Fire Hose Volume Calculator
Estimate charged hose capacity, water weight, fill time, and recoverable drain volume from hose diameter, section length, number of lengths, and flow rate.
| Nominal inside diameter | Approx gallons per 50 ft | Approx liters per 15 m | Typical use |
|---|---|---|---|
| 3/4 in booster | 1.15 gal | 13.0 L per 30 m | Booster reels and light mop-up lines |
| 1 in forestry | 2.04 gal | 30.4 L per 30 m | Wildland hose packs and long hand carries |
| 1-1/2 in attack | 4.59 gal | 34.1 L per 15 m | Small attack lines and standpipe packs |
| 1-3/4 in attack | 6.25 gal | 46.4 L per 15 m | Common structure fire attack line |
| 2-1/2 in handline | 12.75 gal | 94.8 L per 15 m | Large handlines and exposure streams |
| 3 in supply | 18.37 gal | 136.5 L per 15 m | Feeder, relay, and supply hose |
| 4 in LDH | 32.65 gal | 242.7 L per 15 m | Large-diameter hydrant supply |
| 5 in LDH | 51.02 gal | 379.2 L per 15 m | High-volume supply and relay pumping |
| Planning item | Calculator input | What it changes | Field note |
|---|---|---|---|
| Inside diameter | Hose diameter | Volume by diameter squared | Small ID changes have a large effect on volume. |
| Section count | Number of lengths | Total charged volume | Include every section between pump, appliance, and nozzle. |
| Fill rate | GPM or L/min | Fill time only | Actual filling may be slower due to air, kinks, elevation, and valve control. |
| Drain recovery | Drain percent | Recoverable water | Use lower percentages for uneven ground or hose left partially charged. |
| Allowance | Coupling and sag percent | Planning margin | Useful when hose snakes through corners, stairs, or uneven terrain. |
| Water volume | Fresh water weight | Metric equivalent | Planning context |
|---|---|---|---|
| 5 gal | 42 lb | 19 L / 19 kg | Short attack section or small booster amount |
| 25 gal | 209 lb | 95 L / 95 kg | Several charged attack lengths |
| 50 gal | 417 lb | 189 L / 189 kg | Large handline or partial supply lay |
| 100 gal | 834 lb | 379 L / 378 kg | Long supply lay drainback planning |
| 250 gal | 2,085 lb | 946 L / 944 kg | Multiple LDH sections or relay hose volume |
| Field condition | Suggested allowance | Why it matters | Calculator setting |
|---|---|---|---|
| Straight measured hose bed | 0% to 2% | Little extra hose curvature or trapped water | Use 0% or 2% |
| Normal attack stretch | 5% | Allows for couplings, slight bends, and working slack | Default 5% |
| Stairwell or standpipe pack | 5% to 10% | Hose bends and vertical routing can retain more water | Use 5% or 10% |
| Long LDH supply lay | 10% | Snaking, appliance spacing, and terrain increase practical volume | Use 10% |
| Uneven terrain or relay | 10% to 15% | Low spots can hold water after initial drain | Use 10% or 15% |
When a fire hose is charge with water, the water that is inside of a fire hose have weight. The weight of the water inside of an fire hose can impact a crew’s ability to move the fire hose, as well as the strain that a standpipe connection will have to endure due to the weight of the water. Furthermore, the weight of the water will also impact whether the ground will be able to accept the water when the firefighters drain the fire hose.
Many people pay significant consideration to the nozzle pressure and flow that is projected from a fire hose. However, the amount of water that is contained within the fire hose is also a critical factor that should be considered in planning for a fire hose deployment. If the fire department does not correctly estimate the amount of water that is to be contained within the fire hose, the fire hose may end up being too heavy for the firefighters that are to handle it, or the recovery tank may end up being too short for the water that is to be discharge from the fire hose.
How Much Water Is in a Fire Hose and How Heavy It Is
The most important factor to consider regarding the volume of water that may be contained within a fire hose is the inside diameter of the fire hose. The volume of water that is contained within a fire hose increase in relation to the square of the radius of the fire hose, meaning that a relatively small change to the inside diameter of a fire hose can have a significant effect upon the total volume of water that is to be carried by that fire hose. For instance, a 1-3/4 inch attack line and 2-1/2 inch handline may be similar in size, but the 2-1/2 inch handline will carry roughly twice the amount of water that the attack line can move.
This is why it is important that the diameter of the fire hose is measured to ensure accurate calculations; the calculator allow for the inside diameter of the hose to be entered directly into the calculation to avoid the use of conversion charts. The length of the fire hose, in combination with the quantity of fire hose sections that are to be utilize, will impact the total volume of water that is to be moved by those fire hoses. It is possible for only one 50-foot section of fire hose to be relatively lightweight when empty, but using numerous 50-foot sections will eventually add to the weight of the fire hose.
The calculator allows for the length of the fire hose to be entered, as well as the quantity of fire hose sections that are to be deploy. Furthermore, the calculator also incorporates an allowance for the weight of the couplings, the bends in the fire hose, and for the fire hose to sag between fire hose sections. A five percent allowance is used for normal attack fire hose stretches, but a greater percentage may be required for supply lays or stairwell packs.
This percentage can be entered into the calculator to ensure accuracy. The percentage of how the fire hose is to be filled with water, as well as the percentage of how much water will be recovered when the fire hose is drained, are two parameters that will help to transform the volume calculation into a planning tool. The amount of water that is discharge from the fire hose may differ based off the terrain upon which the fire is fought.
By entering the percentage of how much water the firefighters are to recover, that percentage can help to make decision regarding the number of firefighters that will be assigned to the fire, the size of the basin in which the water will be collected, and how long it may take to perform the required fire hose cleanup. The flow rate of the fire hose is used only in calculating the time that it may take to fill the fire hose with the required volume of water. It does not impact the volume calculations of the fire hose.
However, it can provide an estimate of the time that it will take to fill the fire hose to the desired level. However, the actual time that it may take to fill the fire hose with water will likely be longer than estimated due to air that must exit the fire hose, as well as the slow opening of the fire hose valves. An estimate can be provided by the fire department using the fire hose volume calculator, but adjustments can be made to that estimate based upon the knowledge that each firefighter has of their fire hose equipment.
Beyond diameter and length, there are other factors that impact the decision of whether fire hoses will be used as attack lines or supply lines. Attack lines are move while they are being charged with water, so the weight of the attack lines will have an impact upon the fatigue of the firefighters that are using those fire hoses. Additionally, supply lines are typically in place for longer periods, and they are required to move greater amounts of water than attack lines.
Thus, fire department manager must consider the drain volume of supply lines. Additionally, supply lines may contain different types of fire hose than attack lines; rubber covered booster fire hose is used in one way, while double-jacket attack fire hoses may be used in another way. On training days, fire departments use fire hose volume calculators.
Each fire department makes the assumption that each fire hose has the same capacity. However, if the department introduce a new supply line but fails to increase the size of the recovery basin, the fire hose will overflow. The fire hose volume calculator can make these types of comparison quickly and accurately, but only if they are used prior to teh fire hose is charged with water.
The density of the water that is contained within the fire hose can have an impact upon the overall weight of that water. The default water density in the fire hose calculator is set to the weight of fresh water at room temperature. However, the weight of the water change if the water is colder or if the water contains minerals.
While the difference in weight is insignificant for one attack line fire hose, the difference in weight has the potential to become significant for fire departments moving large amounts of water over long distances or elevations. The density of the water can be adjusted within the fire hose calculator. The most common mistake when using this type of fire hose calculator is to treat the volume number as a final number.
However, that number is the result of the diameter, length, quantity, fill percentage, and the allowance for fire hose sagging. Any change to any of these factor will change the volume number. Once the factors that impact the fire hoses volume are understood, the fire hose calculator can be used to test various factor to determine the best choice.
For fire departments, the most important benefit of using this type of fire hose volume calculator is that the crew can know the actual weight of the water that will be inside of the fire hose prior to extending it. If the weight of the water is known, the department will know how many firefighter are required to assist in moving the fire hose, how the recovery basin should be set up, and how long it will take to complete that fire departments fire fighting efforts. Although the calculation of the weight of the water is simple, using that calculation prior to extending the fire hose will save the department time when performing the calculations after the fire hose has been stretched.
