Handline Training Tips-Length and Diameter Considerations.

There are many things to consider when drilling on the stretching, advancing and operation of attack hoselines.  Here are a few pointers to aid in achieving realistic results with regard to the length of the hose being used during drills.

Hose length is often not even considered in drills, and often the length of the hoses used is relative to the amount of anticipated cleanup.  In many instances, 1 or 2 lengths is considered sufficient for drills in the parking lot when reviewing hose handling techniques and such.  In reality, you can actually suffer negative consequences running shorter lines for training.  Fire departments need to be realistic in training by using the hose lengths that would commonly be used at a fire.  If you drill with only 1 or 2 lengths of hose to avoid having to clean up more equipment, etc, you could end up suffering from complications.  The example below will use true diameter 1 3/4" hose with a standard coefficient of 15.5.

EXAMPLE 1:  200 foot attack line with a 7/8" smooth bore nozzle.  Pump pressure (PDP) of around 130 PSI - using theoretical numbers.  Reduce the hose length to 100 feet and the PDP drops to 90 PSI

You can see how much the pump pressure drops by subtracting 100 feet of hose in the above example, but why is that a problem?  Some would say keeping pump pressures low is a good idea. Is it though?

We have a dirty little secret in the industry that fire hose is no longer being sold as true diameter, in fact much of it has "creeped" up in internal diameter over the last decade or so as a result of competition among manufacturers.  The resultant effect are hoses with drastic differences in internal diameter and coefficients, causing havoc on our normal PDP and FL formulas.  This can negatively impact hose training.

Do you know the true diameter and coefficient of your hose?

Lets look at the example from before and apply a coefficient for "fat hose" to see how it impacts the equation.  We will use the coefficient 10.22, for a hose that is considered 1 3/4" but sizes in at closer to 1.81" inside diameter.

EXAMPLE 2: 200 foot attack line with 7/8" smooth bore nozzle.  Pump pressure (PDP) of 102 PSI.  Reduce the length of the hose to 100 feet and the PDP drops to 75 PSI

The lower pump pressure brings two factors into play, one is the backpressure at the nozzle inlet and the second is the ability of the pump governor or relief valve to function properly.

Lets look at the nozzle back pressure issue.  The back pressure is created by the pressure within the hose as its restricted by the nozzle orifice.  If you follow the old rule that the nozzle shall not be larger than 1/2 the diameter of the hoseline, you will have addressed one issue that contributes to acceptable back pressure and reduced the propensity of the hose to suffer from what we call "whip," a condition often influenced by low back pressure and a soft hose at the nozzle inlet.

Line gauges at the nozzle inlet will always read low, as they show sidewall pressure, not nozzle flow pressure (stream velocity).  They can give some information, but flowmeters and pitot gauges are the best way to assure accurate flow.  The line gauge will also not decipher a mismatched nozzle to hose, but may show even lower readings as the tip size increases past the 1/2 diameter rule.

In example 1 there was 80 PSI of pressure loss in the hose.  This helps stiffen the hose up a bit, can aid in reducing kinks and helps to build some backpressure at the nozzle inlet.  When the length was dropped to 100 feet in example 1, the pressure loss was dropped to 40 PSI.  You would start to see that the hose might be a bit softer, slightly more kink prone and may start to experience unfavorable handling at the nozzle.

In example 2, things get worse.  The "fat hose" drops the pressure loss significantly, making it notably less.  in a 200 foot length the pressure loss is 52PSI.  By reducing the hose line to 100 feet, the pressure loss drops to 26 PSI.  These drastic differences will translate to handling issues, and to low pump pressures.

The issue of low PDP can complicate the pump operators job as well.  Most single stage pumps will produce around 30-50 PSI at idle, and will amplify that when a pressurized source is introduced (hydrant).  The "net pump pressure" can end up being 125-150 PSI if your fire hydrants are good performers.  This means that the pump pressure control device (electronic governor -aka EPG or relief valve) will be unable to operate as designed.  The unusually low pressures required to supply effective streams to unusually short handlines means that the operator must become the pressure governor, by gating the discharges, essentially eliminating discharge pressure protection until such a time as the discharge flow increases enough for the engine to require additional throttle.  Remember that if your discharge pressure is lower than intake pressure, that the relief or pressure control device will be unable to operate properly.  It is generally desirable to have a cushion of pressure between intake and discharge pressure to allow the pressure relief/control device to function.  If the net pressure is at 125 PSI with the motor idling and the required PDP for the attack like is only 75 PSI, the discharge will require gating to control the flow/pressure and the pressure control device will be incapable of operating properly.

Lets look at example 2, because it uses numbers that are in line with modern hose.  With a short length line (100 feet) and a pump pressure of 75 PSI to support the 160 GPM stream, we know that we need the engine to throttle up a bit when operating from booster tank water.  With the pump engaged, and a static pressure of around 50 PSI, we still need an additional 25 PSI or so.  The EPG will throttle up in the pressure mode, or the operator would throttle up if the pump was equipped with a manual throttle and discharge relief valve.  This works out perfectly well when we are supporting the line from tank water, but things change a bit when we introduce pressure from an external source.

With the pump operating at 75 PSI discharge pressure, we know we are a bit above idle.  Now we would prepare for the changeover to pressurized source.  This is often in the form of opening the intake line from a hydrant, but could also be from a nurse tanker/engine etc.  If we knew that the pump was producing around 50 PSI at idle, and we introduce an additional 50 PSI from an external source, the EPG will automatically see that spike in discharge pressure and lower the throttle.  If operating with discharge relief valve, it would open as the pressure rose over 75 PSI.  In both instances, though, the pressure being discharged to the handline will end up being higher than the pressure coming in, rendering either style pressure control device useless, and requiring intervention by the operator.

To support a 160 GPM 1 3/4" stream, this pump is operating at near idle (900 RPM) and discharging approx 110 PSI.  Fat hose contributes to the low pump pressure.  There is virtually no discharge protection available in this situation.

With the operation of the discharge relief valve and EPG in mind, its fair to say that you actually want some friction loss.  You need some throttle to get the pump up above idle for these devices to work.  Without throttle, you sit at idle, and all pressure changes must be regulated by the operator by gating the lines manually.  It is worth noting that in some locations, water systems are so strong that you're left without the options suggested in this article.  In such instances, diligence to maintain pressures must be exercised by the pump operator.

When you are conducting pump operator training, this issue can come into play as well.  In order to simulate the restriction imposed by pressure loss in hose, it may be necessary to gate the pump discharge valve back and use the throttle to overcome the restriction to ultimately achieve the proper nozzle pressure.  This action may result in broken streams, which can be rectified by attaching stream shapers to the nozzles for training purposes.

You would never pump a hoseline thats supplying a stream at its tip pressure, but when attaching nozzles to the pump thats exactly what happens in most instances.  This can result in the creation of poor habits by pump operator candidates and unrealistic pump pressures that lead the issues discussed in the previous section.

Lastly, its important to understand just how much of a consequence that extra pressure has on the nozzle.  If we stick to the 7/8" tip in the previous examples, the reaction force at 50 PSI is 60Lbs.  This is easy for one ff to manage;  an additional 10 PSI on the nozzle will raise that reaction to 72Lbs (at 60 PSi tip pressure),  If the nozzle is pumped 20 PSI "hot" (70 PSI tip) the reaction jumps to 84 Lbs.  That extra pressure the pressure control device cannot handle during the changeover will translate to extra nozzle reaction, and may cause loss of control or force the nozzleman to gate back.  If using automatic nozzles, additional flow will result, but at the cost of additional reaction forces also.

.Here are a few tips to aid in better handline drills.

• Use the attack hose and nozzles you'd be deploying for actual fire attack
• Use the length of hose that you'd be stretching and operating.  This could vary greatly, but you should regularly train on these lengths.  Generally less than 150 feet may lead to issues.
• Try to maintain the 1/2 nozzle orifice to hose diameter rule, but remember that the rule changes with fat hose.  Knowing the true ID of your hose means that you can usually increase one tip size for certain models of "1 3/4" hose, as their internal diameter may creep up to nearly 2" ID.
• If you use line gauges, understand that they read sidewall pressure and will have an error margin of anywhere from 5-10 PSI on average (lower than stream pressure)
• If you are using nozzles attached to pump outlets to train pump operators, gate the discharge valves back to simularte the restriction imposed by the absent pressure loss in the hose.
• Note the pressure your pumps produce at idle and know what that pressure will increase to (net pump pressure) when connected to a hydrant
• If you can use pitor gauges and/or calibrated flowmeters, they will often be the best measuring tools.

Like all training, its important to train as you'd work in the real world.  Hopefully this article illustrates some points which will help prevent problems in your future drills.

-MG

Heavy Water Hookup - What are your Best Connections for Maximum Flow?

When you need a ton of water for large fires, connecting to the hydrant becomes a critical task and it must be done in such a way that you can take advantage of the water that is available. Before we get into the meat and potatoes of this article, its important that you understand the capability of your water systems.  Water main sizes, system pressures, system age, and fire hydrant barrel and connection sizes are all contributing factors.  In some instances, the information below simply wont be possible for some communities, but for many others it is quite possible.

The "heavy water hookup" is something I think I first remember seeing in the late 90's when Paul Shapiro was making big waves in the fire service.  His relentless pursuit of seeking ways to move volumes of water became infectious and were features at the former "First Due Fire&Rescue" conference in Las Vegas one year when I attended.  The concept isn't new, its simply rooted in the idea that we must be able to take full advantage of the water system when it counts.

Its also important to mention the hardware used when making the connections.  There are many different brands of valves and adapters on the market, and I will illustrate a few here.

Three of the most common styles of 2 1/2" valves on the market

These popular LDH gate valves used on pumper intakes are still being manufactured today.  The 3.5" waterway is a major choke point when attempting to move high GPM

The waterway diameter of various ball and gate valves can be significantly different.  Using gate valves, such as the one pictured on the left usually provide a larger waterway and better. safer control of flows.

These ball style valves are nice, as they offer a locking feature but will not work with LDH adapters unless an elbow is used.

The elbow adapter will allow you to utilize valves if your budget will not support upgrading to gate valves

This style of ball valve also will not work with LDH adapters, unless an elbow is used.  These are less desirable because they have no locking handle and you create the risk of undesirable water hammer if the valve either vibrates closed or is opened or closed too fast.

These gate valves with "rigid" style female  threaded by Storz adapters.  These style adapters reduce the length of the adapter and help reduce the "leverage" effect of the hose on the smaller hydrant outlets by keeping the larger and heavier LDH closer to the hydrant outlet.

The adapter on the left is a "rocker lug swivel" x Storz model, which has a variety of other uses.  While it works on the hydrant it adds a few extra inches of profile and can increase the stress of the hose on the hydrant outlets

This Hydrant is fed from 3 directions on a 16" water main.  Preplanning identifies strong water sources

Another point to consider is the strength and capability of your pumpers.  There are a variety of factors that contribute to the ability of the pumper to provide high flows.  Some of those ingredients include the pump rating, intake plumbing size and piping run, discharge size(s) and piping run and motor power.  Intake and discharge valve waterway diameters are also potential restriction points.  You will need to evaluate your rigs for all of these factors and conduct tests to see what its truest potential is when moving high volumes of water.  For example, I have witnessed a pumper with a 1500 GPM rated, large body pump provide a flow of 3250 GPM with three 5" supply lines fed from two water sources as well as a 1250 Rated pump providing a flow of 2200 GPM from a single hydrant with three LDH supply lines.  How you make the connections and all of the aforementioned factors will influence your top end results.

This 1500 GPM rated pumper supplied two aerial streams, its wagon pipe and a portable deluge gun for a total of 3250 GPM

This 1250 Rated pumper is flowing 2200 GPM from a dead end main fire hydrant

The end goal is to see what the most water you can flow is from your strong hydrants so that when the time comes for high flows you aren't shortchanging your operation or underestimating your rigs capabilities.  Once you have data about your water system you can get a good idea what you might be capable of flowing.  It has been my experience that water mains 12" and larger are easily capable of flows in the 2000+ GPM range.  In our region we do not have a "high pressure" water system.  My experience with hydrants are on a system where static pressure varies from 50-100 PSI depending on where you are in the area.  Water mains ranging from 4"-60" are present throughout the system we operate off of.  You should also consult your local water utility company to discuss water system strength and capability.

We have covered a lot about the water system, adapters and appliances and pump capabilities, now, lets look at actually making the connections to the rig and flowing water.  Over the past few weeks I conducted several tests with some help from fellow firefighters to compare available water flow with various hose connections.  The test pumper is a 1998 E-One with 2500 GPM rated Hale 8FG pump.  The pump has an 8" custom intake manifold and 6" custom discharge manifold for the LDH discharges.  Water was fed to the pump using the front bumper intake, which is 5" piping throughout, Hale MIV intake valves and/or 2 1/2" auxiliary suction connections.  For each test I will explain the exact configuration.  The water was discharged through two 4" LDH discharges, each with 4" valve and piping.  The flows were measured using paddle wheel style flow sensors installed in the 4" stainless piping.  The fire hydrant used for testing is a Mueller 2014 Centurion model on a 1969 vintage water main.  The hydrant is fed from 3 directions.  It sits on a 16" main and a 12" main feeds from another direction.  The Hydrant to main connection is 6" pipe and valve.

One important point to note is the age old argument that a front intake is not an acceptable connection for high volume water flow.  These tests shed some interesting light on that argument.

The Tests

For all of the tests listed, the hydrant had a static pressure of 80 PSI as read on the pump panel compound gauge and the test results were measured when the compound gauge reached 20 PSI.  We could have obtained additional flow by taking the compound to 10 PSI but chose to limit it at 20 PSI.  The flowmeters had some slight "drift" so the numbers recorded were about the average of what amounted to about a 25-50 gallon per minute variation due to some expected turbulence.

Test 1.
25FT 5" LDH from 4 1/2" Hydrant connection to front intake
2050 GPM
Notes.  This is a phenomenal amount of water and really illustrates the potential capability of a front intake.

Test 2.
25FT 5" LDH from 4 1/2" Hydrant connection to front intake
25FT 5" LDH from one 2 1/2" hydrant outlet to drivers side MIV (6" Inlet)
2760 GPM

Test 3.
25FT 5" LDH from 4 1/2" Hydrant connection to front intake
25FT 5" LDH from one 2 1/2" hydrant outlet to drivers side MIV (6" Inlet)
50FT 5" LDH from other 2 1/2" hydrant outlet to officers side MIV (6" Inlet)
2950 GPM

Test 4.
25FT 5" LDH from 4 1/2" Hydrant connection to front intake
50FT 3" from one 2 1/2" hydrant outlet to drivers side auxiliary suction ( 2 1/2"" Inlet)
50FT 3" from other 2 1/2" hydrant outlet to officers side auxiliary suction (2 1/2"" Inlet)
2700 GPM

Test 5.
50FT 3" from one 2 1/2" Hydrant outlet to drivers side auxiliary suction (2 1/2" inlet)
825 GPM

Test 6.
25FT 5" LDH from one 2 1/2" hydrant outlet to drivers side MIV (6" Inlet)
1600 GPM
Notes.  This is almost double the flow when compared to the equal length of 3"

Test 7.
50FT 5" LDH from one 2 1/2" hydrant outlet to officers side MIV (6" Inlet)
1500 GPM
Notes.  This is a 100 GPM decrease from Test 6 by adding 50 extra feet of hose.

Test 8.
25FT 5" LDH from 4 1/2" Hydrant connection to drivers side MIV (6" Inlet)
2260 GPM

Test 9.
25FT 5" LDH from 4 1/2" Hydrant connection to drivers side MIV (6" Inlet)
25FT 5" LDH from one 2 1/2" hydrant outlet to front intake
2825 GPM

Test 10.
25FT 5" LDH from 4 1/2" Hydrant connection to drivers side MIV (6" Inlet)
25FT 5" LDH from one 2 1/2" hydrant outlet to front intake
50FT 5" LDH from other 2 1/2" hydrant outlet to officers side MIV (6" Inlet)
2860 GPM

Test 11.
25FT 5" LDH from one 2 1/2" hydrant outlet to front intake
1520 GPM
Notes.  This was only 60 GPM less than going to the main pump inlet.

One variation of hookup using LDH

Many FD use this as their best option for maximum flow.  It can limit you by a few hundred GPM.  In these tests it proved to be 250 GPM less than when 5" hose was used.  

In summary, the best results were from test #3, using the front suction as the primary hydrant connection.  There was only a 40 GPM difference when the primary connection was made from the hydrant steamer to the main pump intake vs the front suction. In my assessment of the information, I believe that the final result shows that it didn't seem to matter if the the primary connection was to the front intake or the main pump inlet.  I would, however, be curious to see how a front intake with swivel impacts the results. I believe that when the hydraulics of the water main to hydrant connection (6") are compared to the hose connections to the hydrant there is a way to correlate them.  Unfortunately I am not able to provide any form of calculation to verify that relationship, math was never my best subject!  A single 5" hose connected to the 4 1/2" outlet of the hydrant cannot maximize that 6" main connection, I believe that the addition of a second 5" hose when connected to the  2 1/2" outlet comes close to matching the 6" hydrant to main connection and thus why we saw no major improvement in flow when adding the third 5" hose.

The interesting thing I saw from all of these tests was that there was no significant gain by adding the 3rd 5" hose, but that there was notable improvement in flow when two 5" hoses were used.  It appears that the additional gain from the 3rd 5" hose when connected was between 35 GPM and 190 GPM.

I would conclude that the best practice when operating for large volumes of water is to get at least two 5" lines connected to the hydrant, with three being ideal.  Remember that using shorter lengths helps.  We carry standard LDH lengths of 25, 50 and 100 feet.  When your operators practice spotting the rig you will see where the different lengths of hose fit in best.  Due to the many variables that exist in apparatus piping, the three LDH line connection will assure that where flow resistance is met through one connection that the water can choose the path of least resistance to find the highest potential flow through the connections you have made.

Thank you for reading and following sendthewater.  Please remember that tests such as this are subject to some margin of error and are simply meant to illustrate information within the means available to do so.  It is fair to say the results speak pretty clearly in a relative sense when comparing them to each other.  Individual results WILL vary with all of the previously mentioned variables.

Please comment on our Facebook page with feedback and suggestions.

MG.

Over or Under

When using jet siphon devices to transfer water between dump tanks during water shuttles, the question of where to secure the discharge ends of the jet siphon tubes seems to bring a mixed response.  Should they be secured over or under the water? Here is a brief perspective on their placement. 

 

I believe that securing them over the tank rail and above the water line is the most advantageous option.  This placement provides the following advantages;

• The hard sleeve does not have to be as long to drape between both tanks.
• The open end of the tube is visible so that the quality of the water flow is easily identifiable.
• The operator(s) of the jet siphons can determine which ones are flowing
• The water being discharged does not push strainers on the bottom of the tanks around
• When tanks are on a slope, having the discharge end above the water line is ideal so that when the jet is shut off, water will not flow backwards - in a reverse siphon.  This can accidentally drain water from the main tank if it isn't attended to.

On the con side, having the ends of the tubes at the tank rail requires they be secured.  Rope, webbing or bungee straps all work.  For speed, heavy duty bungee cords or lightweight ratchet belts are worth considering.  The air that's entrained into the dump tank by the discharge of the jet siphon above the water line into the receiving tank has not shown any notable negative impact at any operation I have been involved with. 

 

The quality of water flowing from the far siphon shows air is entrained.  From a distance this tells us the tank level is low and we can expect that this device has or will shorty stop transferring water.

The more laminar looking flow of this siphon shows us that it is operating properly, and is not drawing any air in.  With its discharge end above the rail we can tell its obviously working as expected.

In this 2200 GPM water shuttle, it helps to see the ends of the siphon tubes to know that the flow can be maintained.  in High volume water shuttles, surprises are not good, so being able to monitor each siphon tubes flow is very important.

 

Webbing, rope, or bungee straps can be used to secure the tunes to tank rails. 

 

In this photo, you cannot tell which of the 7 jet siphons is flowing, nor can you tell the quality of water flowing form them.  This operation supported 2500+ GPM, but had two separate control locations for jet siphons.  If the control operators could see the ends of each tube it would make coordination a bit easier.

 

You can see the far siphon indicating flow is lost in the dump tank, as air is entrained.  The near siphon is delivering a significant volume of water still

 

This 2600 GPM water shuttle had siphons above and below the water. 

With regard to jet siphons, a few other things to remember are;

• Pump the siphons at no less than 100 PSI.  125-150 PSI is ideal.
• Provide a dedicated water transfer engine at the dump site, so that total capacity from the supply pumper to the fire is not stolen to "drive" the jet siphons.
• There are many brands of jet siphons with different performances.  Check out an article we did on jet siphon flows;
• http://send-the-water.blogspot.com/2013/10/water-transfer-testing-jet-siphon-flow.html
• Here is an article by GBW Associates at http://www.gotbigwater.com/content/data/file/Jet%20Siphon%20Flowtests.pdf

In conclusion, securing the jet siphon tubes above the tank rail provides several advantages over placing them under the water.  If you haven't already, try it out next time you drill.

Turn it Up! Putting the 100 PSI Pump Pressure Myth to the Test

For many years, as I have taken pump courses, participated in training sessions and taught pump programs I come across a disturbing phenomenon with regard to what pressures pump operators are using when flowing to their handlines.  Many times in the discussions, someone throws out there that they pump the preconnects at 100 PSI and allow the nozzleman to choose to have the pressure increased or decreased upon request.  This "works" for alot of departments, but it doesn't really work well if you consider that an attack hoseline system should be something designed and implemented with alot of different considerations made.  Some of these considerations should include your desired hose diameter, length, type of nozzle, typical staffing, desired maximum nozzle flow and backpressure and more.  It is a decision making process given little to no attention in many fire departments which often results in a terrible mismatch of hose and nozzles and firefighters who struggle to use the end result either because the inadequate water flow cannot extinguish the fire or because they cannot handle the backpressure off the fire stream.

I have been lucky to participate in many good discussions, review alot of good data and obtain alot of my own data about hose and nozzle selection in the past few years.  As I am writing this, I have to admit that 5 years ago, I feel like I knew not even half of what I know now, and I still feel like there's much to learn to evaluate and implement a good combination of hose and nozzles for a functional and effective attack hoseline system.

In this article I want to address the specific issue of under pumping attack lines.  Preconnected attack lines in particular.  There isn't any solid data, nor is there a way to gather it, but I feel pretty confident that many engine companies are under performing in GPM delivery because they haven't put the pieces of the system together and/or done the tests to determine the proper flow of their attack hose/nozzle systems.

The end goal of our tests is a 150 GPM fire stream.  The relative comparisons are meant to see how close we can get to the starting benchmark of 150 GPM with improper and then proper PDP.  I consider the 100 PSI PDP test results failing if they do not meet 150 GPM, and there should be no surprise that they didn't.

I want to make it very clear that the goal here is not to discredit the nozzles.  Each nozzle worked exactly as designed, when it was used properly and pumped properly.  This article is a comparison of three different nozzles being improperly utilized, on purpose, to illustrate the impact it has on total water flow delivery.  I have my preference in nozzles, but that isn't relevant to this piece of work.

Earlier this week I gathered several nozzles to evaluate how they would perform when pumped at the 100 PSI pump discharge pressure (PDP). The three nozzles evaluated were the 50-350 GPM Automatic Task Force Tip, 7/8" smoothbore tip and SM-30 Elkhart Automatic.  With the help of several firefighters we set up a series of tests, while we also conducted testing for our preconnected attack lines.

The test setup was 200 feet of rubber lined double jacket 1 3/4" fire hose.  Test gauge was installed at the front bumper connection, and at the inlet of the nozzle.  There was no elevation and no other influencing factors.  I chose 200', as it represents a very typical length preconnected attack hoseline.  Its important to note that different brands of hose will vary in internal diameter, and different lengths of hose will yield different results.  There are many variables which make the collection of data for your individual department important.  The results we have represent fairly accurate numbers, but I like to say that its not perfect.  The relative differences between each PDP for the given nozzle are the most important part of this comparison.

The hose we used has a known internal diameter of 1.81" per the manufacturer.  The hose was connected to the front bumper discharge of the rig, which is a typical connection for our fire department operations and represents what I feel is a realistic amount of plumbing loss.  When utilizing a crosslay with swivel, it is typical to have at least two 90 degree bends in the piping.  The rig used was found to have approx 10-15 PSI of loss in the piping to this discharge at 150 GPM.

The three nozzles tested were the second third and fourth from the left

Once the hose was laid out and the gauges installed, the testing commenced.  The rig was connected to a hydrant via 25' front soft sleeve.  The hydrant pressure and flow were greater than necessary for the low volume testing.  Initial flows were gated  at the discharge valve to achieve 100 PSI.  Proper pump pressures required increasing the RPM via the electronic governor to obtain the desired PDP.

The test nozzles had a 1 1/2" inline gauge installed at the inlet with a 0-300 PSI gauge

Nozzle readings were obtained at the inlet gauge, with the understanding that this represents a slight inaccuracy.

The line was operated from a discharge which is manifolded through a Hale foam system, with a paddlewheel flow sensor.  The flow sensor was checked and found to be fairly close to accurate by use of a pitot tube.

Test 1.
The testing began with the TFT automatic nozzle.  As I mentioned, the goal was to pump the lines at 100 PSI at the discharge gauge and see what the yield GPM was.  When evaluating the TFT, little nozzle reaction was noted, however we did not measure reaction force.  One firefighter was able to handle the hose easily.  The stream shows the focus point of the water fairly close to the baffle, which is a good visual indicator of low flow.  We "trimmed" the stream back a bit from the stop point where it would be as close to a solid column of water as possible without the water colliding and crossing over itself.  Anyone who works with automatics knows that you have to tweak the nozzle pattern adjustment as the flow increases and decreases to keep the straight stream ideal, since the movement of the baffle changes the pattern slightly.

A flow of 85 GPM was registered on the flow meter at 100 PSI PDP

The TFT automatic flow increased to 150 GPM at a PDP of 180 PSI

It is fair to say the TFT performed as expected.  The nozzle did what it is designed to do in both tests, adjust its baffle to make a usable stream with the given inlet pressure and flow.  It worked "wrong" at first because we used it "wrong" at first.  We knew that would happen, but we want you to know it, and we want you to see it.  If you run the math based on old school theoretical values, the TFT should have been pumped at around 170 PSI.  The piping loss would result in about 10 PSI extra, putting us at the 180 PDP we got.  I expected the pressure to be a bit lower with the larger ID of the hose, but the slight variables in the testing equipment, piping and flow meter cannot pinpoint the actual number, nor is it necessary to.

Test 2.  

The nest test subject was the 7/8" smooth bore at 100 PSI PDP.  The stubby Akron tip was attached to a standard Akron full ball valve shutoff.  We noted a flow of approximately 120 GPM on the flow meter, with the use of a handheld pitot tube, we got a reading of approx 32 PSI (124 GPM) which corresponds to the flow meter with only a 4 GPM difference.  The hose was expectedly soft at the nozzle inlet and prone to kinks without care being used but the stream of water delivered was still effective with a decent reach and continuity.  

The 7/8" tip yielded 120 GPM at 100 PSI PDP

The 7/8 Tip was increased to 150 GPM, and we noted a 145 PSI PDP.  We recognized the tip was 10 GPM under pumped, but we wanted to keep the flows equal from nozzle to nozzle.  The net improvement from test 1 to test 2 was a gain of 35 GPM by switching nozzles and using the same PDP.  The nozzleman had no notable issue controlling this hoseline in either test.

Test 3.

The last test subject was the Elkhart SM-30 Automatic nozzle.  We expected similar results to the TFT.  The automatic nozzle had a usable stream and was manageable for the single firefighter holding it in the first part of the test.

The Elkhart SM-30 yielded 75 GPM at 100 PSI PDP

When we performed the SM-30 test, the results ended up surprising me.  It flowed 10 GPM less than the TFT at 100 PDP.  When we boosted the pump pressure to achieve 150 GPM, it required a PDP of 160 GPM.  This was certainly more favorable than the higher 180 PSI for the TFT.  The nozzleman had more difficulty controlling this hoseline at 150 GPM

The test results are good data to review.  Please remember to do your own testing and verification.  I want to remind everyone we did not evaluate these nozzles for the sake of creating a matched hose and nozzle system, but simply to see how they would perform when improperly pumped as well as properly pumped.

When looking at all 3 nozzles, it is apparent that the smooth bore was more forgiving with low hoseline pressures and can be expected to provide the highest flow under such circumstances, regardless of the reason for the low pressure.  This is an important factor you should consider.  The 7/8" tip yielded 35 GPM more than the TFT and 45 GPM more than the Elkhart at 100 PSI PDP.  If we tested a low pressure fixed orifice combination tip, we could expect some very similar results to the smooth bore.

In summary, I urge you to carefully consider your hose and nozzle setup and consult with experts oin the field of this science.  Sales associates aren't always as educated as you trust them to be, and it is important to seek out your own information and set up testing.  It is even more critical to assure you're pumping the proper amount of water when performing structural firefighting.  The minimum goal you should aim for is 150 GPM, as it represents a flow that has been proven to have effective fire knockdown power and is manageable for a 1 or 2 person nozzle team.

I wish to extend a thank you to the firefighters I work with for their assistance gathering this great data.  Please feel free to comment on the Facebook page.

-Mike G.

CAFS Pressurized Water Extinguisher Modification

Without a doubt, one of the most common inquiries I have gotten is about how to modify a pressurized water extinguisher to create the "CAF" extinguisher featured in the video on our YouTube channel. Here is a brief article explaining it. 

With any tool modification, you need to remember that the manufacturer may not advocate or sanction the modification.  Do so at your own risk.  

The modification came to us from one of the guys I used to work with. He had worked with these extinguishers in his volunteer company and they found them to work well.  The principle of the modification is to create a class A foam extinguisher that provides a more aerated foam when discharged.  The total liquid volume of the extinguisher is only 1 3/4 gallons as opposed to the standard 2 1/2 gallons. The extra air helps to aerate the stream and expel the solution. The foam is good for increasing the effectiveness of the extinguisher as well as for laying down a barrier to help slow and stop brush fires when hose lines cannot be stretched fast enough. Every engine in our firehouse has one of these extinguishers along with standard water and other special agent extinguishers. Our brush rig has two of them. 

The modification is fairly simple. The steps are as follows.

1. Mark the extinguisher properly.  Since we do not carry AFFF foam extinguishers, we marked them red with "FOAM" on the tape stripe
2. Discharge the entire extinguisher and disassemble it
3. Remove the pickup tube and head assembly
4. Drill a single 1/16" hole at the top of the pickup tube, no more than 2" from the top where it connects to the head.
5. Measure 1 3/4 gallons of water in a pail and fill the extinguisher with it.  A large funnel helps.
6. Add 4-8 Oz Class A foam (depending on how bubbly you want it)
7. Reassemble the extinguisher
8. Shake vigorously
9. Repressurize to the recommended pressure (usually 100 PSI)
10. Deploy your CAF extinguisher!

Take note that you do not need a foam tip for this to work, although the use of an aerating foam tip that is normally supplied with pressurized AFFF extinguishers will create even better foam.

*Follow appropriate refilling precautions as recommended by the manufacturer*

Place a marking band of tape on the body of the extinguisher.  We chose red and lettered it as "Foam". 

Drill a single 1/16" Hole in the pickup tube about 1-2 inches from the top.  This hole must be above the water line.

Mark a pail or bucket at the 1 3/4 gallon mark (7 quarts or 6.62 Liters).

Mark the handles with colored take to indicate the agent.  Here blue is water, red is foam and purple is Purple-K

Thanks for stopping by and be safe out there.  -MG

Water Transfer Testing-Jet Siphon Flow Rates

Fairmount Fire Company

Water Transfer Exercise

9/24/2013

About a week and a half ago a good friend invited me along to observe a series of tests of the potential to transfer water using jet siphon devices.  The following results are our non-scientific data that were collected.  It was a great opportunity to get some baseline data on a topic that has little published information.

The Fairmount Fire Company protects a portion of Washington Township, in Morris County NJ.  Their response district includes some areas with hydrants, but is largely unhydranted.  The company operates two engines a tender and a support rig.  You can learn more about them at www.34fire.org

The goals of this drill were to;

1. Test the potential flow rate of jet siphon devices using one and two devices
2. Test the potential to transfer water up a grade through a jet siphon device

The setup for the first part of the test included;

• (1) 3500 Gallon folding tank (Tank #1)
• (1) 2000 Gallon folding tank (Tank #2)
• (1) Kochek “JS60” power jet siphon device connected to (2) 15’ x 6” suction hose
• (1) Kochek “JS60 power jet siphon device connected to (2) 10’ x 6” suction hose
• Clamp-on hose bracket with (2) 2 ½” hose connection elbows on the 3500G tank

Preparation for tests #1-4

• Two tanks were set up approx 3-4 feet apart, on flat asphalt, with a slight incline
• The 3500 gallon tank sat on the “downhill” side
• The 2000 gallon tank sat slightly “uphill” from the larger tank
• E34-62 pumped its 1000 gallons of booster tank water into the 3500 gallon tank through the clamp on hose bracket.
• Once the booster tank had been emptied, a mark was made on the sidewall of the tank indicating the 1000 gallon water level
• Using a tape measure, corresponding marks were added for 500, 1500 and 2000 gallons along the tank sidewall.  It should be noted that the 3500 Gallon tank was only able to hold about 2000 gallons due to the pitch of the parking lot
• (2) 15’ sections of hard sleeve were connected together and the Kochek jet siphon was attached.  The intake for the siphon was placed at the lowest “downhill” point in the 3500 gallon tank
• 50’ of double jacket-rubber lined hose was connected from the pump panel discharge of Tender 34 to the jet siphon
• A stopwatch was set to 00:00
• After each test, water was pumped back into tank #1 by E34-62, utilizing the clamp-on 2 ½” hose connection bracket.
• Time was recorded at each 500 gallon interval 

Preparation for test #5

• 3500 Gallon tank on the "downhill side"
• 2000 Gallon tank on the "uphill side"
• 50' of 6" hard sleeve with an approximate 7' elevation

Test #1

Objective: Determine flow rate of water from nozzle of jet siphon at different pump pressures through 50’ of 1 ½” hose.

The “JS60” Siphon used

The jet siphon was evaluated and noted to have a single ¾” nozzle orifice with a 1 ½” NH hose connection.  It has 6” male NH thread to connect to the hard sleeve hose.  A check of a smooth bore discharge chart shows the ¾” nozzle listed and therefore we can deduct the measurements taken with the handheld pitot gauge are generally accurate.

Water transfer back to original tank

The jet siphon was held by a firefighter and aimed into the portable tank.  The handheld pitot gauge was used to measure the pressure of the stream exiting the nozzle.

Results of Test #1

The flow test resulted in the following performances. 

• PDP - 75 PSI = 50 PSI nozzle pressure or approximately 120 GPM
• PDP - 100 PSI = 70 PSI nozzle pressure or approximately 140 GPM
• PDP of 125 PSI =  80 PSI nozzle pressure or approximately 150 GPM
• PDP of 150 PSI = unknown nozzle pressure – not tested

It should be noted that the sharp 90 degree bend of the nozzle pipe in the device results in a very broken stream, with fluctuations on the pitot gauge.  The values measures represent a good “average assessment” while holding the pitot gauge in the stream for approx 10-15 seconds.

The following table lists the flow data collected

PDP                 Flow                 Friction Loss (Hose) Approx.     Tip PSI             Device Loss (estimated)

75 PSI              120 GPM          34.6 PSI/100’ or 17.3 PSI/50’      50 PSI Tip         7.7 PSI

100 PSI             140 GPM          47 PSI/100’ or 23.5 PSI/50’         70 PSI Tip         6.5 PSI

125 PSI             150 GPM          54 PSI/100’ or 27 PSI/50’           80 PSI Tip         18 PSI

150 PSI             160 GPM          61.4 PSI/100’ or 30.7 PSI/50’      100 (estimate)   19.3 (estimate)

Test #2

Objective: Determine flow rate of single jet siphon to transfer 1000 gallons of water from one folding tank to another at 100 PSI pump discharge pressure.

The 3500 Gallon tank was marked at 500 gallon intervals with the top mark being 2000 gallons. 

The stopwatch was started when the discharge valve was opened.  The water level started at the 2000 gallon mark.  When the water level reached the 1500 gallon mark the time was recorded.  It was recoded again at the 1000 gallon mark.

The jet siphon was attached to (2) 15’ sections of 6” lightweight suction hose

 Tank Markings made using a tape measure and a measured quantity of water (1000 Gallons)

Results of Test #2

With a pump discharge pressure of 100 PSI the following results were achieved.

Water level at the 1500 Gallon mark (500 gallons transferred):      1:27

Water level at the 1000 Gallon mark (1000 gallons transferred):    3:22

Average flow rate for 1000 Gallons         4.95 Gallons/second or 297 GPM

Average flow rate for first 500 Gallons    5.74 Gallons/second or 344 GPM

Average flow rate for last 500 Gallons    4.34 Gallons/second or  260 GPM

The discharge gauge readings between the main pump and the line gauge were virtually identical at the 100 PSI test

Summary of Test #2

It appeared that the first 500 gallons of water transferred at a higher flow rate, while the last 500 gallons of the test transferred at a lower rate.  The difference in flow between the first and last 500 gallons was an 84 GPM decrease.  We felt that because the siphon action does not use the advantage of positive pressure that as the water level in the tank lowers that it requires more energy to raise the water up the suction hose, thus showing the decline in flow. 

The average flow of 297 GPM also did not account for “prime time” of the siphon, so the actual true flow rate might be slightly higher

Because the known flow of the jet siphon nozzle at the 100 PSI pump pressure is approximately 140 GPM, the average net flow rate of the transfer device is actually 157 GPM.  This could be considered the flow rate of a single 1 ¾” handline

Test #3

Objective: Determine the flow rate of two jet siphons to transfer 1000 gallons of water from one folding tank to another at 100 PSI Pump discharge pressure

The 3500 Gallon tank was marked at 500 gallon intervals with the top mark being 2000 gallons. 

The stopwatch was started when the discharge valve was opened.  The water level started at the 2000 gallon mark.  When the water level reached the 1500 gallon mark the time was recorded.  It was recoded again at the 1000 gallon mark.

The first jet siphon (#1) was attached to (2) 15’ sections of 6” lightweight suction hose.  The 50’ section of 1 ½” hose was connected to the pump panel discharge of Tender 34, shown below.

The second jet siphon (#2) was attached to (2) 10’ sections of 6” lightweight suction hose.  The 50’ section of 1 ½” hose was connected to the rear discharge of Tender 34.  The discharge is located to the lower right of the dump chute.

       

The photos show the piping and location (lower right) of the rear discharge on T34

Results of Test #3

With a pump discharge pressure of 100 PSI the following results were achieved.

Water level at the 1500 Gallon mark (500 gallons transferred):                  1:02 (62s)

Water level at the 1000 Gallon mark (1000 gallons transferred):                2:12 (132s)

Average flow rate for 1000 Gallons         7.57 Gallons/second or             454 GPM

Average flow rate for first 500 Gallons    8.06 Gallons/second or             483 GPM

Average flow rate for last 500 Gallons    7.14 Gallons/second or              428 GPM

Summary of Test #3

It appeared that the first 500 gallons of water transferred at a higher flow rate, while the last 500 gallons of the test transferred at a lower rate, as in test #2.  The difference in flow between the first and last 500 gallons was a 55 GPM decrease.  We felt that because the siphon action does not use the advantage of positive pressure that as the water level in the tank lowers that it requires more energy to raise the water up the suction hose, thus showing the decline in flow. 

The average flow of 454 GPM also did not account for “prime time” of the siphon, so the actual true flow rate might be slightly higher

Because the known flow of the jet siphon nozzle at the 150 PSI pump pressure is approximately was not tested, the average net flow rate of the transfer devices is estimated at 174 GPM.  This could be considered the flow rate of a single 1 ¾” handline.

After reviewing the piping on Tender 34, we noted that the rear discharge contains several sharp bends, and that the pressure gauge line is affixed close to the pump.  It can be deducted that because of this, that jet siphon #2 was somewhat underpowered due to pressure loss in piping.  In addition, due to the difference in length of the two hard suction lines it can be deducted that there may have been a slightly lower level of efficiency in the longer of the two lines.  There were (4) 90 degree elbows and (2) 45 degree elbows identified within the pump house.  It is assumed once the piping reaches the last visible bend that it runs straight to the rear along the frame, but this was not certain.

The flow rate of approximately 280 GPM (140 GPM ea.) is required to support the two jet siphon devices, and thus makes this water unavailable for the fire site.  This must be considered in the pumps total capacity, especially since operating at draft as well as the required pump pressure (100 PSI) to achieve the flow.

Test #4

Objective: Determine the flow rate of one jet siphons to transfer 1000 gallons of water from one folding tank to another at 150 PSI pump discharge pressure

The 3500 Gallon tank was marked at 500 gallon intervals with the top mark being 2000 gallons. 

The stopwatch was started when the discharge valve was opened.  The water level started at the 2000 gallon mark.  When the water level reached the 1500 gallon mark the time was recorded.  It was recoded again at the 1000 gallon mark.

The jet siphon (#1) was attached to (2) 15’ sections of 6” lightweight suction hose.  The 50’ section of 1 ½” hose was connected to the pump panel discharge of Tender 34

Results of Test #4

With a pump discharge pressure of 150 PSI the following results were achieved.

Water level at the 1500 Gallon mark (500 gallons transferred):                  1:11 (71s)

Water level at the 1000 Gallon mark (1000 gallons transferred):                2:18 (138s)

Average flow rate for 1000 Gallons         7.24 Gallons/second or             434 GPM

Average flow rate for first 500 Gallons    7.04 Gallons/second or             422 GPM

Average flow rate for last 500 Gallons    7.46 Gallons/second or              447 GPM

Summary of Test #4

It appeared that the first 500 gallons of water transferred at a lower flow rate, while the last 500 gallons of the test transferred at a higher rate, as compared to the other tests.  This represents an inverse result to the previous pattern. The difference in flow between the first and last 500 gallons was a 25 GPM increase.  As stated, this is the opposite result of previous tests.  We can theorize that the higher velocity of water from the jet may have impacted this result, but have no other data to explain this difference.

The average flow of 434 GPM also did not account for “prime time” of the siphon, so the actual true flow rate might be slightly higher

The estimated flow of the jet siphon nozzle at the 150 PSI pump pressure is approximately 167 GPM, the average net flow rate of the transfer devices is actually 267 GPM.  This could be considered the flow rate of a single 2 1/2” handline or two 1 ¾” handlines.

Test #5

Objective: Determine the flow rate of one jet siphon to transfer 1000 gallons of water from one folding tank to another at 150 PSI Pump discharge pressure up an approximate 7’ elevation.

The 3500 Gallon tank was marked at 500 gallon intervals with the top mark being 2000 gallons. 

The two tanks were 3500 gallons each.  The lower tank was filled to capacity; the upper tank retained its water level markings.

50 total feet of hard sleeve were connected together (2) 10’ and (2) 15’ sections

E34-62 was connected to a 6’ low level strainer in tank #2 (uphill tank) and had approx 500 gallons of on board tank water.  The level of water in tank #2 was at the top of the opening to the strainer, and unsuitable to draft at the start of the test.

The stopwatch was started when the discharge valve on E34-62 was opened.

Test #5

Results of Test #5

Water was discharged from the 6” hard sleeve into tank #2 (uphill), but it was noted to have a low volume, and did not fill the entire hose coupling opening.

After exhausting approximately 500 gallons of remaining tank water, E34-62 was unable to establish an effective transfer and the operation stopped.

Summary of Test #5

The test failed.

While attempting to prime the siphon, E34-62 operator increased pump pressure to near 200 PSI, with no appreciable results.  It was also noted that tank #1 (downhill) began to overflow, leading us to believe that the tank water from E34-62 was simply being exhausted into this tank and backflowing out of the siphon. A small stream of water exited the uphill end of the suction hose, but never gained enough water to establish a draft with the low level strainer.

We believe that the action of the jet siphon is limited to very slight elevation differences.  It would seem logical that because the action of the siphon it requires more energy to “prime” itself and flow than if the water were being pumped through the hard sleeve.  With that conclusion, we felt that dump site setup is critical when elevation is a factor and that the following options exist in such a situation;

• Portable pumps
• Drafting out of tanks directly and pumping back into other tanks

Overall Conclusions

After running the previous tests, we came to a few conclusions, which are listed below.  Understanding that without additional test gauges and more precise testing parameters, that the results have a known “approximation” built in, however, we can still consider the data is fairly consistent to use for “real world” purposes.

• Regarding the pressure to pump the jet siphons at, we felt that the best results were at the 150 PSI PDP and that a flow of 125-150 PSI PDP will yield best results in most cases
• Regarding how many jet siphons to use for water transfer, we felt that no less than two should be used as a standard practice between each tank
• Regarding the hose supplying the jet siphons, we used 1 ½” hose, 1 ¾” hose may yield better performance due to lower friction loss
• The use of the primary fireground supply pumper for water transfer beyond 2-3 jet siphons will impact its ability to deliver higher volumes to the fire scene.  With a flow of 160+/- GPM per siphon, this can add up quickly.  The operator should consider the flow of a jet siphon as equivalent to a typical 1 ¾” handline when factoring in total water supply.  Also, this water being used in each siphon is “recirculated” and never delivered to the fire, hence why we mentioned the “net” flow of each siphon.
• Using a separate pumper for water transfer may be a preferable option at large scale fire events, to allow the primary supply pumper to flow its best possible capacity to the fire site.
• When elevation is an issue, water can be transferred downhill, but not uphill beyond slight elevations when using jet siphons.  Dump site setup should consider this factor
• The discharge end of the hard sleeve must remain above the static water line in the folding tank, failure to maintain this position will result in high likelihood of back flow, as when the flow stops from the jet, the transfer will tend to reverse itself and return the water back to the original tank.
• Portable tanks on uneven ground will not hold their capacity, and additional tanks may need to be deployed on inclines to compensate for the lowered overall capacity
• You can mark the liquid level of folding tanks, but doing so must be done on level ground and there must be an understanding that if the tank is uneven that the level will be inaccurate.  One way to make this issue more apparent is to mark opposite sides and compare the levels.  If nothing else, it serves to indicate an approximate liquid level, as most fires don’t happen on flat, level ground.
• Water supply officers have a dity to collect additional suction hose, strainers and jet siphon devices from tanker and engine companies assigned to the operation, in order to be able to build an effective dump site.  Be familiar with thread size of hose and appliances used by mutual aid companies.

At the time we ran this rtest, we had no good information reporting the potential performance of jet siphons.  We were made aware that www.gotbigwater.com did some comprehensive tests in 2012, which you can find on their site.  http://www.gotbigwater.com/content/data/file/Jet%20Siphon%20Flowtests.pdf

Fairmount Fire Co. should be commended for quickly unloading and setting up all the required equipment and taking the time out of their evening to run these tests.  -Mike G.