Flow Test

[Sprinklerfitter]

We are looking at a project that involves an addition to an existing instituitional occupancy(University)in Ontario Canada. Existing flow tests indicate available flows as follows:
Static 68 PSI
Test 1-50 PSI @ 223 USGPM
Test 2-39 PSI @ 416 USGPM
Test 3-13 PSI @ 538 USGPM
Existing Hydraulic calculations show a most demanding area calc for the boiler room requiring 23.1 PSI @ 247.12 usgpm @ BOR plus 250 USPM hose allowance. What flow test results should have been used for this system design?
Thanks in advance.

 

[cdafd]

Any main drain tests been done in last few years???

 

[Sprinklerfitter]

No, building is only just a year old, new addition(s) will be light hazard but of course they are located as far as possible from the existing riser. I ask what test would have to be used because NFPA is not very clear on this point, NFPA 291 requires at least a 25% reduction in static pressure which would make any of the above tests acceptable however it also states that you must flow system demand, if this is inclusive of the hose stream it appears that the existing system is inadequate!

 

[SprinklerDesigner2]

Something smells really bad here.

Based on the information given the only flow test that would have any chance of being good was Test 2-39 PSI @ 416 USGPM w/68 static. Test 1 and 3 fail.

My major concern would be how the flow test was conducted. These flows are so woefully inadequate if the discharge was from a 2 1/2" hydrant it's irrelevant. I would have to think UL Playpipes were used for pitot readings.

The demand is base of riser but where was the test hydrant in relation to the base of riser?

 

[Sprinklerfitter]

I bet you can't quess what numbers the existing system has been designed too?? I can find nothing that requires the design contractor to use the most demanding curve, If test three had not been performed we would have no real indication of the water available! Can contractors arbitrarily choose curves to meet their design needs, can interpretted points on a graph such as those used in test two be used over real numbers such as those in test three? My gut tells me no, but it seems the wallet once again decides.

 

[skdesigner]

"Can contractors arbitrarily choose curves to meet their design needs"

Only the ones that can afford to spend the bulk of their time in court.

The inverse of that statement is true. "Contractors should choose design needs to meet the (water supply) curve."


-Why is test 2 not a "real" number?
-Do the tests show dates and times?
-What static pressure is the riser gauge showing?
-Can you perform a new flow test and put the argument to rest?
-By "interpretted", do you mean "interpolated"? You can interpolate or extrapolate points anywhere on the curve, though most water departments only let you take the curve down to +20psi.

NFPA 291-2010 4.3.6 To obtain satisfactory test results of theoretical calculations of expected flows or rated capacities, sufficient discharge should be achieved to cause a drop in pressure at the residual hydrant of at least 25% OR to flow the total demand necessary for fire-fighting purposes.

 

[Sprinklerfitter]

skdesigner,

Thank you for your response to this matter.

By interpret I mean "to construe the significance or intention of" in this case was it the stance of NFPA to only require a 25% drop in residual pressure? by adding "OR the total demand for fire fighting purposes" it indicates to me that they realize that more water may be required, it does not however stipulate that the contractor must use whichever is greater.
In this case if the contractor had stopped at test 1 as it meets the requirements of the standard for required drop in pressure this system would not work, the same can be said if only test 3 had been performed. Test 2 however works if the curve is carried beyond the amount of water that was actually flown at the time of inspection creating a theoretical availability.

 

[chicopee]

Hydrant flow test would be my first choice and then find out the pipe sizes to the sprinkler riser to determine flow availability at the sprinkler system .
What I don't understand is the wide fluctuations in your flow tests assuming that these were done by flowing the 2" drain connection.

 

[NJ1]

I would do it again. Both Hydrant and Main drain. Compare both and perform a new system analysis. Does not look good at the moment

 

[chicopee]

One more thing, make sure the street main water valve to your building is wide open whendoing a 2" drain test connection.

 

[Sprinklerfitter]

Thanks for the reply’s,

I posed this question to get everyone's opinion on what I see as a serious deficiency in the standard.
I can find nowhere in any literature that requires a contractor to flow a specific amount of water. The standard recommends that a 25% drop in residual pressure is achieved or the amount required for fire flow, however nowhere does it state SHALL. I feel this leaves a very large loophole for unscrupulous contractors to use tests that may or may not be sufficient.

Example:
New light hazard occupancy is being built at the end of an old, dead end 6” water main. Municipal pump house is located at the extreme end of the distribution system from the new buildings location, and a substantial elevation difference is present. Contractor (A) is awarded the job and is required to perform a flow test for the hydraulic calculations; all testing is to be performed as per the standard.
Contractor (A) performs three tests:

Static pressure is 68 psi at the gauge hydrant
• 50 psi @ 223 USGPM using 1-1 1/8 opening UL Play pipe
• 39 psi @ 416 USGPM using 1-1 ¾ opening UL Pay pipe
• 13 psi @ 538 USGPM using 2- 1 ¾ opening UL Play pipe

Test is completed and all results are recorded and returned to the office.
When the results are graphed the designer notes that only test 2 is “Capable” of meeting the system demand, now this is where I get concerned:

All the tests have achieved a 25% drop in residual pressure so per the standard any can be used for the system design, however any results extrapolated from beyond the point flown are technically theoretical. In this case because test three was performed we see that in actuality the distribution system is not capable of providing the required system demand. What is to say that the existing main has not been degraded to the point where its internal diameter is equal to that of a 2” pipe and only when it is flow beyond this capacity is this indicated? Test three seems to indicate that this may be a possibility, however nothing requires the contractor if they so choose or are ignorant enough to indicate this.

A 2” main drain test only indicates if a change in the distribution system has occurred since the original installation, it proves nothing as to the actual available flow! It is very rare that system demand can be achieved by a drain test.

Sorry for the long post.

 

[NJ1]

First the main drain is not intended to obtain any water supply data. I just dont understand why or how the 2" main drain falls into this conversation. I hope I am missing something on the text.

 

[cdafd]

Yes the main drain test got a little mixed up in this

It is suppose to show year to year a history

Can show if it goes to zero or near maybe valves closed