7 Daily Habits That Keep Your Plural-Component Proportioner Spraying

Plural-component proportioners are tough machines, but they’re also precise ones. Two materials have to arrive at the gun at the right pressure, the right temperature and the right ratio — every second you’re spraying. When something drifts, you get off-ratio material, wasted drums and callbacks. The good news: most problems give warning signs long before they stop the job. These seven habits help you catch them.

1. Check the ISO pump lubricant before every job

The isocyanate (A-side) pump uses a lubricant reservoir or wet cup to keep isocyanate from curing on the pump rod. Look at it every morning. Clean, clear lubricant is what you want. If it’s cloudy, discolored or starting to gel, isocyanate is getting past the throat seals.

2. Inspect inlet strainers and Y-screens

Inlet strainers protect your pumps from debris, crystals and skins that form in drums. A partially packed screen starves a pump and causes pressure imbalance. Make checking them part of every drum change, and keep spare screens on the truck — a 60-mesh Y-strainer screen costs far less than a pump rebuild.

3. Log pressures and temperatures at start-up

Write down A and B pressures, primary heater and hose temperatures, and drum levels when you start spraying and again mid-day. A simple log turns “it’s been acting weird” into data: you’ll see a slow pressure split or a hose that takes longer to reach temperature long before it becomes a failure.

• Pressures should stay close to each other while spraying.
• Heaters should reach set point in a consistent amount of time.
• Note ambient and substrate temperature — they change how material behaves.

4. Keep moisture away from the isocyanate

Isocyanate reacts with water vapor in the air and forms crystals. Those crystals plug screens, score pumps and destroy seals. Use a desiccant dryer on the A-side drum vent, keep drums sealed between jobs, and never leave the A-side open to humid air.

5. Make sure transfer pumps can keep up

Your proportioner can only spray what its feed pumps deliver. Check that transfer pumps are cycling smoothly, that materials are mixed and at the right temperature in the drum, and that supply hoses aren’t kinked. A tired transfer pump is a common cause of B-side pressure drop — rebuild kits like the GHO transfer pump rebuild kit are worth keeping in stock.

6. Grease and clean the gun every shutdown

Whether you run a Graco Fusion, a Probler P2 or a PMC Xtreme, a few seconds of care at shutdown pays off. Clean the face of the gun, grease it according to the manufacturer’s instructions, and store it so the mix chamber can’t cross over overnight. Use the Parts Finder to find the exact seals and o-rings for your gun.

7. Park the pumps and relieve pressure at the end of the day

Follow your machine’s shutdown procedure: park the pumps so the rods aren’t left exposed, turn off heat, and relieve system pressure. Parking protects the ISO pump rod from curing isocyanate, and relieving pressure makes the next start-up safer and more predictable.

Printable daily checklist

1. ISO pump lubricant clean and at level
2. Inlet strainers and Y-screens clear
3. Start-up pressures, temperatures and drum levels logged
4. Desiccant dryer installed and drums sealed
5. Transfer pumps cycling smoothly
6. Gun cleaned and greased at shutdown
7. Pumps parked, heat off, pressure relieved

Want help setting up a maintenance routine for your rig? Call a technician at (417) 831-5090.

Always follow the operation and maintenance manual for your specific equipment. This article is general guidance and does not replace manufacturer instructions.