Tips for Using Aerial Master Streams

It’s pretty common to open this magazine or other fire service periodicals, or visit one of the fire service websites, and see photos of some big fires that require the use of master streams from an aerial ladder. It’s also pretty common to see poor-quality streams. But don’t just Monday-morning-quarterback these incidents. Several factors are required to produce first-class aerial streams, and when we’re looking at a photo, we rarely have all the facts about the incident. 

When we evaluate aerial master stream operations, we usually see one of two things:

  1. A good-looking stream of water coming from the aerial that has the appearance of a laser beam and is reaching the seat of the fire and making a difference in the firefight; or
  2. A weak, dribbling stream that looks like a rope.

Let’s take a look at some of the factors that make the difference between a high-quality and poor-quality aerial master stream.

Know Your Nozzle
There are lots of different types and configurations of master stream nozzles on the ends of ladders, so it’s difficult to establish hard and fast rules related to their use. The most important thing to remember: Know your own equipment and how to use it to your advantage. Two of the most commonly used types of master stream nozzles are smooth-bore and automatic.

You can see these in either a stacked tip set-up or single tip size that has been chosen by the department as their weapon of choice.

Stacking the tips is a good way of making sure you can produce a high-quality stream regardless of your available water supply: When you have a poor water supply, you use a small tip, and when you have a good water supply, you use a big tip.

The good and the bad of the smooth-bore: If you don’t have a good water supply or if it’s under-pumped, you’ll know by its appearance. But it also requires you to be a “thinking” firefighter because even in incidents with a very good water supply, the operator sometimes leaves all of the tips in place, restricting the flow.

Teaching point: When using stacked tips, be sure to add or remove tips as needed based on your supply of water or stream needs.

The automatic nozzle was designed to give a good stream, even when the water supply is lacking, and does so even if it’s under-pumped. This can also be a real disadvantage because the stream you see is good, giving you the perception that you have adequate fire flow, which may not be the case. Remember: On the fireground, it’s gpm vs. BTUs. You need the maximum fire flow that your equipment and water supply can provide.

A couple important points to remember when training on automatic nozzles on aerial ladders:

  • Know the manufacturer’s recommended operating pressure for the nozzle and pump to maintain that pressure. Also know the gpm rating for the nozzle.
  • If your aerial has a flow meter, make sure it’s calibrated–and use it! The flow meter is a good tool on aerials with automatic nozzles because it gives us something other than the appearance of the stream to judge the flow.
  • Pump for volume. When using aerial master streams, we’re attempting to overwhelm the fire, so use all your resources. Many operators are afraid to use higher pump pressures, thinking they’ll damage something. Increase the pump pressure to achieve the rated capacity of the nozzle (verified by the flow meter) or 20 lbs. of residual pressure from your incoming water supply. If the relief valve on the aerial activates, back the pressure down until it stops.

More Tower Tips
Tower ladders are awesome tools to use when you need heavy streams on a well-developed fire. They can flow at low angles of attack, get water into hard-to-reach areas and give firefighters a positioning advantage over other forms of attack.

Many tower ladders are equipped with two master stream nozzles on the front of their baskets. This can be a blessing or a curse depending on the crew’s actions. Some tips:

  • If you have two firefighters in the tower ladder basket, both want to put some fire out. Depending on how your department supplies your tower, this can lead to two poor streams if both are used at the same time. Remember that one good stream is much better than two poor ones that lack the reach and flow to make a difference in the fire.
  • Pay attention to the residual pressure from your incoming water supply; you may only be able to support one stream.
  • Connecting two supply lines from different sources into your tower will help to ensure that you have an adequate water supply and will provide a margin of safety if one of the supply lines is lost.
  • Use the right nozzle and stream for the job. A wide fog stream on an aerial works well to protect exposures, but it doesn’t fill the need to hit the base of a well-developed fire. Right tool (stream) for the right job (fire).

Even if you do use your ladder’s master stream device reasonably often, you still need to get out and flow some water on a regular basis. The fireground does not always provide the best environment for you to learn (or teach). So take time to understand your aerial device and its water flow capabilities and safety features. It’s a piece of equipment that’s too important–and too expensive–not to take full advantage of.

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