SPRAY NOZZLE RELATED CALCULATORS

Spray Nozzle Flow Rate Calculator

This calculator is meant to assist you with estimating the flow rate of a spray nozzle at pressures that aren’t listed in a catalog or if you do not have a catalog readily available. Many nozzle companies use a part number that describes the spray angle and flow rate at 40 PSI. For instance, a “6520” is usually a 65° angle flat fan nozzle flowing ~2 GPM at 40 PSI. In the example below, the flow rate at 150 PSI is calculated to be ~3.87 GPM. Ultimately this calculator can be used to determine the required flow rate for a spray header.

This equation is based upon the formula to the right. Q1 and P1 are the known flow rate and pressure. Q2 is the resulting flow rate for the pressure in question P2.

Flow rate at a new pressure

Known flow Q₁ (GPM) Known pressure P₁ (PSI) Desired pressure P₂ (PSI) Resulting flow Q₂ (GPM)

Example: a “6520” flat fan (~2 GPM at 40 PSI) gives about 3.87 GPM at 150 PSI. Flat fan, hollow cone, and solid stream use this square-root relationship.

Spray Nozzle Coverage Calculator

Our spray coverage calculator assists with estimating the number of spray nozzles required for a given spray angle, spray height based upon the coverage you require. This will enable you to minimize the number of spray nozzles required by choosing a wider spray angle or adjusting your spray height – or some combination thereof. Ultimately you may require a different percentage of overlap or there might be some other coverage related aspects to consider, however this calculator will provide a relatively accurate estimate and help you to design your own spray header. Although this calculator was created with Flat Fan nozzles in mind, it also works well for Full Cone nozzles as long as you are trying to estimate the coverage across a target.

Spray coverage / nozzles required

Spray height Spray angle (°) Total coverage required

Results

Number of nozzles required Spray coverage per nozzle Effective coverage (25% overlap)

Squared layout (single header)

Actual overlap between nozzles Distance between nozzle centers 1st nozzle center from edge

Offset layout (every other header)

Actual overlap between headers Distance between header centers 1st nozzle center from edge

Uses the same layout math as the original coverage spreadsheet. Keep height units consistent with coverage (e.g. feet with feet). Theoretical coverage is most reliable up to about 6 ft spray height.

The Actual Overlap differs from 25% to evenly space the nozzles across the header, as the number of nozzles required is a whole number.
Complex spray coverage patterns such as large circular/rectangular areas, specialized nozzle patterns such as even spray pattern nozzles and prediction of coverage for spray injected into a gas stream or pressurized vessel are all examples where this calculator is not useful.
This calculator does not take into account such variables as Surface Tension, Specific Gravity or fluid temperatures ≠ 70°F.
Spray Coverage is based upon Theoretical Coverage and doesn’t take into account the collapsing effect that gravity exerts on a pattern for very high spray heights. Theoretical Coverage is considered to be accurate for spray heights up to ~6 feet. At these heights and higher it is suggested that you contact a spray nozzle specialist and review your requirements with them.
The Effective Coverage Overlap is a suggested minimum and based upon using Flat Fan Nozzles or Full Cone Nozzles having a parabolic (tapered) spray distribution.