For application where the well fluid and motor oil gravities are similar or where a well is highly deviated, a different protector design uses a “positive seal or bag” to physically separate the two fluids. See below typical of protector bag.

The positive bag protector offers a great deal of flexibility and is useful in a wide variety of applications. One area where care needs to be taken with this type of protector is with harsh well chemicals as may be experienced with treatment program. As with any oil field elastomer, care must be taken to ensure that the rubber will not be damaged by anything it will encounter in the well. Once the bag or seal is breached, the well fluid will get into the motor very easily.

ZENTEK (NX) offers ESP bags in various elastomer types material including HNBR, FFKM, Aflas and TECNOFLON. The choice of material depends on the application, in particular the operating temperature of the pump and the required chemical resistance to well fluids.