API Subsurface Pump Designation

The pump designation is part of API Spec 11AX and describes the main specifications of an API subsurface pump. It is a nomenclature to classify API sucker rod pumps and tubing pumps according to their main characteristics. It is comprised of seven parts, separated by dashes.
Example: 20-125-RHBC-10-4-2-2

Each part, in order, describes the following specifications:

  • Nominal tubing size (inch – given as a key representing the actual size)
  • Basic bore size (inch)
  • Type of pumptype of barrellocation and type of seating assembly (letter code)
  • Barrel length (ft)
  • Plunger length (ft)
  • Length of upper extension, used with heavy-wall barrel (inch)
  • Length of lower extension, used with heavy-wall barrel (inch)


Example: A 1 1⁄4 in. (31.8 mm) bore rod type pump with a 10 ft (3.048 m) heavy wall barrel and 2 ft (0.610 m) upper extension, 2ft (0.610 m) lower extension, a 4 ft (1.219 m) plunger, and a bottom cup type seating assembly for operation in 2 3⁄8 in. (60.3 mm) tubing, would be designated as follows:

Continue reading