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CPS-20M Test Port O-Rings (Contamination Prevention System, 20 MPa)

CPS-20M is no longer available and has been replaced by CPS-40M. CPS-40M is compatible with all products that specify CPS-20M as an available accessory. 

There have been five versions of CPS-20M for the 6270A and 2271A pressure controllers.

  • CPS-20M
  • CPS-20M-P3K (same as CPS-20M but with added LED)
  • CPS-2270-20M-P3K
  • CPS-20M-HC20
  • CPS-2270-20M-HC20

Two types of TEST ports are used.

P3000 Style (P3K)

  • Test port style that has been available since the launch of the CPS
  • CPS has a male test port with reverse threads
  • Supplied with 10 adaptors: NPT, BSP and metric (PK-ADPTR-P3K). Does not require PTFE tape or tools
  • Same test port is used on the P3000 deadweight testers and P5500 pressure comparators


Item   PN Viton    Description
  1       3865163      O-ring for use with 1/8 inch adapters
  2       3919892      Test Port Insert for use with 1/8 inch adapters
  3       3865195      O-ring 

HC20 (Hand tight Connection, 20 MPa/3000 psi). This test port should not be used and needs to be replaced by a HC20 to HC40 upgrade kit. Contact Fluke Calibration Technical Support for information. Contact by the link at the end of this article, by emailing or by calling +1-877-355-3225.

  • CPS has a female, swiveling connection that is M20 X 1.5
  • Supplied with 9 adaptors: NPT and BSP (1/8, 1/4, 3/8 & 1/2) and M14 x 1.5 (PK-ADPTR-HC20). The thread on the bottom of all adapters is M20 X 1.5.
  • Seals on o-rings, PTFE tape and wrenches are not required
  • Easier to operate with NPT fittings. The adaptor can be attached to the gauge, placed facing forward on the test port, and then the swiveling connection is turned to tighten the gauge
  • Adapters are compatible with CPS-40M but are only rated to 20 MPa / 3000 psi


  • TEST port (M20 x 1.5), 1/4 inch, 3/8 inch, 1/2 inch and M14 x 1.5 adapters use this o-ring

                 3865195 (54-703-10),O-RING VITON 1/4 X 1/16 X SEC

  • 1/8 inch adapters use this o-ring

                 3865454, Qty 2 O-RING,FKM,VITON,.070IN W,.114IN ID,75 DURO,BROWN,SIZE 2-006

See the 6270A Service Manual for less often used parts

See this article for CPS-20M Maintenance, CPS-20M Maintenance

Note: The CPS-40M (40 MPa model) is the replacement for CPS-20M and is for use with 6270A and 2271A pressure controllers. It is quieter in operation and offers contamination prevention when operating at vacuum.


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