Is a sprinkler technician, on any level (II, III, IV), allowed to make the 'engineering decision' of determining if a certain water supply is adequate? It appears this is supposed to be the PE or other design professionals job for the preliminary plans - but if he says the city water supply is adequate and there isn't enough water pressure when the system is fully laid out - are we then allowed to get a change order and get compensated for needing the extra cost of a pump, or are we given the responsibility to figure this out beforehand and absorb the cost?
Tek-Tips is the largest IT community on the Internet today!
Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!
-
Congratulations cowski on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!
Sprinkler Technicians vs P.E. in Determining Water Supply
- Thread starter fpst
- Start date
If the water supply is a public supply many times the Water Department will conduct the flow test,if at all. In some parts of the USA the Water Department will run a computer model and provide you with data. Sometimes a water flow test can take 2-4 months to get the results and cost you $500. So a lot of if's you need to figure out. Oh and sometimes the Insurance Company will conduct the water flow ( I did one today).
****************************************
Fire Sprinklers Save Firefighters’ Lives Too!
****************************************
Fire Sprinklers Save Firefighters’ Lives Too!
- Thread starter
- #5
In my 19 years of experience whether is done by an Engineer or a NICET technician the fact remains that water pressures are subject to change at any given time. However it is easy to find out if the individual performing such task is qualified to perform this task.
#1 Did he or she used updated equipment
#2 Was the equipment calibrated recently
#3 Is there a state clause that requires this individual to be certified
#4 Should the need of a pump be recognized at the time of the calculation and job specs on the design at that point
As an expert opinion in NJ I found that most mechanical engineers are not as qualified vs a NICET technician but yet you need a PE signature to at least generate drawings and calcs.
Yes you could be liable and responsible to absorb the cost but it is bound in a case by case
#1 Did he or she used updated equipment
#2 Was the equipment calibrated recently
#3 Is there a state clause that requires this individual to be certified
#4 Should the need of a pump be recognized at the time of the calculation and job specs on the design at that point
As an expert opinion in NJ I found that most mechanical engineers are not as qualified vs a NICET technician but yet you need a PE signature to at least generate drawings and calcs.
Yes you could be liable and responsible to absorb the cost but it is bound in a case by case
SprinklerDesigner2
Mechanical
One of my pet peeves.
Exactly how did he say it?
Just a "the water is good" is not good enough; how can any layout technician lay out a system without knowing what the water supply is? Short answer is he can't.
How about qualifying your bid with "the water supply is presumed adequate"? In my opinion that isn't good enough. If you can make the system work with a 12" lead in, 10" riser, 8" mains, 6" branch lines, 4" drops to pendent heads and optimal spacing to afford an end head pressure of exactly 7.0 psi then I guess the water supply would be adequate leaving the contractor no basis for a change order.
On the other hand if you clarified what your bid was based upon, "We assume a minimum water supply of 50 psi static, 40 psi residual flowing 700 gpm at the point of connection to the city water main" and it isn't then you are entitled to a change order. Of course with this sort of clarification it is wise to include the reason in your bid proposal such as "city water main not yet installed", "water utility could not provide flow test information prior to bid date" or whatever.
I understand your dilemma.
There are less than adequate engineering designs out there and there are less than scrupulous sprinkler contractors.
At least where I design, the engineers do not lay out the entire sprinkler system, so there are some "gaps" in our design. It is not until the sprinkler contractor performs the hydraulic calculations that it is determined if the water supply is adequate.
As the engineer, I try to forestall this in a few ways.
1. I try to get an updated flow test. But I know that sometimes from the time we get a flow test to when the construction ends can take some time. So I put in a blurb that the contractor is responsible to obtain a flow test if the construction information is more than 6 months old.
2. I indicate special areas of higher hazards, i.e. dry systems, preaction, OH2, EH, etc. which will require more than normal amounts of water and pressure
3. I indicate pipe sizes of mains, standpipes, up to the point of the floor control valve.
4. I do a rough layout from water service to most remote sprinkler, From this information, I state a maximum allowable pressure drop per 100 ft. of pipe. That way, no matter what size of pipe is used, I will have the required pressure and flow at the most remote sprinkler
This tends to prevent the contractor from using too small pipe to get the bid and then saying it doesnt work. If conditions are different, i.e. a new flow test indicates less pressure than originally designed for, the contractor is able to have a change order for increased costs of pump or other means to make it work.
So far, it seems to work out well.
There are less than adequate engineering designs out there and there are less than scrupulous sprinkler contractors.
At least where I design, the engineers do not lay out the entire sprinkler system, so there are some "gaps" in our design. It is not until the sprinkler contractor performs the hydraulic calculations that it is determined if the water supply is adequate.
As the engineer, I try to forestall this in a few ways.
1. I try to get an updated flow test. But I know that sometimes from the time we get a flow test to when the construction ends can take some time. So I put in a blurb that the contractor is responsible to obtain a flow test if the construction information is more than 6 months old.
2. I indicate special areas of higher hazards, i.e. dry systems, preaction, OH2, EH, etc. which will require more than normal amounts of water and pressure
3. I indicate pipe sizes of mains, standpipes, up to the point of the floor control valve.
4. I do a rough layout from water service to most remote sprinkler, From this information, I state a maximum allowable pressure drop per 100 ft. of pipe. That way, no matter what size of pipe is used, I will have the required pressure and flow at the most remote sprinkler
This tends to prevent the contractor from using too small pipe to get the bid and then saying it doesnt work. If conditions are different, i.e. a new flow test indicates less pressure than originally designed for, the contractor is able to have a change order for increased costs of pump or other means to make it work.
So far, it seems to work out well.
This is always a tough one.
Assuming the water flow data is available (and it is required to even estimate the requirements): It is hard for the engineer to determine for sure if the water supply is adequate without designing the system. But why design the system when the contractor is going to redesign it anyway (which is required to produce working drawings).
Let's say it is close: The contractor could design a 2" riser and say that the water supply is not adequate and needs a pump. The engineer would then say, use a 3" riser. On the other hand the engineer could bid a job out with a 50 psig water supply without any provision for a pump that may be close but when the contractor gets into it just can not meet the flow requirements.
Assuming the water flow data is available (and it is required to even estimate the requirements): It is hard for the engineer to determine for sure if the water supply is adequate without designing the system. But why design the system when the contractor is going to redesign it anyway (which is required to produce working drawings).
Let's say it is close: The contractor could design a 2" riser and say that the water supply is not adequate and needs a pump. The engineer would then say, use a 3" riser. On the other hand the engineer could bid a job out with a 50 psig water supply without any provision for a pump that may be close but when the contractor gets into it just can not meet the flow requirements.
- Status
Similar threads