The art of moving any volume of water over a long distance in firefighting operations is both time consuming in the setup and heavily weighted towards a large number of resources and skilled operators… if you’re not using LDH (Large Diameter Hose).
Example, twining the standard hose used (64mm) for delivery of 3000 LPM over a distance of 1200m will require a total of 21 pumps, which is a 21 times increased chance of a pump failure or operator error and not to mention the congested fireground. This consumes a large amount of resources and is extremely labour intensive to setup and pack up.
The cost to Fire Services can very quickly climb when conducting operations which involve moving water over long distances for extended periods. Also, the impact on local communities and businesses will be felt for some time after firefighting operations have completed at an incident.
In any pumping operations and especially relay pumping over a long distance, friction loss is our enemy, the smaller the diameter hose the greater the friction loss. Increase hose diameter and you will reduce the amount of friction loss and flow a higher volume of water, less energy is required to move that water. We often mistake increasing delivery pressure as a way of overcoming friction loss, but increased fluid velocity results in increased friction loss.
Inefficient relay pumping due to friction loss is determined by flow rate, hose size and length and sharp bends in hose. Other factors such as hose fittings and valves will also add to the amount of friction loss.
Just how much water is available to move to the fireground will be determined by the most important gauge on the pump panel, the compound gauge. As we increase delivery pressure, we should see a drop in compound pressure which indicates that we are moving more water. If we continue to increase delivery pressure and see no drop in compound pressure, then we have reached maximum efficiency and flow. Pressure doesn’t put fires out, flow rate does.
Scoresby CFA Fire Brigade located in Victoria Australia has spent the last 30 years running a Hose Layer and perfecting the art of relay pumping using LDH. In 2012 we started to look at new technology and worlds best practice. The old appliance with it’s 90mm canvas hose and manual retrieval method was no longer considered best practice and needed to comply with current OH&S Laws.
In 2014 we upgraded the old appliance to a new Hytrans unit with a HRU200 retrieval unit (purchased from Bluemont the Australian agent for Hytrans Fire Systems) All this technology and equipment was mounted on a Mercedes Atego 1629 cab chassis. Additional upgrades included changing from 90mm canvas hose to all 100mm extruded hose with Snaptite Storz couplings, 2300m in total length.
So now when we look at the same example job, with 100mm hose we only require 4 pumps total and can be setup and packed up with a crew of only 3. Friction loss on average for the 100mm will be around 10 kpa per 30m hose length. This is what we at Scoresby CFA call working Smarter and Not Harder.
By using world’s best practice and LDH, we have reduced the large amount of resources required, reduced the risk of operator error, reduced the duration of the fire fight and more importantly provided a safer working environment generally. Manual handling of hose while not totally eliminated, is greatly reduced due to the Hytrans HRU (Hose Retrieval Unit). The hydraulically powered HRU does all the work of lifting the hose back into the Hose Layer and only requires 2 x persons to guide the hose as it comes in.
Strengthening our relationship with local water authorities, has given us direct access to their watermain GIS Mapping remotely and further enhances our capability when it comes to selecting which hydrants and on which watermains we will source our water. The larger the watermain, the more available water we will have to deliver to the fireground. Volume is critical and pressure is only a consideration for the attack pump as it is all about the water volume and not delivery pressure.
As we see a shift in our climate, we are experiencing longer dry hot summers. The reduced rainfall has created additional challenges when sourcing adequate water for firefighting operations. The increase in population and thirst to consume more has resulted in an overload of waste processing facilities and landfill sites.
Large fires at waste recovery and recycling centres handling everything from general household waste to scrap metals and plastics are becoming more common. Water is generally not available in large volumes at these facilities and often reticulated water is not available.
Sourcing enough water for the firefight is critical, and this is where a hose layer carrying a large quantity of LDH really proves just how valuable a resource it is. Incident controllers need to factor in the hose layer when formulating the plan and make it part of the initial resource request.
The way forward for fire services in controlling and extinguishing large fires, and sometimes in remote locations, is to strengthen capability in resources. Large diameter hose is the answer to moving water from point A to point B in the most efficient way possible, this is the objective and proven many times by Scoresby Hose Layer and large diameter hose.
For more information, go to www.bluemont.com.au