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.