How do I know if there is air in the feed hose?

Air in the feed hose affects spray results and must be avoided. But how can you recognize it?

Air in the feed hose of your spray foam system will lead to bad spray results. To avoid it, you must know how to recognize air in the feed hose. Your Graco Reactor can help you avoid unwanted air entering your system.

You should avoid air bubbles in your system at all times, as they lead to off-ratio issues and bad spraying results. Recognizing air in the feed hose is relatively simple.

When air is present in the feed hose of your spray foam or polyurea system and travels through the pump, it will produce a loud “knocking” sound. The inlet pressure gauge will be dampened, indicating a pressure drop in the system.

What causes air bubbles in the system?

There are several possible causes of air bubbles in the feed hose:

  • A leaking feed pump
  • Empty material drums
  • An erroneous material drum change

In the figure below you can see how the ratio remains 1:1 until a resin drum change introduces air into the feed hose. As the air remains trapped in the Reactor, you will see ratio spikes and offsets.

How to avoid air in your system?

The main cause of air entering the system is an empty material drum. So, an easy way to avoid air in your feed hose is preventing the material drums from running completely empty and shutting down the system in time.

Graco Reactors can automatically detect low drum levels and shut down the system when a pre-set minimum level is reached. To use this functionality, enter current drum levels in the ADM (Advanced Display Module) of your Reactor. For more information, please see manual 333023P, Search for “Maintenance Screen”.

Refer to the manual for further directions:

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