How to Choose A Spray Gun Fluid Nozzle Size

Spray Gun Fluid nozzles control the amount of coating you can apply at a given time with your spray gun. They also determine the thickness of coating you can apply without thinning when using a gravity fed spray gun. Essentially choosing the proper fluid nozzle will help to reduce paint waste and ensure you apply the appropriate amount of coating for your product’s needs. The goal of this article is to provide a guide on how you can choose the right fluid nozzle for your spray gun

How to Find the Right Fluid Nozzle for Your Spray Gun

•  With any technical data sheet that comes with coatings their should be a recommended spray gun fluid nozzle size range. This will help to give a rough estimate of the right fluid nozzle.
• Typically pressure fed spray guns will use a smaller fluid nozzle than suction (the suction nozzle will be 0.015 – 0.020 sizes bigger which means the next size up in fluid nozzles
• With the service manual that comes with most spray guns there will be a chart showing fluid nozzle sizes and which size fluid nozzle and what size air cap is recommended for various coatings 
• If you are not able to keep up with production or having to make numerous passes you should consider the next largest fluid nozzle or if your coating is getting runs in it then consider a smaller fluid nozzle.

Calculators to determine the exact size fluid nozzle for your Paint Gun enter highlighted cells information only

Calculator 1 is based on percent solids of material if you do not have a technical data sheet available

Step 1 Perform a Flow Rate Test if using a spray gun if considering an airless or air assist airless use the chart at the bottom of the article

•  A Flow Rate Test is when you turn off all atomization air to your spray gun and trigger the spray gun while catching the paint being dispensed for 60 seconds. You then should have how many ounces per minute of coating your dispensing. You can use one of the two calculators below.

This first calculator is based on percent solids that is in your coating the second is based on square feet of coverage specified in your coatings technical data sheet.

1.  Measure All Surfaces to be painted in feet and enter in length and width section or use this calculator and determine total square feet to put into box by inputting length and width of all surfaces to be painted (you can use inches in this calculator in addition to feet)
2. Enter Your Coatings Percent Solids in decimal form (remember to adjust percent solids based on any thinner being added consult this chart for info on thinner added and the percent solids that will result)
3. Enter Your Paint Equipment’s Transfer Efficiency, you can review transfer efficiency of paint equipment here
4. Enter Dry Film Goal DO NOT ENTER WET FILM IT IS CALCULATED BASED ON PERCENT SOLIDS OF MATERIAL
5. Enter Time you want to complete your product in and you will receive FLUID FLOW RATE
6. Take FLUID FLOW RATE AND FIND APPROPRIATE FLUID NOZZLE or Consider Airless if Higher Production Needed (see chart below to see GPM of nozzles using airless Paint Sprayer) remember if you change to an airless unit or a different type of spray gun (conventional vs HVLP) you will have to recalculate the fluid rate needed because transfer efficiency will be different

Calculator 2 uses Square feet of coverage of your coatings from a technical data sheet

Enter all highlighted cells using the information from your technical data sheet to determine fluid rate needed. Perform flow test with spray gun to determine proper fluid nozzle size.  Doesn’t include any added thinner .

GPM of Airless Based on Tip Size

Remember just because a given fluid nozzle will provide a certain production rate you will have to test the spraying of the coating to make sure you can achieve your desired finish quality requirements given the fluid nozzle size.

Further Resources

Devilbiss Fluid Nozzle Selection Guide Tool – Devilbiss provides fluid nozzle recommendations for all the major automotive coating manufacturers for their spray guns.

Automotive Tip Size General Guide

If you need further help meeting your production needs and fluid nozzle give us a call and will help