Winterizing Your Sprayers and Plural Component Machines

Winterizing Spray Foam, Urethane, or Polyurea Machines for Prolonged Shutdowns and General Flushing of the Hose

Prior to storage, and generally whenever the spray foam, , urethane, or polyurea equipment is stored for more than a couple of weeks, the isocyanate side of the system may require a thorough flushing to prevent contamination.

When re-circulating the system frequently enough to keep the isocyanate from crystallizing is not feasible, flushing of the system will be required. Over the years, and on many occasions once the hoses have been flushed and on standby or winterized for storage, we have seen the effects of improper flushing in which contamination has occurred in the equipment, and primarily in the hoses. This is why winterizing your sprayer is so important. Be sure to keep reading about how to winterize your spray foam machine.

Reasons to Learn How to Winterize Your Sprayer

These occurrences teach us that if excessive contaminants exist after storage, there are sufficient amounts of isocyanate remaining in the system prior to storage. It is further understood that a one-time flush will not likely remove all residual materials from within the system. The assumption that a single flushing would be all that is required will consistently result in contaminated hoses.

The reasoning is best explained by understanding that the residual isocyanate remaining in the hose will react and, if not removed in a timely manner, will cling to the walls of the hose. This will be evident the next time the equipment is used. At that point, the accidental clogging of a hose section is greatly increased, making winterizing your spray equipment a priority.

Further indications have revealed that as the isocyanate is being flushed from the equipment, the operator is probably trying to reuse material that is contaminated with isocyanate or not obtaining a thorough flush in which isocyanate is either remaining or forced back through the equipment during the recycling process rather than discarding the contaminated fluid. The last flushing action must be with a clean flush through the entire system for the best results in winterizing your spray rig.

The following is a suggested procedure for winterizing your spray machine, which we recommend for flushing isocyanate out of the system and preventing any reaction of the isocyanate during the shutdown period.

The First Step to Preparing Your Spray Foam Equipment for Winter

In this part of the process for preparing your spray foam equipment for winter, you will focus on conducting an initial flush of the isocyanate side.

  • Put on all proper safety gear.
  • Turn equipment off (be sure hydraulic pressure is turned down all the way and the system has cooled to ambient temperatures).
  • Turn off the air valves on both transfer pumps and bleed the pressures on both material lines to zero PSI.
  • Prepare flush in a bucket or container
  • Place transfer pump or pick up tube in bucket.
  • Turn off resin and isocyanate supply line valves.
  • Open the isocyanate screen housing (y-strainer). Then, remove the cap and strainer.
  • Turn the transfer pump on low and flush through the y-strainer. Once the flush medium is through, shut off the pump and allow the flush to continue to drain (this will allow for an air gap within the system). Shut the material valve off and reinstall the strainer and cap.
  • Leaving the resin side supply valve in the off position, turn Iso side material valve on and turn the air on to the transfer pump.
  • Open Iso material valve at the block and pump until the air is noticed.
  • Turn off pressure imbalance features. (This feature is on most models; consult manual or manufacturer.)
  • Turn the proportioner on and turn up the hydraulic pressure until the iso side reads 500 PSI. (Resin side will remain lower. Note: In the event the resin “B” side builds pressure, simply stop, shut off the “A” side manual valve and relieve the resin “B” pressure by opening the “B” manual valve and dispense pressurized liquid in an adjacent container. Resume “A” side flush.

Step 2 of the Process for Winterizing Your Spray Foam Equipment and Extra Tips

Repeat step 1 using a clean flush to rinse through thoroughly. This will help winterize your spray rig before the cold weather causes damage.


PMC H25, 2:1 transfer pumps, ¾ inch x 20 feet transfer line, 300 feet spray hose.

Note 1: Once flushing is complete, be sure the transfer pumps are in the down position and the proportioning pump is in the retracted position. If flush and lube is not available the following, listed in order of preference, may be used. However, these substitutes contain a higher percentage of water, therefore, a greater chance of contamination can occur if the flushing procedure is not done thoroughly.


D.O.P (pump lube)

Hydraulic Fluid

Mineral Oil

Note 2: The remaining flush will contain reactive compounds within. Be sure to allow 24 hours of open-air conditions prior to sealing waste buckets.

Note 3: Do not allow frothing and air entrained flush to be pumped through the system.

Note 4: Always remove and inspect hose block and valves after prior to use after flush removal in fact removal

Learn More About How to Winterize Your Spray Machine Today

Now that you have a better grasp on how to winterize your spray rig and some tips to get started, you will be prepared for the colder months.

SprayWorks Equipment is ready to answer any questions you may have about winterizing your spray machine. Contact us to learn more.

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John Davidson is the VP of Operations at SprayWorks Equipment Group and is an SPFA PCP Certified Roofing and Insulation Installer, Roofing and Insulation Project Manager, and Supplier Rep. With over 30 years of experience in the spray foam and polyurea industry, John brings a wealth of knowledge and hands-on experience. He has worked on commercial and residential buildings, bridges and infrastructure.

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