The Fire Factor
Q. On a recent inspection we stumbled onto this inspector’s test connection for a wet-pipe system (see photo) that was not piped to any sink or drain, and simply terminated in a 1-inch plug. Is this configuration in violation of code?
A. It certainly is. This is something to definitely flag in your report. Cite section 126.96.36.199.3 in (2007 ed.) NFPA 13 for inspector’s test connections, which reads that “the discharge shall be to the outside, to a drain connection capable of accepting full flow under system pressure, or to another location where water damage will not result.”
Q. We have a small dry system in an unheated portion of our warehouse, with about a 175-gallon capacity. The air compressor servicing the system kicks on and runs about eight or nine times per day. My plant manager says this is no big deal, but is it?
A. You definitely have a problem. A system that small, if it contains grooved couplings, should be losing only about 1 psi every 24 hours. Your compressor should be kicking in only about once per week. If you told me it kicks on once daily, I wouldn’t be overly concerned. But the gaskets in the grooved couplings often dry out over time and lose their ability to maintain a tight seal. Your system should be trip-tested as soon as possible and then tested again annually. This exercise allows you to flood the system, which usually causes the gaskets to seal more effectively.
Q. We have been using a conversion table for our flow tests that apparently is not 100% accurate. How can we check the gpm results from this table? For example, the latest flow test we conducted, in which we opened one 2-½-inch port with a 0.90 coefficient on the fire hydrant, yielded a steady reading of exactly 27.5 on the pitot gauge. What would be the total flow in that case?
A. A fire sprinkler system is only as good as its water supply, so it’s imperative that these test results are computed with accuracy. For your test, the total gpm flow is determined by multiplying four numbers. These are the hydrant coefficient (0.90 for a smooth rounded outlet), the square of the hydrant butt orifice, the square root of the pitot gauge reading, and a constant of 29.83. Your total, then, would be 0.9 X 6.25 X 5.244 X 29.83 = 880 gallons per minute. I hope this matches what is shown on your conversion chart and, if not, your chart may not be reflective of results for hydrants having smooth bore rounded outlets.
Q. We’re installing upright sprinklers on branch-lines that run through the A’s and V’s of bar joist construction. Some of the sprinklers are coming very close to the joists. I know that we have to be 12 inches away from the joist when installing ESFR sprinklers, but what about standard large-orifice sprinklers with a K-factor of 8.0?
A. For years the general rule of thumb was a minimum of 3 inches for this application. The intent is to maximize the effectiveness of the sprinkler discharge while minimizing the “dry shadow” on the opposite side of the structural obstruction. What the code says (NFPA 13: 188.8.131.52.1.3) is that “sprinklers shall be positioned away from obstructions a minimum distance of three times the maximum dimension of the obstruction.” This “Three Times Rule” is only applicable when the obstruction is not solid or continuous. In your case, if the bar diameter is 1 inch, the sprinkler deflector must be a minimum of 3 inches away. If you are using extended-coverage upright sprinklers (see 184.108.40.206.1.3) this rule changes to a “Four Times Rule.” One code requirement often overlooked concerns the obstruction posed by the bottom of the bar joists, and appears in section 220.127.116.11.1.7, stating that the sprinkler deflector be positioned at least 6 inches above that structural portion of the joist.
A. The NFPA says very little definitively about this issue. What is does say with regard to hydrants is contained in Chapter 7 of (2007 ed.) NFPA 24. The key passages are these:
18.104.22.168: “The number, size, and arrangement of outlets; the size of the main valve opening; and the size of the barrel shall be suitable for the protection to be provided and shall be approved by the authority having jurisdiction.”
7.2.1: “Hydrants shall be provided and spaced in accordance with the requirements of the authority having jurisdiction.”
7.2.3: “Hydrants shall be located not less than 40 ft. from the buildings to be protected.”
In other words, your fire department has complete autonomy over this situation, and can rule their kingdom as they see fit. The reasoning behind Section 7.2.3 is that the NFPA would like to avoid or minimize any possible firefighter injury from falling walls - so they want the hydrants situated at least 40 feet away. The other sections seem to be very “politically correct” and designed not to ruffle any AHJ’s feathers. This is what the (NFPA 24) code used to say on the matter (1977 ed.):
4-2.1: “A sufficient number of hydrants shall be installed to provide two streams for every part of the interior of each building not covered by standpipe protection and to provide hose stream protection for every exterior part of each building by the use of the lengths of hose normally attached to the hydrants. There shall be sufficient hydrants to concentrate the required fire flow about any important building with no hose line exceeding 500 feet in length.”
The primary function of a fire department connection is to serve as a secondary source of water in case one of the main sprinkler system control valves has been accidentally shut off. To require the provision of a hydrant within 100 feet of a fire department connection seems a bit excessive to me. But with regard to this jurisdiction, my guess is that they have some emotional investment in their territory, which justifies what they write in their own ordinances. They may also be aware of the limitations of their own equipment, and are establishing reasonably conservative parameters in the interests of fire protection and life safety.
Q. Our community uses older model codes as adopted legislation, and our contractor has installed a pull station 5 feet off the floor level, and is being asked to move this lower so that it may be handled easily by the general public, including children. Where does it say in the code that 60 inches is too high for pull stations?
A. The building codes supersede NFPA 72 on this matter. If your village uses the IBC, then you are limited to a pull station elevation that is between 48 and 52 inches above the finished floor. BOCA (1993) section 917.5.1 reads that “the height of the manual fire alarm boxes shall be a minimum of 42 inches and a maximum of 54 inches measured vertically, from the floor level to the activating handle of the box.” The same wording would appear in section 918.5.1 of the 1996 BOCA. This issue is usually addressed in the contract documents by the electrical engineer. BOCA also stipulates that these pull stations must be red. If this is an old job, whoever installed these manual fire alarm boxes will probably still have their name and number located somewhere on the fire alarm control panel. Give them an informative heads-up.