The convertible rotary seal has a housing for receiving the polishing rod. A mandrel is rotatably mounted in the seal housing and surrounds the polish rod. A wear sleeve surrounding the mandrel engages a primary seal. A secondary seal engages the mandrel and polish rod and rotates therewith but may be converted for use as a static seal if necessary. A locking mechanism selectively secures the mandrel in a stationary orientation with respect to the seal housing. Fluid that leaks past the primary seal will be detectable through an external orifice. If a leak in the primary seal is detected via the external port, then the mandrel may be secured in a stationary orientation with respect to the housing and the secondary seal may be reconfigured to operate as a stationary seal until such time as the rotary sealing unit can be overhauled.

A seal, such as a Polypak seal, is received in the tapered upper chamber of the rotating spindle. The Polypak seal has an inside diameter and an outside diameter. The Polypak sealing gasket is communicated with the upper surface of the Polypak seal and the upper conical cavity of the rotary spindle.

PolyPak seal is an extruded seal with symmetrical profile and high sealing performance under low pressure. The standard PolyPak seal uses a straight cut scraper lip design formed by a precision finishing process. With the increase of system pressure, additional force is applied to the sealing interface of PolyPak. With the continuous increase of pressure, the lip load will automatically increase to compensate for this higher pressure, so as to maintain a positive leak free seal from hard vacuum to 60000 psi or more through appropriate design and auxiliary devices.

In addition to providing excellent sealing in vacuum, low pressure and high pressure applications, PolyPak seals have many advantages over traditional symmetric or asymmetric u-cup seals, including:

• Its o-shaped spring excitation device can stably seal under extreme pressure, preventing the deformation of the sealing lip and rolling or twisting in the gland.

• Under extreme conditions of low or high temperature, the o-spring maintains the lip load on the inner diameter and outer diameter of the sealing interface.

• PolyPak seals can be stretched or extruded to accommodate oversized cylinder bores and undersized rods. PolyPak will compensate for and maintain the appropriate lip load as long as the seal cross section is the correct size relative to the radial groove.

• The range of materials available ensures the correct combination of wear, extrusion, temperature resistance, fluid compatibility, high sealing and long life.

We can use a primary seal and an auxiliary static seal to improve reliability. Accessible external ports provide early warning before the primary seal fails. If the primary seal fails, the secondary seal can be converted to avoid accidental shutdown of the pumping system. The secondary seal system operates as a traditional stuffing box using PTFE and graphite packing and can be used until maintenance events can be scheduled, thus avoiding costly additional downtime.