The short answer
50 to 75 psi: Low pressure
Pros
- Lower nozzle reaction
- More pump-pressure margin for friction loss and elevation
Tradeoffs
- Conventional attack hose may be more prone to kinking at lower operating pressures.
- Less reach at equal flows
- Purpose-built low-pressure hose can cost more.
100 psi: High pressure
Pros
- A familiar standard for many departments.
- Conventional attack hose tends to stay firmer and resist kinking.
- More reach when comparing nozzles at equal flows
Tradeoffs
- Higher nozzle reaction.
- Not the operating range typically used for solid bores.
Standardize the complete hose-and-nozzle package. Do not mix low- and high-pressure systems in the same operating setup. Different assumptions can produce the wrong pump pressure, hose selection, or nozzle setting.
1. Choose the pressure
Where lower nozzle pressure earns its keep
Every psi the nozzle does not require leaves more discharge pressure available elsewhere in the line. That matters most when elevation, distance, or limited supply consumes pressure before water reaches the tip.
High-rises
Elevation adds about 0.434 psi for every vertical foot before water reaches the nozzle.
Long lays beyond the pump
Friction loss compounds with distance, although larger supply hose should be the first consideration.
Uphill pumping
Larger hose reduces friction loss, but it cannot eliminate the pressure required to overcome gravity.
Smaller crews
Lower nozzle pressure reduces reaction at the same flow and can make the line easier to handle.
2. Choose the stream
Solid bore or fog?
Nozzle pressure and stream choice are related, but they are not the same decision. The right question is which stream characteristics your tactics and training require.
Solid bore: Simple, predictable, and efficient
Some departments prefer solid bores for their simple, repeatable stream. The open waterway has few moving parts, passes debris readily, and has no adjustable fog pattern. Actual stream performance still depends on the tip, nozzle pressure, and water supply.
- High flow at low nozzle pressure.
- Large droplets with strong effective reach and penetration.
- Less affected by wind, with water landing in a concentrated area.
- No accidental change to a wide fog pattern indoors.
Example: A 7/8-inch tip flows approximately 161 GPM at 50 psi.
Fog nozzle: More pattern choices
A combination nozzle can produce a straight stream, narrow fog, or wide fog. That flexibility gives crews capabilities a fixed solid bore does not provide, provided the crew is trained to use the pattern deliberately.
- Narrow fog supports hydraulic ventilation through an opening.
- A wide pattern can protect against radiant heat during emergency withdrawal.
- Available in fixed, selectable, and automatic designs.
Tradeoff: More components and settings require more maintenance, training, and communication with the pump operator.
3. Match the hose
The hose and nozzle are one system.
The nozzle sets the pressure requirement. The hose must remain firm enough to resist kinking at that pressure.
Conventional attack hose is designed to run firm near 100 psi. At lower operating pressures, some lightweight hose can bend and kink more easily.
- Check stability: Test kink resistance at the pressure and flow your department intends to use.
- Compare construction: More structural support or a thicker liner may help hose remain firm at reduced pressure.
- Consider handling: Low-pressure hose may be heavier and less flexible when it is dry, which can make it harder to stack neatly in preconnect hose beds.
4. Train the system
Train for different nozzle pressures. Work smarter, not harder.
Lower nozzle reaction helps, but good technique determines how effectively a crew can control and advance the line. Body position, pinning the hose with a knee, and using a coil for larger lines allow crews to work with nozzle reaction instead of fighting it.
Need help comparing systems?
Give us your requirements, and we will help you work through your ideal setup.
