oils a straight gravity separation chamber a shaft tube 13 and a shaft seal 15 may be used to prevent the shaft 17 from imparting rotation to the fluids in the chamber 11 this may avoid mechanical mixing of the pfpe oils with the well fluids thereby preventing centrifugation of the pfpe oils out of the top of the chamber 11 because pfpe oils are much denser than the well fluids the shaft seal 15 may no longer be critical because any well fluids that leak into the protector 16 may not sink down through the pfpe oils to the motor 14 when the motor 14 heats up the levels of the rite oils rise when the motor 14 cools the levels of the pfpe oils fall thus the well fluids may be effectively separated from the pfpe oils due to the unique physical properties of the pfpe oils such as high specific gravity and immiscibility with well fluids 4 pfpe oils may be used to exclude well fluids and to pressure balance potheads with motors and protectors in relatively vertical wells at any temperature because of their high specific gravity in accordance with embodiments of the invention the potheads may feature oil tilled metal tubes that can be welded to the top end of the potheads and extended over the cables up past the top end of the protectors these metal tubes may serve to pressure balance the protectors and the motors fig4 shows a pumping system illustrating a pothead attached to a motor in accordance with one embodiment of the invention as shown a submersible centrifugal pump 12 may be operatively coupled.