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29 December 2011

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.

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