Common Mistakes In Residential Sprinkler Systems
At first it seemed the sprinkler contractors were at it again, attacking plumbing contractors for trying to get into the residential sprinkler business. This thought occurred to me as I read an article that appeared in the NFPA Journal at the end of last year. It was written by my good friend Russ Fleming, P.E. Russ works for the National Fire Sprinkler Association (the union sprinkler contractors group) and is one of the most knowledgeable people in the world when it comes to fire sprinklers. I also know that Russ is not the kind of guy who would take a slam at plumbing contractors trying to get into the residential sprinkler business.
After reading his article, I had mixed feelings. Russ did have some disparaging comments to make about plumbing contractors installing residential sprinkler systems. However, his comments were right on the mark. He simply pointed out that care must be taken when plumbing contractors enter the residential sprinkler business, and inspectors must pay close attention to the work plumbing contractors perform.
There have been mistakes made by plumbing contractors installing sprinklers. Like anyone involved in the fire sprinkler business, Russ wants the job done correctly. You should feel the same way. The last thing you need is to have an important safety system fail when there is a fire. Lives are at stake. Imagine the ramifications if a fire death occurred because a contractor did not follow the requirements of the standard.
In many ways, the article in NFPA Journal acknowledged that plumbing contractors would be getting into the
residential sprinkler business big time. As well they should.
Major MistakesSo, if you are in the business, contemplating getting into the business, or just want to sprinkler your own home, you need to know what practices to avoid. I have compiled a list of major mistakes I have seen plumbing contractors make on residential sprinkler installations. The list is in no particular order. Any one of these mistakes can result in a fire death. Hence, I give them equal weight.
- The sprinkler pipe is installed in 1/2-inch copper. By this, I mean that the plumbing contractor realized that the sprinkler had a 1/2-inch threaded connection, so the run from the main to the adapter fitting was piped in 1/2-inch copper. However, the minimum size in this case would have to be 3/4-inch copper. I should note that, in the latest edition of NFPA 13D, there is a provision for installing 1/2-inch sprinkler pipe. However, this sizing is limited to a looped system. There are several limitations for the installation. If you really want to run 1/2-inch pipe, find out all of the requirements.
- Hydraulic calculations were not performed for the design and installation. Quite often, a plumbing contractor
assumes that if he pipes the entire plumbing/sprinkler combined system in 1-inch pipe, then he will have no
problems. Some contractors never put pencil to paper and calculate the pressure and flow rates in the piping.
While you can get away with guessing when sizing a water distribution system in a home, you cannot do the
same thing for a residential sprinkler system. You must run the calculations for every installation.
Remember that more water flows through a fire sprinkler system than through a plumbing system. Additionally, sprinklers are more sensitive to the pressure demands in the piping system. If you don't know how to calculate the sprinkler pipe sizing, hire an engineer or sprinkler designer for each system.
- The plumbing contractor switches sprinklers. Plumbing contractors seem to be more attuned to the prices of
material than other contractors. For a nickel, some contractors will switch brands of products. The same has
happened in residential sprinkler installations.
Let's assume an engineer specified a specific brand and model of residential sprinkler for a particular job. The plumbing contractor gets a great price on a different brand, so he buys those sprinklers instead. You can't do that.
Every sprinkler installation is designed for a given make and model of sprinkler. Residential sprinklers are different from standard sprinklers. Furthermore, the manufacturers have individual ratings for each particular sprinkler. Flow rates and pressure requirements vary.
- Sidewall sprinklers are too close to the ceiling. I have actually seen plumbing contractors install sidewall
sprinklers as close as possible to the ceiling, thinking this would provide better protection. The deflector of a
sidewall sprinkler can be located no closer than 4 inches from the ceiling. Likewise, many models can be
located no more than 6 inches from the ceiling, unless they are so listed. (There are quite a few sprinklers
listed for being located up to 12 inches from the ceiling.)
If you install a sidewall sprinkler too close to the ceiling, the spray pattern hits the ceiling, preventing the water from reaching across the room to the other side.
- Sprinklers are located without due consideration for obstructions. I have seen sprinklers located right near a
soffit in the ceiling. If the sprinkler is activated, the soffit would obstruct the flow of water, preventing it from
hitting the fire. I have also seen sprinklers located alongside cabinets that would obstruct the flow of water to the fire.
Every conceivable obstruction has to be taken into consideration when locating a sprinkler. If the sprinkler does not have a direct line of sight with an area of a room, then it is not covering the area. Additionally, if a ceiling protrusion is close to a sprinkler, it may obstruct the flow of water. In residential sprinklers, the saying is the same one used by real estate agents: location, location, location.
- A valve can isolate the sprinkler. Plumbing contractors are so used to installing valves in a piping system that
they think nothing of throwing another valve on a residential fire sprinkler pipe. Unfortunately, you cannot have
a valve that will isolate only the sprinkler piping on a residential system. The valve must also isolate part of the
plumbing system so that it is obvious when the valve is in the closed position.
Treat any valve as if some idiot could come by and turn it off. In a sprinkler system, that can mean disaster. The only time you would find out is when you needed the system. And that would be too late.
I could probably list more mistakes, but these are some of the major biggies. Don't think that these mistakes are only made by plumbing contractors; sprinkler contractors have also made some of these mistakes.
Before getting hot and heavy into the residential fire sprinkler business, I strongly urge you to take a seminar or course on residential sprinkler systems. Get educated so that you provide the best system you can for your customers. If you haven't thought about the residential fire sprinkler market, make sure you get into the business, and soon.