Supplying Aerial Master Streams-An Overview

It’s important when supplying aerial master streams to understand the key factors involved, and understand the limitations of the hose and the aerial device you are using.

First, many departments opt to use 4" or 5" Large Diameter Hose (LDH) to handle all of their water supply needs. There are two general categories of this type of hose, supply or standard grade, which has a service pressure of 200 PSI and attack grade or high pressure which has a maximum service pressure of 300 PSI. Some brands may offer higher service pressures too. For the sake of safety, we always say to deduct 10% from the maximum service pressure of the hose. That means that if you are using supply grade, your max pump pressure is 180 PSI, and if you are using attack grade your max pump pressure is 270 PSI.

Aerials have inherently high pressure loss, as the waterway has some sharp bends in it to allow the piping to make its way up the center of the turntable. It’s not uncommon to see four 90 degree elbows. These bends and elbows represent extreme inefficiency, and will require higher pump pressures to overcome them.

Aerials also suffer from the effects of head pressure loss, as the weight of the water in the aerial exerts back pressure downward and requires higher pump pressures to overcome it. Elevation loss is .434 PSI per foot. It’s easier to represent that as .5 PSI per foot. This means that for every 10 feet of elevation you are losing 5 PSI due to head pressure loss.

It is hard to say exactly what the pressure loss in the piping of an aerial is, until you run actual flow tests. It is, however, safe to say that the loss is typically no less than 50 PSI, and in some cases as high as 100 PSI. Remember, pressure loss (due to flow of water) rises almost exponentially as flow increases, so an increase in flow of every 500 GPM doesn’t mean the pressure loss value is an equal value for each flow increase. For example, the pressure loss in 5" hose for 500 GPM is 1.7, for 1000 GPM it is 6.0, for 1500 GPM it is 15 and for 2000 GPM it is 27. So you can see that the difference in pressure loss from 500 GPM to 1000 GPM was only 4.3, but the difference between 1500 GPM and 2000 GPM was 12.

The last issue at hand is the nozzle. Remember, a nozzle represents restriction. The higher the nozzle pressure must be, the more restriction/backpressure and the harder your pump must work to overcome it. Using a smooth bore tip on an aerial monitor will lower your supply pump pressure 20 PSI compared to using a 100 PSI automatic nozzle, because the smooth bore only requires 80 PSI at the tip for its "rated flow". So, for an equal flow the smooth bore requires a lower pump pressure. Don’t forget that all the other restrictions in flow in the aerial and the elevation are still in play though.

What if the aerial has a pump? Whenever possible, supplying an aerial that is equipped with a pump, it is hydraulically sensible to use the pump to boost the incoming pressure so that you can overcome the restrictions in the rig itself. The one instance where this is not desirable is if the aerial rig is a Quint and it is operating handlines at the same time. The volume of water and required pressure flowing for the aerial master stream, coupled with handlines being used can cause the risk of overpressurizing the handlines if the master stream is shut off and the pressure governor or relief valve isn’t capable of managing the extra water surge. It is recommended that if the aerial is operating handlines off its pump, to use a separate supply pumper to feed the aerial directly through its rear inlet.

Let’s look at the factors that come into play again, using the pump discharge formula;

PDP=NP+FL+DL+EL

Where;
- PDP=Pump discharge pressure
- NP= Aerial nozzle TIP pressure – 80 PSI for Smoot Bore, 80 or 100 for Fog, check tip for exact pressure
- FL=Friction/pressure loss in the HOSE
- DL=Device loss, in the aerial piping-unknown exact value unless tested
- EL=Elevation loss - .5 PSI per foot

Using some numbers taken from an actual aerial flow operation I recently participated in, we were able to prove this theory. A 100 foot aerial tower, with a 100 PSI automatic nozzle was only able to flow 900 GPM through two 100 foot lengths of supply grade 5” hose. The supply pumper was operating at 185 PSI. The aerial was only off the ground approximately 25 feet, for most of the operation. We were able to deduct the pressure loss in the aerial piping at around 75 PSI, because the nozzle pressure was 100 PSI and the pressure loss in the hose was about 10 PSI. With a pump pressure of 185, subtracting the nozzle pressure (100) and the pressure loss in the hose (5 PSI per 100ft, for a total of about 10 PSI) the remaining 75 PSI represents pressure loss in the aerial waterway. The waterway on this particular rig is capable of 1500 GPM. The hose limited us to 900 GPM. The investment into better hose or use of multiple 3” lines would allow maximum water flow in this particular evolution.

So what does all this mean? Using standard grade supply hose is not the best choice for supplying an aerial master stream unless you are supplying the rig through its pump, if it is so equipped. 3” or 3 ½” hose is a good option if you still carry it, but the better long term solution is to switch over to attack grade LDH. If your budget is limited, having a few lengths of attack grade supply hose on the aerial rig is a good interim solution. Make sure your apparatus operators know that they need to use this hose when the rig is being supplied through its rear inlet.

The bottom line is that if you want to flow an aerial at its maximum capable flow, you must forecast the approximate required pump pressure ahead of time and have hose that is capable of delivering the required pressure at the inlet, to get the desired flow out the tip. To break it down into simple terms, pump through the shortest required length of hose, and use the highest pressure rated hose possible to supply aerials. If your LDH is supply grade, assure you have an appliance to allow at least three 3” or 3 ½” lines to be used to feed the inlet of the aerial.

If you only carry supply grade 5" Hose, (rated to 200 PSI), consider supplying aerials with no pump using multiple 3" lines so you can provide the proper pressure to the inlet. In this instance, each 3" line is only flowing about 350 GPM, as the tip flow is around 1100. Because this hose is rated to flow at pressures up to 400 PSI, it makes it a no brainer to supply this aerial. Without knowing the pressure loss in this rig, we know that at an elevation of 100 feet, the head pressure loss is 50 PSI, the nozzle pressure is 80 PSI and the pressure loss in the hoselines is 10 PSI. That is a pump pressure of 140 PSI, without factoring in the aerial piping pressure loss, which is often at least 50 PSI. The potential pressure for this aerial to flow 1100 GPM is AT LEAST 190 PSI if it is 100 feet away from the supply pumper using three 3" lines.

This rig has 1100 feet of 5" in each bed, the left bed is supply grade hose the right bed is attack grade hose.

If youy only carry supply grade 5" Hose, (rated to 200 PSI), consider supplying aerials with no pump using multiple 3" lines so you can provide the proper pressure to the inlet. In this instance, each 3" line is only flowing about 350 GPM, as the tip flow is around 1100. Because this hose is rated to flow at pressures up to 400 PSI, it makes it a no brainer to supply this aerial. Without knowing the pressure loss in this rig, we know that at an elevation of 100 feet, the head pressure loss is 50 PSI, the nozzle pressure is 80 PSI and the pressure loss in the hoselines is 10 PSI. That is a pump pressure of 140 PSI, without factoring in the aerial piping pressure loss, which is often at least 50 PSI. The potential pressure for this aerial to flow 1100 GPM is AT LEAST 190 PSI if it is 100 feet away from the supply pumper using three 3" lines.

Because supply grade 5" hose was used to feed this tower, a maximum flow of around only 900 GPM was available, even though the waterway can flow up to 1500 GPM. This was only a 200ft lay. The supply pumper was providing 185 PSI at its discharge. Doing the math, we can deduct that the pressure loss int he hose is about 10 PSI, at the flow of 100 GPM, and the nozzle is 100 PSI at the tip. That means the pressure loss in the aerial is about 75 PSI.

Using 2 100ft lengths of standard supply grade 5" hose, we could not provide more than 900 GPM to this aerial. It has a 1500 GPM waterway and the hose was maxed out at 185 PSI, at low elevation.

This 1250 GPM single stage pumper easily supplied a 1400 GPM tower ladder which is not equipped with a pump.  The tower is equipped with stacked tips and is being fed utilizing attack grade supply hose.  In addition, the rig flows 500 GPM from its wagon pipe, for a total of 1900 GPM

Pump pressures on the panel of the 1250 GPM engine show high loss between the master discharge and the line gauge for the 3" LDH discharge.  Specing larger valves will improve efficiency

The summary of all this is that if all you care about is having water come out the nozzle tip, then carry on as you were, if you want to deliver the aerials capacity, or understand how to achieve that, you must conduct flow tests, then be equipped with the proper hose, nozzle and appliances.

Whats in a Photo?

We know what happened here-but we don't know why, its not our photo.

There are dozens of firefighting web blogs and Facebook pages on the internet, many of them are incredible sources of information, and present diverse and thought provoking topics, photos and questions.  Each sites owner(s) have a style, its what makes them all unique.  This site has a style too, its pretty simple.  Most of our stuff is ours.  We post photos, videos and information that we have personally been involved in.  We like to share photos and videos from other major sites, that might present some interesting perspectives, but the majority of our content comes from our site contributors.

Why does it matter, you may ask?  Take a look at some of the sites out there, the sites that grab one of your photos and ask the world how they would have handled the operation.  How can you moderate the discussion objectively if you cannot speak for the events that took place during that situation which is depicted in the photo?  Its hard to do, everyone should agree on that.  By posting our own photos and videos, its easier to address questions, comments or concerns, when we have access to the people involved, to understand their thought processes in those moments.

the driver of this engine quickly rectified the kinked supply line

So brings the question; is it OK to use other photos and videos as food for a discussion?  I think the answer is a conditional yes.  We have to remember how many variables exist that we cannot fairly identify.  We also need to remember how small of a time window exists when a photo is snapped.  It makes it somewhat of a double edged sword to use any photo as a focal point for discussion, but at the same time, we need to be able to fuel our critical decision making skills and gain insights and feedback from others.

We will always make an effort to post photos tat we can explain and articulate.  In cases where we find a photo or content from other sites that we find interesting and informative, we will share it here and indicate such.  We enjoy the constructive nature of everyone's feedback, its made the site very easy to moderate and administer.  Than you for your continued contributions.

Protect Yourself From Potential Failure of the Devices that are Supposed to Protect You

Large diameter appliances and externally mounted relief valves are found on many rigs.  These devices are critical for safe operation when working with high volume large diameter hose.  An often overlooked issue, is the testing of the relief valves on these appliances.  An improperly adjusted relief valve can lead to a few dangerous issues including but not limited to;

• Burst supply hose due to hose service pressure below the relief valve pressure (Supply grade LDH-200 PSI)
• Failure to open in an overpressure
• Opening at too low of a pressure and dumping critical water, which may be a nuisance, or cause icing.

Some hose testing companies offer appliance testing, but many do not.  For departments that conduct hose testing,  these appliances should be tested along with your hose, at least annually, with the consideration given to more frequently.  Kochek, a large manufacturer, recommends every 6 months.

Here are two links that reinforce the necessity for testing of the appliances;

http://www.state.nj.us/dca/divisions/dfs/reports/hampton_township_ff_Injury_rpt.pdf

http://www.chenangofireems.com/uploads/files/Manifold%20Failure%20Test%20Report.pdf

This is the result of an appliance failure.  Courtesy Lambertville, NJ FD

In both of the previous reports, it was fortunate that there were no fatalities.  Be cautions around these appliances, at all times, not just when testing them.

Testing isn't to be taken lightly.  Any time you are service testing equipment, you should expect it to fail, that is, to take the proper precautions to prevent injury and damage.  Proper head, eye, body and foot protection are a must.  Following appropriate testing standards is another important consideration.

NFPA 1962 recommends testing of appliances to the manufacturers standards.  Kochek happens to offer a guide for doing just such a test.  It can be found here; http://www.kochek.com/docs/PressRelief_Valv_%20TestProc_Web.pdf  Within the 1962 document, there lacks substantial step by step guidance, but rather it has general recommendations.  The document can be viewed at www.nfpa.org

When you raise the throttle, the gauge will "pop" when the relief dump valve on the appliance opens and should not rise above that as the pump pressure continues to rise.

Testing these appliances can be done in house, if you follow the above recommended guidance.  A few points to note are as follows;

• Expect a catastrophic failure of an appliance.  If the appliance has ever been dropped or damaged, and not inspected, it should be removed from service and checked by a qualified professional, to include x-ray inspection of applicable.  Invisible manufacturing flaws may not be evident, use care.
  
• It is a good idea to attach the appliance being tested to a section of hose to move it away from the rig and personnel prior to testing.  CAUTION:  Check the service pressure of the hose you are using, and do not exceed it.  This means that standard supply grade LDH (single jacket rubber type) will not be sufficient for testing over 200 PSI.
  
• Inspect the devices for any obvious corrosion or deficiencies prior to testing.
• ALWAYS consult the manufacturer for their recommended testing and the rating of the appliance being tested.
• Air trapped in appliances represents greater stored energy potential, and if not bled can cause a more catastrophic failure if such were to occur.

Bleed the air from each discharge at idle before pressurizing the valve.  With the pump discharge barely opened, a small stream of water is all that should be exiting when you crack the valves.  Once you close the valves on the appliance, the water pressure inside the appliance will increase slowly as the low volume of water from the discharge comes up to pressure.

The relief dump valve has opened properly here.  Take note that on manifolds such as this, the relief valve only protects the appliance with the valves in the closed position when it is used as a DISCHARGE manifold (Supplied from the single inlet side), not in reverse, being fed by several lines.  Also, note the allen wrench in the relief valve set screw used to adjust through its range.

Test the air bleeder on intake valves.  Bleed the air out at idle before pressurizing the valve.

If you test the appliance connected to the rig, do not connect it to the same side as the operators panel where you will be standing.

Many newer apparatus have intake relief valves which must be periodically tested/adjusted as well.  In this photo, the relief valve is to the right, attached to the bronze port on the butterfly valve body.  The relief dump opening is seen underneath it, as a threaded port facing downward.

Built in intake valves often have their own individual relieve valves.  Hale Master Intake and Waterous Monarch, to name two, will likely have these.  They must be tested according to the manufacturers specifications, which will require water being pumped to the intakes from another rig or a testing pump.  In addition, many pumps will have an additional relief valve attached to the suction/intake side of the pump. which needs to be tested.

Whether you test these valves in house, or have a vendor perform the testing, it is critical to have it done at the manufacturer recommended intervals and to follow their procedures.

Do You REALLY Want Them to Learn Something...?

An instructor or company officer has a duty to the student/firefighter in training to assure that the concept being taught is understood.  How do you accomplish this?  In the world of engine company operations, consider that the use of gauges and flow meters may have a MUCH greater impact on learning than trying to sit in a classroom and crunching numbers on notepads.  Check out some of these photos to see how this concept is applied in training evolutions.

The most important thing you must do before you use the equipment is connect with the students/members; a little tailgate talk assures that everyone is on the same page.

A handheld pitot tube is a must have for engine company training

A properly calibrated portable flowmeter goes a long way proving and disproving hydraulic concepts

Want to teach the principle of elevation loss....take a pitot tube into the air and have the operator raise and lower the ladder to show the change in readings

Aerial inlet gauges compared to a pitot or gauge reading at the tip will help show pressure loss in the piping and elevation loss

Using a handheld Pitot to verify wagon pipe flows

A nozzle test rack is a great tool.  To check flows of combination nozzles, inline gauges at the inlet compared to the pump panel gauge will illustrate pressure loss in the hose.  The proof is in seeing it!

A Flow test tube (Fixed Pitot) is a great way to show the performance/limitations of a relay pumping operation

Make idle time a learning time, attaching a gauge to the hydrant will show the water system pressure at different stages of the operation. 

Foam systems with flowmeters are a valuable teaching tool if they are calibrated and understood.  This test was utilizing the front suction, flowing 1035 GPM.

Don't forget the trusty gauge.  See the differences between the main pump gauge and the line gauge.  50 PSI Vs. 120 PSI.  This shows a 70 PSI loss in the rigs piping,  This is flowing to a rear step discharge.

Properly anchored, unmanned deluge sets are one of the safest ways to provide flows and test them during pump operator training.  This reduces the chances of personal injury that are greater when manned hoselines are used.

A deluge set adapted to receive 2 1/2" or 1 3/4" hose is used to teach handline pump pressures.  This eliminates the need for members to man hoselines and be exposed to the potential for injury.  The operators practice pump pressures for either diameter of hose, not both.  The results are checked with a pitot tube, inline gauge or flowmeter.

Evolution and Technology Change the Rules for Length of Foam Lines

I was asked, the other day, whats the longest hose lay you can use when operating with a foam injection system.  This question is born from the use of truck mounted bypass eductor systems, where there was a maximum efficient hose lay to allow the eductor to properly pick up the foam concentrate.  The bypass eductor systems required that the correct nozzle be used and that it be open fully, the correct size/length of hose and maximum elevation limitations to properly function.  It could become quite the balancing act. 

The answer to the question of how long of a hose lay you can have with an injected foam system is pretty much unlimited, with the parameters of the system maximum capacities.

Foam Injection Systems

Hale 3.3 System Capacities

Let's use Hale's Foamlogix as an example.  The system uses a foam pump to inject concentrate into a water/foam manifold, where it then provides that foam solution to the discharges that are supplied by that manifold.  The foam capable discharges will be marked as such on the pump panel.  Its also important to remember that the foam system capacity is cumulative for all of the foam capable discharges.  Before we proceed, lets take a look at the maximum capacities of a 3.3 Foamlogix system.

By the data supplied on this plate, we can deduct two important things that relate to total water flow (with foam) capability.  The maximum working pressure of 400 PSI and maximum water flow of 1250 GPM are the two major factors that lead us to the answer of how far we can pump the foam. FoamPro lists similar capacities below.

FoamPro Specs-Courtesy FoamPro

Courtesy of Hale

The other information we need to know is what is the maximum water/foam flow at each percentage.  because the foam pump can only supply 3.3 GPM of concentrate, there are limitations on the total flow it can produce.  For this 3.3 model system, the chart to the right shows the maximum water flow for the chosen foam percentage.  To accomplish this, the system meters water flow and communicates with the foam pump to meter the appropriate amount of concentrate to maintain the foam percentage.  As a sidebar, the best way to take advantage of the capabilities and limitations of a foam injection system when using class B foam is to use lower percentage foam (higher concentration).  1% or 1%/3% foam provides the capability for higher total water flow.  Compare the differences between the 3.3 and 5.0 systems.  The 5.0 system uses a 5 GPM foam pump.

A Bit About Eductors

A simple 125 GPM inline eductor.

 Anyone who's used a truck mounted bypass eductor system will remember the rule of no more than 150ft of hose, or in some cases 200'.  These distances also apply when using portable foam eductors.  Many departments also used red hose on that foam crosslay/preconnect, to make it more apparent that it was the foam line.  Lets take a step back and see where the old distance rules came from.

Most eductors require 200 PSI at the inlet in order to properly create the foam.  The flow of water through a small orafice in the eductor into a larger chamber within it results in a low pressure zone, which draws foam concentrate up the pickup tube and mixes it into the water stream.  The proper pickup of foam concentrate is also influenced by backpressure on the eductor.

Backpressure can be caused by;

• Pressure (friction) loss in the hose.  The distance you can pump beyond the eductor is based largely on the water flow.  This is where basic hydraulics comes back into play.
• The nozzle.  The nozzle creates backpressure by design, this is how we create a useful fire stream.  A nozzle, not opened all the way will create too much backpressure, reducing the efficiency of the foam operation
• Elevation.  Head pressure will create backpressure that will deteriorate the foam operation.

Eductors can use about 65 percent of the inlet pressure on the outlet side.  What this translates to is a maximum discharge pressure of 130 PSI  on the outlet of the eductor before the foam concentrate flow is compromised.  Using an inline gauge on the outlet of the eductor can monitor this, but the information is easy to figure out beforehand.  If you consider the maximum outlet pressure from the eductor is like a maximum pump pressure, then the following chart illustrates the maximum hose lays when using eductors.

Courtesy Akron Brass Corp.

You may note the 150' and 200' hose lays in the first column, when used with 3%/6% concentrate, as it was one of the most common types of ATC/AR foam types used.  Confusing, maybe a little, but planning ahead of time and marking the pump panel can eliminate any confusion.

Tying it Together

Does it seem like we went way off tangent? Perhaps, but it provides the basis from which we got the old rule of thumb for the maximum hose lay with foam systems.  Now that we are seeing more foam injection systems, this hose lay rule doesn't apply the same way, because the required balance of hose length, nozzle, elevation isn't at all similar.  We previously mentioned the maximum capabilities of a Hale system.  Lets see how that translates to real world terms.

If the maximum pressure of the system is 400 PSI, and we are operating a 100 PSI nozzle, we can use the remaining 300 PSI to account for pressure loss in the hose and any elevation loss.  Keep in mind, 400 PSI is an extreme pump pressure, and it might be more realistic to shoot for a maximum pressure lower than this.  Factoring your maximum hose length is probably better done at a maximum of 250 PSI, as any pressure in a hoseline greater than that will be arguably dangerous and difficult to manage (very rigid) when the water is not flowing.  The point here, is to illustrate how to deduct the maximum working length of a hose line when using an injected foam system.  Using the maximum capacity of the system (400 PSI) we can determine the following;

• A 95 GPM foam line can be run about 2100 feet, using a 100 PSI nozzle.  The system capacities will limit the maximum foam percentage to 3% at 110 GPM, so for round numbers (since 95 and 110 are pretty close) your 3% foam can be pumped about 2100 feet in 1 3/4" Hose.  If we switched to 2" hose, the distance increases to 4200 feet.  Using 1 1/2" hose, the maximum distance is 1350 feet.  If your nozzle is a low pressure fog or smooth bore (50 or 75 PSI tip pressure, the distance will be greater).

To arrive at the answer to this question, when using a foam injection system, consider this simple formula;

MD=MSP-NP-FL-EL

MD is Maximum distance

MSP is Maximum System Pressure (Replace with 250 PSI for more realistic flows)

NP is nozzle pressure

FL is fricton loss (for the flow you have chosen)

EL is elevation loss

To truly know the maximum distance, you should consider the maximum flow you will use at each percentage of foam (typically .5, 1, 3 and 6%) and find the friction loss value on a chart to insert that number into the equation.  Because most nozzles are set to predetermined flows (except for automatic nozzles), using predetermined friction loss values for flows such as  95, 125, 150, 180, 200 GPM makes that part of the equation easy to determine.  You will just need to verify your desired flow is within the range of the foam system.

The short and scientific answer here is....

You can go WAY FURTHER than 150 or 200 feet from the rig when using an injected foam system!

Apparatus mounted bypass eductor systems are still an option today, but they limit your foam flow to one discharge and also have top end flow restrictions that are lower than larger injection pump systems.  Understanding the system you have is critical, before you can determine how to best utilize it.

Read the owners manual for your foam system to learn its capabilities.  Links to major manufacturers are below.

Akron: www.akronbrass.com

Hale: www.haleproducts.com

FoamPro: www.foampro.com

Waterous: www.waterousco.com

Pierce: www.pierceparts.com or www.piercemfg.com

Managing the Transition...

Making the transition from operating off the booster tank on your rig to receiving a supply from a pressurized source; such as a hydrant or nurse tanker, can be a careful balancing act. Preventing over pressure to the attack lines is possible with proper technique and equipment, but there is one situation where pressure relief protection will not work.

The two primary means to control the desired discharge pressure during the transition are the discharge relief valve and the electronic pressure governor.

A Hale TPM Model Discharge Relief Valve Control

Discharge relief valves monitor pressure on the discharge side of the pump by use of a pilot valve/sensing chamber. When the hand wheel or crank is set, any spike in pressure causes the actual valve to open, resulting in the flow of water back to the intake manifold in the pump or dumping it to the ground. This is how the system attempts to relieve the over pressure condition. Discharge relief valves require a differential between intake and discharge pressures. This differential can be from about 25-50 PSI. At high flows, it is possible to overtake the relief capacity of a discharge relief valve.

Many new rigs come with electronic pressure governors, which work well when functioning within their design parameters. These devices use a pressure sensor ( transducer) on the discharge side of the main pump to adjust engine throttle, thereby maintaining the desired pump pressure. This is accomplished in the "PSI" or "pressure" mode. When the sensor detects the increasing pressure as you open the intake, it will progressively ramp the engine down until it reaches idle. Herein lies the problem.



Fire Research Electronic Pressure Governor



Many departments run smooth bore or low pressure nozzles. These nozzles, coupled with high performance attack hose can result in pump pressures below 100 psi. For example, a 200' 2" preconnect with a 15/16" tip will have a pump pressure of approx 90 PSI. If the incoming pressure is over 90 PSI, the governor cannot lower the engine RPM enough to alleviate the pressure surge. Correspondingly, there fails to exist enough differential between pressures for a standard discharge relief valve to work. In fact, since the discharge pressure is lower than the intake pressure, neither pressure protection device will work, and the line(s) will be over pressurized, unless you anticipate and take additional action.

In the example we just reviewed, you must prepare to gate back the discharge(s) as you make the transition. With a situation where incoming pressure is higher than outgoing pressure, there is no other way to deal with the over pressure to the line(s).

You have little control over this when operating from hydrants, but you do if operating from tanker nurse. The best option is to have the tanker driver start pumping to you at 50 PSI when being nurse fed.

As you can see, having an extra hand can be necessary. You must prepare to gate back the discharges when making the transition in the event the pressure protection devices cannot work as intended. As a final note, always make the transition SLOWLY!

Stay Sharp on the Highways

Complacency on the highways is commonplace, watch these videos for some refreshers on the dangers and how to protect yourselves

Electrical Safety-Videos

take a look at the following videos for some insight on fireground electrical safety. 

We deal with electrical issues on a routine basis, stay aware and be safe

Fire Sprinkler Systems-Overview

Here is a short video that reviews the basic principles of wet and dry fire sprinkler systems.  While somewhat dry, understanding these systems is critical.

How many runs do you go on that involve automatic alarms and sprinklers?

Stay tuned for additional articles and videos discussing suppression systems.

Communications Drill-With Video

If you ever need to do a drill that doesn't require alot of preparation and is simple to conduct, can be done indoors and has a positive impact on your members, this might be a concept to consider.

The drill can be conducted using a number of principles.  We chose to do C.A.N. reports, MAYDAY messages and L.U.N.A.R. Reports, with the emphasis strictly on clear and effective communications.  To add realism and reinforce the need for brief and clear messages, we will create realistic background noises and distractions.  Some ideas for these distractions include, but are not limited to;

• Smoke alarm activating
• Low air alarm sounding
• Power saw operating
• Member striking Halligan with sledge or axe (simulate forcible entry)
• Water flowing from nozzle and striking walls and ceilings or ground nearby
• Vent Fan blowing air
• PASS Alarm activated
• Recorded fireground audio clips played at heightened volume (YouTube)
• Pump engaged at high RPM

The noises are intended to be characteristic of actual fireground chaos and sounds.  However you accomplish this isn't as relevant as the idea that you need to create something legitimate and effective.


Two to four members will go during each evolution.  One member will act as the "officer/IC" while one will operate as the firefighter or officer issuing the radio report(s).  An additional firefighter or two may need to assist with creating the background distractions.  Members who will be issuing the report need fire gloves, a radio (worn in whatever manner they will wear it during firefighting operations) and an SCBA with mask.

Preparation for the drill is fairly simple and includes the following;

• Create "Scenario Cards" which will give the member issuing the report some basic information on the situation they are in.  Make sure the info is brief but includes anything that would be pertinent to the type of report they are going to give.  The cards are not intended to be read, but rather to create a mental image.  You may opt to include a photo as well, of an actual incident/situation.
• Set up the area where the report will be issued from.  Whatever you intend to use to create the different noises must be set up in this location.  Based on the variety of options, the location you choose may be anything from an office with a computer you can play audio footage to the outside wall of the firehouse where you might opt to spray a hose stream to make noise.
• Have the member giving the report don the SCBA and Mask and report to the location
• Provide the "officer" that will receive the report with a notepad and pen along with a radio.
• Assure the radio is operating on a private/non-emergency channel.  If any doubt exists, notify your communications center at the start and end of the drill that you are doing training and advise what channel is being used.
• Initiate the exercise, and if possible, record the radio traffic to replay for both members to listen to and confer about afterwards.
• After the "IC/Officer" indicates that the report is understood and has verified it with the other member, terminate the evolution and bring everyone in to discuss the exchange.  Play the audio back first, before any discussion.  Discuss the length of time it takes for the report(s).

The scenario cards are intended to give a brief, bullet point overview.  Not to be read over the radio

Acronym cheat sheets are good for the first few runs, but take them away later in the drill

The drill will conclude when the two members participating feel that the report is understood between themselves.  The end goal is a very brief transaction.  Expect there to be hiccups and speed bumps in the beginning.  Practice the scenarios over and over. Discuss the elements of the different reports you are covering.  Assure that everyone understands the intent of each evolution.  Members may find that they need to adjust how they carry their radios, how they talk (volume, rate) or how they try to explain it.

This is just another company drill idea, it has a lot of flexibility and allows you to craft scenarios that are based on situations your company would encounter.  It fosters radio confidence, strengthens communications skills and gives the participants the opportunity to experience the situation being simulated in a controlled but fairly realistic environment.

Stay safe and train often and realistically!

TFT Nozzle Test

Video from a nozzle test we did today

Isn't Your Life Worth More Than a Stupid Candy Bar Wrapper?

When you choose a nozzle, many factors go into this critical decision, or at least they should.

One major manufacturer of nozzles offers an option to prevent debris from fouling their automatic nozzle tips.  The screen that they offer, is typically found at the nozzle inlet, behind the bale.  In the break-apart models it is located at the inlet of the fog tip, ahead of the bale.  the screen prevents larger debris that cannot be passed through the nozzle on the flush setting from fouling the nozzle.  Theres a catch though....we have vandals on the prowl....



this kid has too much free time, so he thinks it would be funny to stick a candy bar wrapper in the standpipe outlet.  Here, we use the gated wye attached to a flow tube, it serves the purpose just as well.



The water flows, at 162 GPM.  A nice stream forms at the nozzle, if you bleed your nozzle too quick, you'll never know whats about to happen as you step over the threshold of the door to the fire floor.

...and then, boom, catastrophic failure of the stream.  This is from, a stupid candy bar wrapper....that's it.

The nozzleman is armed with a breakapart automatic nozzle, the smooth bore slug tip is 15/16"  He is quick to see the potential issue and you see the result above.

Is this possibility realistic?  You tell me?

Another test shows that trying the flush doesn't have any effect.

Don't die for a candy bar wrapper, buy the right equipment and know how the equipment you have works.  This nozzle works very well, if you use it properly in the right applications.

Thanks to the Richmond, Virginia Fire Department for planting the seed that led to this experiment.  Oddly, our nozzleman just happens to be wearing one of their hats!

Standpipes and Gated Wyes

Today, we conducted a brief experiment to determine the pressure loss in a 2 1/2" x 1 1/2" gated wye when the use of 2 1/2" hose is desired. A 20' section of 2 1/2" hose was attached to the flow tube on the fire hydrant. We used adapters in place of a bushing on the outlet of the wye with the following results;

With gated wye. 1 1/8" tip, 250 GPM. The flow was verified with a flow meter and handheld pitot gauge. Pressure at hydrant was 83 PSI. Tip pressure 50 PSI. Pressure loss was 33 PSI

Without gated wye. Same tip, same flow. Pressure at hydrant was between 48 and 50 PSI with corresponding tip pressure readings, meaning the pressure loss was negligible without the wye.

Assume a loss of 25 to 30 PSI through the valve with a setup like this. As you can see, the old 10 PSI loss is a big underestimate here.

Attack Lines. Crosslay or Hosebed?

A question was posed by one of our readers today regarding the differences in having attack lines located as crosslays versus being in the rear hosebed.  The location of attack lines varies from department to department, and also from apparatus manufacturer to manufacturer.  Lets look at some of the considerations that go into this critical decision.

It seems pretty common to find attack lines located above the pump house in the "crosslay" configuration.  Another common transverse configuration is the "speedlay", which is found located in the walkway of top mount pumpers or through the body of some styles of rigs.  These configurations offer some different options, from width, to piping configuration and in some cases, the hose may even be stored in plastic bins that slide into the chutes.  Available options for these transverse hose loads include piping located inside the hose slot (with the standard swivel connection) as well as piping located on the pump panels just below the hosebed (LA Style).  Piping in the hose slots may be located so that it is under the hose load, or in some cases (speedlays) the swivel connections may be located above the hose loads.




Standard crosslays with pipe connections at the bottom of the load.  This rig has lower than typical height crosslays, which would make it much easier to pull the line.  NFPA requirements for hosebed covers, however, slow down hose depoyment.



These "Speedlays" have plastic bins, so the hose can be loaded outside the rig.  As such, the pipe connections are above the hose, which may cause some difficulty with certain types of hose loads.



With single stack, low crosslays, 4 slots here allow two lines to run off each side.  Pipe connections in the bottom of the slots require the entire line to be preconnected.  If you prefer different length lines, this is a perfect setup to have one of each length off each side.



LA Style.  This design uses a single discharge under the transverse beds on each side.  The connection is on the panel, not in the slot.  This allows the transverse beds to be used more like traditional hose beds.  Some departments use an appliance on this discharge, some have several discharges located on each side.

Crosslay and speedlay hose locations and configurations can be slaves to other pump and apparatus features.  When you specify certain pump and valve features, the pump house must be a certain size, which may cause issues with height and capacity of crosslay slots.  Most manufacturers build standard hose slots for 200 foot crosslays, because that seems to be the typical amount of hose carried.  At specification meetings, make sure to make your desired hose slot height and capacity known.  Additionally, the type of hose load used may factor in.  If using a minuteman, for example, you may want a single stack slot or a dual stack slot.  Either way, you need to know and state this when you work through the specification process.
Some advantages of crosslay/transverse hose loads?

• They are quick to deploy
• They are pre-engineered and standard features on rigs
• They are a better place to put attack lines on rigs that have high hosebeds or aerial/quints with limited hosebeds.
• When you are using pipe connections on the panels, versus in the hose slot, they offer similar flexibility to rear hosebeds.
• The length of a crosslay bed makes the hose load the right size for shouldering, as it is typically no more than 8' long.

Some disadvantages of crosslay/transverse hose loads.

• Hose capacity may be limited due to apparatus design
• Height of crosslays may be extreme due to pump house and other apparatus design issues
• Hose will often be in the operators working area (many times near their head) when in service
• When pipe connections are in the bed, the entire load must be preconnected, meaning you cannot store dead load hose under the preconnect to extend the line.
• Piping runs may necessitate the use of several elbows, resulting in high friction loss
• Many times, crosslays are so high, grabbing and deploying them is almost dangerous.

In our firehouse, the height of crosslays on two of the rigs is between 76" and 77" to the hose bed floor.

Don't forget the pigtail!.  If you want the flexibility of being able to break and extend crosslay lines or disconnect to repack, a pigtail section of hose from the swivel to the ground is a great idea.  The length will be determined by the height of your hosebed.  We use 10' lengths.  Its a good idea to use a bright, different color hose to also visually indicate the attack line is fully deployed.

Preconnect pigtail, with nozzle and gauge attached during a flow test to determine piping friction loss.

You can see the bight blue pigtail in the background as well in the drivers hands.  This allowed a 200' line to be extended with a donut roll in about 40 seconds.  Had the connection been in the bed it would have been much harder.

Now, onto rear hosebeds.  This option is somewhat "old school", as its where hose was usually stored on the first motorized fire apparatus.  Rear hosebed attack line storage went out of favor with the dawn of the crosslay (Mattydale to some).  Some departments never changed the way they stored and deployed their hose, because...well...it worked.  Working off the rear bed usually adds more flexibility when your rigs are able to have a hose bed height that's within reachable distance from the ground.  On rigs with large water tanks and rescue bodies, hose beds are forced to be raised to accommodate those body features, and storage of attack lines may be more favorable as crosslays or even up in the bumper.

A Firefighter, standing at 5'7" easily reaches this rear attack line, with a 61" Hosebed floor.  The 400' line is ideal for apartments and long setbacks.  The hose connection is at the tailboard, allowing this line to be broken at any length and utilized.

Rear hosebed attack lines are typically loaded into slots in the hosebed.  There are a few factors to consider with rear hosebeds.

• How high is the hosebed?  Does the hosebed floor height lend itself to ease of attack line loading and deployment?  Some rigs must have a high hosebed to accommodate tanks, ladders or compartments.  This may make them unfavorable for attack lines.
• How deep is the hosebed?  A shallow hosebed will require hose to be stacked higher, and may make reaching the top of the hose load difficult.  A long/deep bed will cause the hose to be too long to shoulder load, and result in it dragging on the ground.  Hose beds for attack lines should be no greater than 8 feet deep.  This gives you 4 feet of hose in front and behind you, if you shoulder the load.

When you decide to use the rear hosebed for attack lines, you also need to decide if you want the discharges in the bed (at the front of the hosebed) or at the tailboard, outside the bed.  Its much easier and more versatile to locate the discharges at the tailboard.  This allows you to break and extend the line, stretch short etc.  It also allows you to carry additional hose, static or dead loaded under the preconnect.
 

Discharge at the tailboard.  This configuration also allows additional dead load hose to be kept under the preconnect.  This slot has 400' of 1 3/4", with 250' preconnected.



Make sure the dividers for the rear hose beds are the proper size.  Dividers that are too tall will make repacking the hose nearly impossible.  These dividers are sized just right.

This rig has a nice large tailboard, with attack lines off the rear.  It is well suited for the tasks of an engine company.

This squad companty has a rescue body design, which does not make the rear hosebed favorable for attack lines.  They overcame this with four very low "LA" style crosslays

Does the water tank have anything to do with it?  Sure it does.  An "L" tank will lower the hosebed floor.  "L" tanks are available in both rectangular and "T" styles.  The "L" shape is determined by the side view.  The "T" by looking at the front or back.  Our rig has an "L" shaped "T" tank to allow for the standard pumper body configuration with a low hosebed.

Specification language used when we built our rig for the hosebed reads as follows:

6.18 HOSE BED

 

The hose bed floor shall be a no more than 60” from ground level.  It shall be no deeper than 8 feet.  This shall be accomplished utilizing an L shaped type water tank.

The hose bed shall be provided with aluminum slatted flooring radiused at the edges to prevent hose damage from sharp edges.  Each hose bed floor section shall be removable for easy access to the water tank.

The tank in our rig is "T" shaped, looking at it from the rear, but it is an 'L" tank to facilitate a lower hosebed.

Some final points to ponder, regarding the hose and nozzles.  Hose varies in dimension by brand and model.  The difference in how hose is manufacturered means you may only fit 150 feet of brand A hose in your slot and 250 feet of brand B.  Get your hands on samples, see how it packs, deploys and performs.  Ask departments that are using hose alot what they have.  Nozzles are another factor.  Your hose bed slots, particularly for crosslays, need to account for the nozzles you choose.  Remember, certain hose loads like a minuteman will not allow the nozzle to pass the opposite direction than how it is loaded.  Pistol grips may also create issues in narrow hose slots.  Make sure there is space for them.  There is nothing worse than having your new rig show up and finding out you can't pack your hose into the attack line slots like you wanted because of a manufacturing issue.  In the end, it is most likely the failure to plan that results in such an occurrence.

We didn't talk about it here, but remember, front bumpers aren't just for trash lines.  Preconnects of up to 200 feet can easily be stored in front bumper wells.  On many engines, otherwise unused bumper space can make way for additional hose wells, offering two attack lines up front, down low and still leaving space for a front intake and soft sleeve.

Your goal, with attack lines, should be to have a setup that is designed with the following key points in mind;

• Safety.  can your firefighters reach and deploy the lines without climbing up on the rig?  If they have to climb, is the stepping surface such that they can climb and deploy the hose without assistance and maintain balance?
• Ease.  How easy can you pack and deploy the lines?
• Flexibility and Efficiency.  How much hose do you have? how is it packed?  Is it good for your first due district?  What about your second due districts?  Is it adaptable?  Can you extend and stretch shorter than the preconnected length?

The unfortunate reality is that many times, the hosebed design, and location of attack lines is determined by the salesman, because the end user hasn't told them otherwise.  In many cases, more thought should go into this critical aspect of an engine.  The truth is, we dertermined our hosebed height by measuring to the shoulder height of an average sized firefighter.  The final result came in one inch higher than we desired.  Can't complain too much about that!

Stay safe, think critically and train hard.

M.G.