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#60 - Double Jacket Fire Hose Comparison: 2 inch Fire Hose vs. 1¾ inch vs. 1½ inch:

Posted by Jason Hugo and Courtney Montanye on 12/16/2016 to Fire Hose
If you currently use a specific size of double jacket fire hose and are considering a switch to a different size, you’ve come to the right place. In this article, we're going to compare from a form and function perspective three different sizes of double jacket fire hose: 1½”, 1¾”, and 2”. This kind of hose is commonly used as attack line hose in fire fighting and in a variety of commercial applications such as pumping, wash downs, and more. Each size comes with benefits and drawbacks outlined for below. 

If your mind is already made up and you are looking for a great selection of 1½”, 1¾”, and 2” double jacket fire hose, browse QRFS' selection here

Fire Hose Background

A little background before we begin. The size measurement we are referencing - 1½”, 1¾”, and 2” -  is the diameter of the inside rubber hose liner. The double jacket attack line fire hose we're comparing is made of a flexible EPDM rubber line covered in woven fabric. It's purpose is to bring water from a water pump to the nozzle. Available sizes for double jacket attack line hose ranges from 1” to 3”, but for this article we are focusing on the three most common diameters: 1”, 1¾”, and 2”. Each size is manufactured and tested to operate at up to 400 Pounds per Square Inch (PSI - if you’re not sure what that means, we’ll explain in a moment). Sometimes, a large diameter attack line hose is used as supply line hose, carrying water from a hydrant to a truck or from one truck to another, however for the purpose of this blog we’re focused on attack line only. 

Per the National Fire Protection Agency, an attack line hose is designed to be used by trained firefighters and fire brigade members to combat fire beyond the fire’s incipient, or initial, stage. This type of hose gets its name when used to ‘attack’ an outside fire or during initial structure breach. 

Detroit Firefighter Using 1.5 Inch Attack Line
A Detroit Firefighter using a 1½" attack line (Image Source)
 
The 1½”, 1¾”, and 2” fire hose we’re comparing have uses outside of fighting fires. Rock quarries use them to pump excess water from the quarry bottom. Because they carry more water than a pressure washer, they’re great for cleaning large surfaces. For instance, Denver Pressure Washing Services uses fire hose when they must clean parking garages in a short amount of time or when there is heavy build-up. Often, ocean piers use them for the very same reason.

GPM, PSI, and Friction Loss

If you’re going to compare the benefits of different hose, there are some terms you will need to be familiar with. Three of the most common measurements associated with fire hose are Gallons Per Minute (GPM), Pound per Square Inch (PSI) and friction loss

GPM is equal to the flow rate of one gallon in one minute that a fire hose can put out. The GPMs that are mentioned in this blog are not uniform to each hose of the same size. The GPMs that you experience might be greater or lesser than what is mentioned because of numerous factors, such as the nozzle or the pressure from the water pump. 

PSI is the pressure that a liquid (or gas) exerts on the walls of its container. For our purposes, this means the pressure which the water presses against the inside liner of the hose. It’s extremely important to know that not only are GPM and PSI NOT interchangeable, but they cannot be converted from one to the other. The NFPA does not have a set GPM a hose must meet to be considered an attack line, but it must operate with a test pressure of at least 300 PSI. 

What about friction loss? Firehouse.com calls it the loss of pressure within a hose due to the internal resistance of the water against the hose lining. It’s affected by three factors: flow, hose length, and size of hose. For each of the three hose sizes compared in this article, there is a friction loss of of approximately 30 PSI per hundred feet.

Attack line fire hose are reinforced with a woven fabric layer called a “jacket.” These can come with either single or, as we're focused on, double jackets. For obvious reasons, single jacket fire hose is lighter and more flexible, but they are also less durable. These are better suited for less frequent use. 

Double jacket fire hose is inherently more durable because of the two protective outer layers; however, this also makes it heavier and less flexible. A double jacket fire hose is better suited for firefighters because of the frequency of use. The double jacket fire hose is what we will be focusing on throughout the remainder of this blog. 

Double Jacket Fire Hose
You can see why it's called a double jacket fire hose (Image Source)
 
QRFS distributes, and we're comparing, fire hose from Superior Fire Hose. QRFS.com offers Superior Hose for contractors and industrial uses in addition to more traditional firefighting. Each hose is offered in 50, 75, or 100 feet lengths. By following proper procedure for cleaning, use, storage, testing, and inspection, Superior’s Made in the USA Fire Hose can last 10 years or longer. For this comparison, we’re using 1½”, 1¾”, and 2” Superior Fire Hose Double Jacket 400 PSI in 100-foot lengths. Double Jacket Fire Hose is available in 200 PSI for contractor applications and 300 and 400 PSI for municipal purposes. 

The Comparison: 1½ inch vs 1¾ inch vs 2 inch Double Jacket Fire Hose

A lot of people have a personal preference when it comes to which size fire hose to use. If your mind is made up, then please do not let us stand in your way. However, when we compared them we found that each size offers a trade-off between weight and water output. 

A staple across all three we compared was the 1½” coupling. While 2” does offer a 2” coupling, for our purposes we looked at models featuring reducing couplings from either 1¾ “ or 2” down to 1½”. 

Finally, let’s bring back the topic of GPM. To better understand the effect that a hose diameter has on GPM, let’s use a simplistic example: we're filling a 13,000-gallon above-ground swimming pool with our comparison hoses. 

1½" Double Jacket Fire hose

1½” is the reigning champion of the double jacket attack line fire hoses. It’s no secret that the smaller the diameter, the easier it is to maneuver and the fewer men it takes to use it, making it the leader in those areas.  Available in a range of PSI, the 1½” fire hose can flow about 150 GPM and up. A 100-foot length of 400 PSI 1.5" Superior Double Jacket Fire Hose weighs 29.6 lbs dry. Using our 13,000-gallon swimming pool, it would take you 87 minutes to fill it. 1½” was the lightest hose we compared, but also flowed the least amount of water, resulting in the trade-off between usability and function. 

If we use simple math we can compare our hose side by side. The 1½" double jacket fire hose provides 5.06 gallons per minute per dry pound of hose (150 GPM / 29.6 lbs dry = 5.06 GPM/pound). Wonder if that's the best we can get? 

Detroit Firefighter's Using 1.5 inch Attack Line
Two Detroit Firefighters were able to put out this fire with just two 1½" hose lines (Image Source)

1¾" Double Jacket Fire Hose

1¾” is slowly taking away the championship title from 1½”. It has even been called the “all-purpose” hose because of its balance between flow capabilities and flexibility.With the increase in diameter, a 100-foot length of 400 PSI 1.75" Superior Double Jacket Fire Hose jumps in weight up to 34 pounds dry, almost 5 lbs heavier than the 1½”. However, the output of water also increases - now up to 180 GPM -  due to the drop in friction loss.  So how about that swimming pool? Well, you need 73 minutes fill it with this 1¾” fire hose. Putting that into another perspective, if it took 13,000 gallons of water to put out a fire or clean a pier, you could do your job 14 minutes faster with the 1¾” fire hose compared to 1½". 

So how many GPM per pound is the 1¾"? 5.29 GPM/pound. Better, but only about .23 GPM/pound better. 

2" Double Jacket Fire Hose

If you’re looking to get the most bang for your buck, then consider the 2” double jacket attack line fire hose. The 2" Double Jacket Fire Hose 400 PSI weighs in at a whopping 40 lbs dry. However, it can flow up to 250 GPM. The 2” is a great alternative to a wider hose, such as a 2½”, for high-rise buildings because it’s lighter and more maneuverable while still flowing a considerable amount of water. But what about that swimming pool? With this size, you’ll only need to wait 52 minutes before the pool is full, cutting a full half hour. 

How about in GPM per pound? Well the 2" hose comes in at 6.25 GPM/pound. So if that was the only metric we were considering, you definitely get considerably more water per pound lifted. But of course, that was dry weight and sometimes it takes a long time to put out a fire or clean that pier ...

So is 2" too large for just one person? Per Fire Rescue Magazine, a single firefighter can handle flows up to 350 GPM on a 2” fire hose without issue, by simply sitting on the hose. : ) 

2 inch fire vs. 1.75 inch fire hose
The left is a 2" and the right is a 1¾". Notice the small difference. (Image Source)
 
So which is best? That's obviously a personal preference. Depending on the user's needs - and, let's face it, strength - any double jacket fire hose you select should be viewed as a measurable trade-off between weight and water availability. Ultimately, the final decision is up to you. 

Now that you have an accurate weight verse GPM comparison of double jacket attack line fire hose, come browse QRFS’ enormous selection of 1½”, 1¾”, 2”, and more fire hose sizes to suit any need. 


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