Spray Nozzle Selection Guide

This page describes some of the questions to be considered when selecting spray nozzles. In addition, answers for uncomplicated situations are provided where possible. In some applications, because of the large number of variables involved, accurate answers are not always possible except through actual testing or simulation. Our technical staff, however, may be able to give assistance in their areas of expertise. Please feel free to give us a call.

What Spray Nozzle Construction Do I Require?

The basic elements of spray nozzle construction are pipe connection, physical dimensions, and material of construction.

Pipe connection

connection is described by type, size, male, female, or flange. Nozzles described in this catalog have BSPT threaded pipe connections (NPT are also available for most models).

Size

Standard sizes from 1/8 BSPT to 4" BSPT, or as indicated.

Male and Female

connections are available where indicated

Physical Dimensions

are listed throughout this catalog. They are set at our factory and we recommend that you do not alter any spray nozzle dimensions, as this could affect spray nozzle performance.

Material of construction

Standard materials are available as noted in this catalog. In addition, many models are available in special materials. Our technical staff will be pleased to discuss your special material requirements with you

What spray characteristics do I require ?

A spray may be characterized by describing it’s spray pattern, flow rate, atomization and spray angle. This catalog describes these characteristics for the listed nozzles, for spraying water under controlled conditions.

Spray pattern:

Common spray patterns (flat fan, full cone, hollow cone) are all described in this catalog. The spray pattern of a nozzle will generally travel further under higher fluid pressures. However, fine mist-like sprays are very susceptible to air movement, and may be carried away by such movement of air

Flow rate:

The flow rates listed in this catalog are for water in ㎖ per minute, unless otherwise indicated. “ * ” in the capacity table means “not recommended at this pressure.”

Atomization:

Atomization is primarily dependent on pressure and viscosity, and varies from point to point within a spray pattern. A range of particle sizes is produced, with some average value which varies according to conditions. For this reason, spray droplet sizes are not listed in this catalog.

Spray angles:

The spray angles listed in this catalog are for water spray under controlled conditions. Under low pressure, the sides of the spray may curve in due to the acceleration of gravity. Spray angles may also be reduced due to the tendency of spray patterns to interfere with themselves or with spray patterns from adjacent nozzles. The table below lists theoretical spray coverage for a variety of spray angles at various distances from the nozzle.

What factors will affect my spray characteristics?

When the conditions controlling spray nozzle performance change, the spray characteristics may change. This section lists conditions which may vary, and how those conditions may affect the spray characteristics.

Pressure:

The flow rate of a liquid is proportional to the square root of the pressure difference between the pressure liquid and external (usually atmospheric) conditions, thus higher pressure generally results in finer spray atomization, greater spray impact, and greater spraying distance.

Viscosity:

Spraying liquids with higher viscosity than water generally results in reduced atomization, and impact. Spray angle will usually decrease.

Specific garvity:

Flow rates shown in this catalog are for water. (The specific gravity of water is 1.0). For liquids with a different specific gravity, flow is given by the formula:

Surface tension:

An increase in surface tension generally results in an increase in spray droplet size, and a reduction in spray angle.

Spray Coverage

Refer the table of theoretical coverage below

Impact

Spray impingement, or "spray impact" as it's otherwise known, can be calculated using several different methods. The most widely used value with regards to nozzle performance is “impact per square inch.” However, it's dependent on spray pattern and spray angle. Next, using the chart to the below, find the relevant percent per square inch of the theoretical total impact and multiply this by the theoretical total. The result of this equation is the spray impact in pounds per square inch. The greatest impact in pounds per square inch is attained by solid stream nozzles and can be calculated using the formula: 1.9 x (spraying pressure, psi)

Impact per square inch

Theoretical Coverage

Note; Spray coverage in the table below are based on straight sided spray pattern. At low pressure the sides may curve in because of the acceleration due to gravity