Model M-21 Liquid Pump

0.33HP Liquid Pump

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Haskel Model M-21 0.33HP Air-Driven Liquid Pump

Catalog literature: Liquid Pump Catalog.pdf Acrobat DC

With a nominal pressure ratio of 21:1, the Haskel model M-21 0.33HP air-driven liquid pump utilizes a single air head to boost liquid pressures to a maximum of 2600 PSIG.

Features & Benefits:

  • Safe pneumatic operation – no heat, flame or spark risk
  • Infinitely variable cycling speed
  • Stall at pre-determined pressure to hold that pressure without consuming power
  • Problem-free stop/start applications
  • Easily automated – many modifications and control options
  • Suitable for most liquids and liquefied gases
  • Alternative gas drive options available, such as sour gas, natural gas, boil off gases, or nitrogen
  • Robust, reliable, compact and easy to maintain proven design
  • No need for air line lubrication – saves costs and prevents contamination
  • Unbalanced cycling spool provides immediate response to pressure changes
  • Can be manufactured to ATEX, CE and NACE

Technical Data:

  • Power: 0.33HP
  • Air Head: single
  • Max Air Pressure: 125 PSIG
  • Max cycles: 325/min
  • Nominal ratio (“dash number”): 21:1
  • Actual area ratio: 22:1
  • Max outlet pressure (continuous): 2600 PSIG
  • Max outlet pressure (intermittent): 2600 PSIG
  • Displacement / cycle: 0.20 cu. in.
  • Max flow: 130 cu. in./min.

Typical Performance Characteristics (@100 PSIG air supply pressure):

  • 90 in3/min @ 1500 psig
  • 48.9 in3/min @ 2000 psig

Materials of Construction:

  • Pump section: Cad-plated steel, Aluminum, SS
  • Plunger: 416SS
  • Non-metallics: Urethane, PTFE, Buna


  • Service Code 1: Petroleum-based oils, kerosene, ethylene glycol, water with 5% soluble oil.
  • Service Code 2: N/R
  • Service Code 3: N/R
  • Service Code 4: N/R
  • Service Code 5: N/R
  • Service Code 6: N/R


Repair kit information:

  • Fluid section seal kit P/N: 17179-21
  • Air drive seal kit P/N: 17178
  • Air drive seal kit (VITON seals) P/N: 29003
  • Optional tools: 55763-21 (Seal Insertion Tool)
  • Installation documents: SKIS-001