EWS ... ah ... another acronym for the fire service. What is EWS? It means enhanced water streams.
This means there is an additive in the water to make it more efficient-i.e., foam concentrate or wetting agents. This past May, I had the privilege of working with the Kill the Flashover Project (KTF). A key component of KTF is researching fire behavior. The current research involves many facets of fire extinguishment including tactical air management (flow path management), the use of thermal imaging cameras, and EWS.
Why EWS?
Concentrates have been around for decades but are rarely used in structural fire suppression. Moreover, water works-and it's free-at least for the fire department. According to Albemarle (NC) Fire Department Chief Shawn Oke, concentrates aren't used because they are so misunderstood. Oke has studied concentrates, especially wetting agents, extensively and has written two executive fire officer (EFO) applied research projects on the subject. He is a strong advocate, as his entire fleet having wetting agent capability indicates. His department uses EWS for all fires. Oke is also a co-leader at the KTF research burns. One of this year's KTF burns was a comparison between a room and contents that were pretreated with plain water and a similar room that was pretreated using EWS. There were four notable findings in the comparison:
- EWS slowed progression of fire growth in the fire room.
- It reduced the risk of fire injury entering the "conditioned" area (hallway area pretreated with EWS).
- It decreased the rekindle chance.
- It increased the moisture in the fire room and "conditioned" room, allowing for an increased time of entry or reentry into the fire room.
Cost
Perhaps one of the biggest obstacles in embracing concentrates is the cost. There must be a delivery system on the apparatus unless the department wants to batch mix by adding concentrate to the booster tank. Then there is the cost of the concentrate. Many people equate EWS with aqueous film forming foam (AFFF) concentrate, which is proportioned at three to six percent. The concentrate mixture used with the EWS in KTF was 0.4 percent-not four percent but 0.4 percent. That is a huge difference. A little bit goes a long way.
Benefits
In the simplest of terms, EWS makes water much more efficient. Concentrates are surfactants and allow water to penetrate the fuel, thus improving the cooling capacity as well as minimizing runoff-i.e., unused water. As Oke states, the fire goes out quicker, the room gets cooler quicker, and the fire stays out. EWS is kryptonite for the embarrassing situation commonly referred to as "rekindle."
There is also an added benefit of EWS in the emerging world of fire suppression. There is a huge benefit in "conditioning." This means that EWS is applied to potential interior exposures as the fire attack team makes its way to the fire. Interior exposures can include walls, ceiling, floor, and furnishings. Conditioning adds moisture to the surfaces and humidity to the atmosphere. The concentrate causes the water to cling to the interior surfaces, whereas plain water will simply run off.
As just mentioned, humidity is added, and one might ask what the benefit of high humidity is. As Joe Starnes, who heads the KTF project, frequently says, "Try lighting a match in a sauna." The KTF project used positive-pressure ventilation (PPV) units with mist