Relay Pumping Going Digital?
Relay pumping can supply water over long distances, but existing equipment requires continuous monitoring of pressures and flows at each booster pump. A firefighter must be dedicated to monitoring and controlling each pump. In addition, each firefighter must be able to communicate with all of the other firefighters on the relay to ensure that pump pressure and flow changes are coordinated. On a long relay, a firefighter or a crew may be forced to remain at a location that might become dangerous. If they leave the location, the relay may fail.
Adding a data network to a relay system changes this scenario. The data network enables a single firefighter using a personal computer, or a touch-screen device connected to the computer, to monitor and control all of the pumps. The data network requires the addition of a small gauge wire pair onto the hoses used in the relay.
This article will explain how a ground-based data network system can be implemented as well as adapted for use in a helicopter.
Figure 1
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If existing fire roads are used, the hose can be deployed from reels mounted on 4WD vehicles (Fig. 1). The vehicles also carry a diesel or gasoline booster pump that is monitored and controlled by the network. Alternatively, if existing fire roads are not available, the hose can be deployed from reels mounted on tractors or plows (Fig. 2). Each tractor or plow would also carry a diesel or gasoline pump.
The relay system can be cached near a high-value facility and be rapidly deployed when there is a fire threat. There is no apparatus limit on the length of the relay, and the wire pair network can be added to both large- and small-diameter hoses.
All American Hose (which recently acquired Snap-Tite Hose) currently sells a fuel-carrying hose with a single embedded wire that is used to ground static electricity, according to Bob Harcourt, president. He explains that placing two wires in a hose is not a problem. Additionally, the voltages and currents in the data network wires are very small and harmless.
Many pump companies are using microprocessors to control the engines and pumps on firefighting vehicles. Mike Laskaris, engineering manager of Hale Pumps, says that it is possible to connect the microprocessors on his pumps to a data network that runs on the wire pair in the hoses. That hose data network can extend for many miles.
One example of a low-cost network is the LonWorks System from Echelon Corp. (http://www.echelon.com/). It was used in an application for Motorola in Scottsdale, Arizona, several years ago. An explanation of proposed uses for the system follows.
Figure 3
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The data network electrical signals in the wire pair on one hose must pass through the hose couplers to the wire pair in the adjacent hose. Fig. 3 shows a proposed new Storz-type hose coupler for connecting hose sections together. The proposed coupler does not require exposed electrical contacts that might be affected by dirt and water.
Each coupler contains an electrical coil that forms one half of an electric transformer. When the two couplers are connected, data network signals are transmitted across the coupler via magnetic fields. No metallic contact is required.
A small-diameter wire pair (24 to 16 AWG) will allow the Echelon Data Network to send its signals over long distances. Electrical repeaters at each pump allow the network to support any number of pump/hose sections.
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