Speeding Up Production – Equipment Sizing & Tips
Written by Tim Simpson, Quality Assurance and Quality Control Manager, Maintenance Coatings Inspector
Occasionally it’s better to have larger equipment, and sometimes it’s better to size down. There are a variety of reasons for this. Here are a few:
High-pressure airless equipment atomizes coating materials and, in the process, can create airborne paint fog downwind of the application. There are ways to size equipment to reduce this fogging. A high capacity airless sprayer with the ability to move a higher volume of material at a lower pressure can enable you to use larger tips while at the same time reducing the fogging by-product of the spray process. Pump ratios come into play when planning out your equipment. For example, a 45:1 ratio pump could pump 4+ GPM of material at the range of 2,500 to 4,500 psi. A 60:1 ratio pump could pump 3+ GPM at up to 6,000 psi. The 60:1 ratio pump would be overkill for your project.
The goal in this situation is to deliver the most material to your rooftop through your spray lines to attain the desired product with minimum negative side effects such as overspray damage. As a result we go with mid-sized airless equipment on roofs that can achieve between 1.0 GPM minimum and 4 GPM maximum at the lower pressure ranges. Our tips’ sizing can be larger this way with lower pressures at the tip thereby reducing overspray.
Being able to dial down our output pressures at the pump means we can also use lower flow rates and tip pressures to spray a bed coat of Ames Super Elasto-Barrier during the fabric embedding process when appropriate and keep the fabric wet as the embedding roller person is doing his final embedding roll along the Fabric Train. An added plus is that the team moving across the deck embedding fabric does not have to replenish roller or dump buckets since the spray man is right there with an endless supply of material. This becomes even more important when trying to set down a bucket of material on a domed or high sloped roof, which can result in spills. When a spill happens the whole production train stops.
Caution: It requires a good spray technician to properly aim his spray pattern to avoid wrinkling fabric, billowing fabric, etc. Less pressure is ideal even if the spray pattern is fingering or tailing a bit. It does not matter as all the material in this process is also getting rolled during the embed part, which evens up the material. Skill, technique, and team cooperation using this process can create amazing high-production results.
Sometimes a gun needle will malfunction and not return properly to its seat when you let up on a sprayer. This can happen frequently on a spray gun/wand assembly. Debris can hang up between the needle and seat, spraying full bore with no place to run.
Here’s a solution: Have a high-pressure ball valve installed in the line where the airless line is trailing across the roof where it can be readily accessed by the rooftop crew. When the gun sticks open, notify one of your rooftop men to shut off the material at the rooftop ball valve. This will stop the pump from continuing to cycle material up through the malfunctioning gun and allow you to lower the gun and wand back down to the pot tender. The pot tender will then shut the pump down, notify you to re-open the rooftop line ball valve, and then the pot tender will clear the obstruction, flush the line if necessary and get you back up and running quickly. Complications are kept to a minimum and the production train rolls on.