In my last blog, we discussed the small PRVs that go on wet sprinkler systems to limit their pressure below 175 psi. That brought to mind a small PRV in another application that is used to keep something different cool: an electric motor-driven centrifugal fire pump. I can’t talk about electric fire pumps without also talking about diesel fire pumps, so let’s dive in and take a look at both! (more…)
Ah, summertime. Summer’s heat brings some good things: opportunities for outdoor swimming and seasonal produce: blueberries, and peaches, and watermelon…
Summer’s heat doesn’t bring all good things. It can even trigger issues with fire sprinkler systems. Let’s zoom in on a small component on a wet fire sprinkler system that’s there in part because of summer heating: a pressure relief valve.
A pressure relief valve (or an auxiliary air reservoir) is required on wet sprinkler systems; one reason is to (more…)
In Part 1, we looked at the basic parts of a fire sprinkler and took a closer look at other parts including heat responsive elements, wrench bosses, and kick springs. In this part, we’ll look at k-factors and deflectors.
K-Factor and Orifice Size
K-factor is a characteristic that relates water pressure to flow rate from the sprinkler, represented as k in the equation Q = k√P, where Q is flow (gpm) and P is pressure (psi).
If we supply water at 50 psi to a k-factor 5.6 sprinkler, the flow rate is 40 gpm. If we supply 50 psi water to a K25 sprinkler, the flow rate is 177 gpm. There are now sprinklers as large as K33.6, which would flow 238 gpm given 50 psi – big difference from the K5.6!
The most common k-factors are 5.6, 8.0, 11.2, 14, 16.8, 22.4 and 25. There are smaller and larger k-factors than these. For reference, K5.6 and possibly K8.0 are most often found in (more…)
In this blog we’ll take a look at the basic and some of the less-known parts of fire sprinklers, with more to come in a later post.
Here are the basic parts of the fire sprinkler, shown on a pendent glass bulb sprinkler and an upright solder element (“fusible link”) sprinkler:
Let’s take a closer look to learn about some of the less known parts, and also look at two types of sprinklers disassembled. Included in parentheses are some of the different names for some of these parts. (more…)
In my two previous blogs, we first discussed wet sprinkler systems (Wet), the most basic and most common fire system type followed by dry sprinkler systems (Dry), which are a bit more complicated. Ratcheting up another level, in this last edition on sprinkler systems, let’s take a look together at preaction and deluge systems. These can be complex and variable, so we’ll operate at the 30,000 ft level. (more…)
In my previous blog , I discussed the most basic and most common fire system type: wet sprinkler systems. The possible failure areas discussed with wet systems will also apply to dry sprinkler systems (control valves closed, obstructions, issues in the system, installation, or deficiencies with inspection, testing, and maintenance). Dry systems are even more prone to obstructions than wet systems, so close attention should be paid to that possibility. (more…)
After a major fire, it is necessary to investigate the fire sprinkler system to see if and why it malfunctioned. Wet sprinkler systems are the most common and least complex fire sprinkler systems in use. The following are major items addressed in an investigation involving a wet system.
If available, drawings of the supply piping and sprinkler system are helpful. If these are not available, a sketch of the system will be made. Requests will also be made for inspection, testing, and maintenance documentation as well as fire alarm logs.
The top reason that fire sprinkler systems do not function correctly during a fire is (more…)
The ongoing frigid temperatures serve as a reminder of the many investigations by Warren engineers involving fire sprinkler systems that have failed when some part of the system was exposed to the sub-freezing conditions. Interestingly, failures do not necessarily occur within the area of greatest freeze exposure, as the failure mechanism is the extreme pressure that results from the growth of an ice plug inside the exposed pipe in which the high pressure will rupture the weakest component which may even be located in a heated area of the sprinkler system. (more…)