BIZOMAT MAKEOS · Hydraulics
Nozzle Manifold Check (Flow per Nozzle, Total Flow, Feed Pipe Loss, Supply Pressure)
For a row of spray or wash nozzles fed by one pipe, how much flow do they take at the nozzle pressure, what is the pressure loss in the feed pipe, and can the pump supply it?
Check of a nozzle manifold or spray bar: the flow through each nozzle from its orifice size, discharge coefficient and pressure (as the orifice flow tool), the total flow, the velocity, Reynolds number, friction factor and pressure drop in the feed pipe with fittings taken at the full flow (as the pipe friction tool), and the supply pressure needed, against the pump pressure available and a velocity limit.
Open the calculatorRuns in your browser. No account needed.
How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Number of nozzles | nozzles | Number of nozzles on the manifold. |
| Nozzle orifice diameter | mm | Orifice diameter of each nozzle. |
| Discharge coefficient | Discharge coefficient of the nozzle (from the nozzle maker; about 0.6 for sharp orifices, higher for shaped nozzles). | |
| Pressure at the nozzles | bar | Pressure wanted at the nozzles. |
| Liquid density | kg/m³ | Density of the liquid. |
| Feed pipe | ||
| Pipe inside diameter | mm | Inside diameter of the feed pipe. |
| Pipe length | m | Length of the feed pipe from the pump to the last nozzle. |
| Kinematic viscosity | cSt | Kinematic viscosity of the liquid (1 cSt for water at 20 °C). |
| Pipe roughness | mm | Absolute roughness of the pipe. |
| Fittings loss coefficient (total) | Sum of the loss coefficients of bends, valves and fittings. | |
| Supply | ||
| Pump pressure available | bar | Pressure the pump gives at this flow. |
| Largest pipe velocity | m/s | Highest velocity you accept in the feed pipe. |
What each input means
Open an input to see what it is, its units, the worked example and the common mistakes, with a small diagram.
What this means: Number of nozzles
- What it is
- How many identical nozzles the manifold feeds at the same time.
- Units and format
- Enter a number in nozzles: nozzles. The form accepts 1 nozzles to 1000 nozzles. Use a whole number. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 6 nozzles as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Total flow rises in direct proportion, which raises pipe velocity and pressure loss.
- Get it right
- Count only the nozzles that spray together; closed or spare outlets do not draw flow.
What this means: Nozzle orifice diameter
- What it is
- The diameter of the smallest opening in each nozzle, where the jet leaves.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 100 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 2.5 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Flow per nozzle grows with the square of the orifice diameter.
- Get it right
- Use the orifice size from the nozzle maker; worn nozzles open up and pass more flow.
What this means: Discharge coefficient
- What it is
- The ratio of the real flow through the nozzle to the ideal flow through the same opening, allowing for jet contraction and friction.
- Units and format
- Enter a plain number with no unit. The form accepts 0.1 to 1. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.8 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Flow per nozzle rises in direct proportion to this coefficient.
- Get it right
- Take it from the nozzle maker’s flow data for that nozzle type.
What this means: Pressure at the nozzles
- What it is
- The gauge pressure you want just upstream of the nozzles, which drives the liquid out through each orifice to atmosphere.
- Units and format
- Enter a number in bar: bar (1 bar = 100 kPa). The form accepts 0.000001 bar to 1000 bar. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 3 bar as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Flow per nozzle grows with the square root of this pressure.
- Get it right
- Use gauge pressure; the tool adds the feed pipe loss to it to find the supply pressure.
What this means: Liquid density
- What it is
- Mass per cubic metre of the liquid being sprayed. It sets jet velocity for a given pressure and the pressure lost in the pipe.
- Units and format
- Enter a number in kg/m³: kilograms per cubic metre. The form accepts 0.000001 kg/m³ to 25000 kg/m³. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 1000 kg/m³ as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Use the density at working temperature from the liquid’s data sheet.
Feed pipe
What this means: Pipe inside diameter
- What it is
- The bore of the feed pipe that carries the total flow from the pump to the nozzles.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 5000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 20 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A smaller bore raises velocity and pressure loss sharply.
- Get it right
- Use the actual inside diameter for the pipe schedule or tube wall, not the nominal size.
What this means: Pipe length
- What it is
- The length of feed pipe from the pump to the last nozzle. The tool assumes the full flow travels the whole length.
- Units and format
- Enter a number in m: metres. The form accepts 0.000001 m to 100000 m. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 6 m as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Friction loss in the straight pipe rises in direct proportion to length.
- Get it right
- Measure along the pipe route, including vertical runs and branches to the manifold.
What this means: Kinematic viscosity
- What it is
- The kinematic viscosity of the liquid at working temperature, used to find the Reynolds number and friction in the pipe.
- Units and format
- Enter a number in cSt: centistokes (kinematic viscosity, 1 cSt = 1 mm²/s). The form accepts 0.000001 cSt to 100000 cSt. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 1 cSt as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- cSt equals mm²/s; take it from the liquid data sheet at the actual temperature, as viscosity changes strongly with temperature.
What this means: Pipe roughness
- What it is
- The average height of the roughness on the pipe’s inside wall, used in the friction factor for turbulent flow.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0 mm to 10 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.045 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Take it from a pipe-flow reference for the pipe material and condition; old or scaled pipe is rougher than new.
What this means: Fittings loss coefficient (total)
- What it is
- The sum of the loss coefficients for every bend, tee, valve, strainer and entry in the feed line, each multiplied into velocity head.
- Units and format
- Enter a plain number with no unit. The form accepts 0 to 1000. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 4 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Fitting loss rises in direct proportion to the total coefficient.
- Get it right
- Add the coefficients of all fittings in the line from fitting maker or pipe-flow reference data.
Supply
What this means: Pump pressure available
- What it is
- The gauge pressure the pump delivers at the total flow, read from the pump’s performance curve. It is compared with the supply pressure needed.
- Units and format
- Enter a number in bar: bar (1 bar = 100 kPa). The form accepts 0.000001 bar to 1000 bar. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 4 bar as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Read the curve at the total flow the tool reports, not at the pump’s best efficiency point.
What this means: Largest pipe velocity
- What it is
- The highest average liquid velocity you accept in the feed pipe, to limit noise, erosion and water hammer.
- Units and format
- Enter a number in m/s: metres per second. The form accepts 0.000001 m/s to 50 m/s. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 3 m/s as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Set it from your piping design rules or the pipe supplier’s guidance.
Method and formulas
- Flow per nozzle Q = C_d A √(2Δp ÷ ρ) (as the orifice flow tool); total = nozzles × flow.
- Pipe drop = (f L ÷ d + ΣK) ρ v² ÷ 2 with f from Colebrook or 64 ÷ Re (as the pipe friction tool), at the full flow over the whole length.
- Supply pressure = nozzle pressure + pipe drop.
- Example: 34.629 L/min in total; the pipe loses 0.20881 bar, so 3.2088 bar is needed.
Limitations
- Full flow taken over the whole pipe length, which is on the safe side for a manifold that feeds nozzles along its length.
- Equal pressure at every nozzle; long manifolds give less at the far end.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Size the feed pipe for a spray bar
- Check a pump for a parts washer
- See how many nozzles a supply can feed
Who it is for
- Process engineers
- Maintenance engineers
- Machine designers
What you get
- Flow per nozzle and in total
- Feed pipe velocity and pressure drop
- Supply pressure against the pump
Interpreting the result
- Nozzle flow rises only with the square root of pressure: doubling the flow needs four times the pressure.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 3024–3027, 352–368. Topic reference; no source tables or recommended settings are reproduced.
BIZOMAT tools are screening and decision-support utilities. Verify important financial, engineering, safety, legal or operational decisions using appropriate professional standards and your organisation’s approved data.