Pounds per minute of spray foam can be determined by 4 factors.
- What spray foam machine you are using vs the output it is designed to perform?
- What pressure is the spray foam being sprayed?
- What spray tip or mixing chamber is being used to spray the spray foam?
- How much spray foam can the spray foam mechanic consistently control given the spray foam application?
How the Chart Works
Using the chart below will give us the pound per minute. To the left of the chart shows us the gallons per minute. To calculate flow in pounds per minute (lbs/minute), multiply the gallons per minute (GPM) by 10 (average weight of 1 gallon of spray foam). Example: 2 GPM X 10 = 20lb/min. At the bottom of the chart gives us the pressure setting followed to the right with the most common tip sizes. Assuming we are using the #01 spray tip set at 1,200 PSI our pounds per minute is at 10. This would take 1 hour 6 minutes to empty a set of material.
It is important to note that an increase in pressure would increase the output but often times will render an uncontrollable spray pattern. This often results in over use of the products and an inconsistent profile with varying undesired depths. It is generally better to have a lower controllable output not only for maximizing the product yield but also rendering an aesthetically acceptable application.
By combining stroke counter totals from the spray foam machine (See tracking your money in yield), a determination can be made on how much time is dedicated vs. production of actual spray time.
Tight Detail Work and Small Application
When doing tight detail work and small application areas the most common tip size of choice is the #01 tip. Typical pressure settings range is 1,000 to 1,200 PSI. Using a set of foam weighing at 1,000 pounds would take 1 hour 40 minutes to empty a set. It is common to average only 6-7 pounds per minute while spraying in tight or congested areas.
Interior Spray Foam Application
When using the #02 tip used for production in interior spray foam applications set at 1,200 PSI the output would be at 15lb per minute. Assuming we are using the #01 spray tip set at 1,200 PSI our pounds per minute is at 10. This would take 1 hour 6 minutes to empty a set of material.
Exterior Spray Foam Roofing
When using the #03 tip, commonly used for exterior spray foam roofing in wide open areas with the PSI set at 1,200 PSI the output would be at 22 lbs/minute. This would take about 46 minutes to empty a set.