I am using a different evacuation cleaner and I see foam in the traps and the impeller when I clean them. Is this OK?

No, if you find foam in the traps the motor will sense the foam as liquid when it is really air. The motor will continue to try to pump it out, will lose suction power and cavitate, causing the motor to wear out much quicker than it should. Use of a nonfoaming evacuation cleaner such as ProE-Vac will protect the main motor because it will not foam in the system. Most major dental unit manufacturers now recommend nonfoaming evacuation cleaners.