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

There are four versions of CPS-20M for the 6270A and 2271A pressure controller.

  • CPS-20M-P3K (same as old model 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)

  • 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)
  • 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


  • TEST port (M20 x 1.5), 1/4, 3/8, 1/2 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 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) also works with 6270A and 2271A pressure controllers, is quieter in operation, and offers contamination prevention when operating at vacuum.

The below attachment contains the same information as this article.


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