I am thinking about getting a hydrant diffusor for hydrant flow tests but I feel uneasy about it.

[SprinklerDesigner2]

Call me old fashioned I have my 20+ year old brass pitot tube with gauges for pressures.

I am a true believer the most important part of my job is obtaining and verifying a correct flow test because without that anything I draw up is pure garbage.

I have my high quality oil filled gauges calibrated annually and I always include in any flow test report copies of my gauge certificates. I don't like the gauges "pre marked" for gpm discharge I prefer to use 29.83d^2 p^.5 which gives me the theoretical discharge to which I apply the 0.90 or whatever discharge coefficient I need to use.

Flow low flows I carry an underwriters playpipe with tip in the back of my vehicle. I recently conducted a flow test where we had 65 static, 29 residual with 303 gpm flowing through an underwriters playpipe. When we first opened the hydrant we couldn't get the pitot to register anything so I am glad the playpipe is among my toys.

I am thinking of getting a diffusor, something like this maybe [URL unfurl="true"]http://www.americanfirehose.com/sites/default/files/products/hydrantdiffusermerge.pdf[/url] but I don't know if I can trust the results. With the diffusor how can I explore the stream and know what I have is accurate?

But it would be nice to stop tearing up lawns.

If I did get one the first thing I would do is swap out their gauge for my certified gauge.

Anyone here use diffusors and what is your experience? Do you trust yours?

 

[LCREP]

At the Chubb Loss Control University we had several diffusers several of the kind you listed and played with them all. I liked this one the best because you got to use a hand held pitot tube and the diffuser worked well, my second choice was two hose monsters with built in pitot. We had crazy flows, static 130 psi, 110 residual with 1500 gpm flowing. We would let the students use just the hand held pitot tube 1st that was fun to watch, then shut it down and put the diffuser on, much easier and more accurate.

https://www.edarley.com/hydrant-dif...MIsfCP_6O22gIVC7jACh07ygWLEAQYBCABEgI1g_D_BwE

 

[cdafd]

Have not used one

Would say get one where you still need to hold a pitot gage

Plus read something about if you need two pitot readings and you use built in gage may not get good readings

 

[MGXFP]

I use the Pollard Hydrant Pro with a calibrated gage by a local laboratory.

https://www.pollardwater.com/produc...diffuser-phydpro160/_/R-4930322?skuId=4930322

The pitot tube location is static; its dimension set 4" away from and center of the snoot outlet. The ID where the pitot resides is 2.5" so the gage is as accurate as anything else, especially when results are rounded to the nearest 50 or 100 GPM as NFPA 291 requires. If you don't like the gage with GPM readouts you can swap for one reading only in PSI. The included gage has GPM and PSI.

It won't banish your play pipe as it isn't very reliable under 400 GPM.

After blowing sod and grass squares off new lawns using only a pitot tube and my wits I am very happy to be able to divert the flow to the street and other drain locations.

 

[LCREP]

The concern with pitot that is fixed in the device is one stone and you are done for the day and out $$$ for a new replacement. Hand held pitot are cheap without the gauge I used to carry 2 of them. That is another advantage of the diffuser I linked to. Also it really cut down on water discharge from a damage point of view.

 

[MGXFP]

Interesting point. I have used diffusers for 10 years and have yet to encounter a stone damaging the pitot.

I can just imagine my fury if that were to happen though! As a back up I always have a pitot tube in my truck just in case.

 

[LCREP]

Better go buy a lottery ticket....lol. I guess a lot of my flow testing was in new industry development with inadequate flushing of the mains. The diffuser I referred to has a lot of rocks in it after many tests ... go figure.

 

[bmlxd40]

I have used the diffusers a lot and I really like them. We also use hose monsters a lot and they are my 2nd choice.