing downstream of the gauge readings.

 

[cdafd]

So if fire. FD hooks up flows hydrant and robs sprinkler system?

 

[SprinklerDesigner2]

Oh. So you want to gauge it backwards? Sorry, I thought you meant that you had a public main with a lateral to your spigot and then continued on to a hydrant. I'd prefer to get a reducer on that flange and a hose valve so that you are flowing downstream of the gauge readings.

But between the hydrant and the flange and spigot there is no water moving so the residual pressure would be the same as if you attached a gauge one foot before the hydrant.

 

[cdafd]

Ok

How about put a fitting on the spigot so the play pipe could be used, for the flow??? Seen it done to flush a line