yellow seals normal phase / black seals reverse phase

Please do not change from the default yellow normal phase to black on a 1290 Infinity II pump (G4220X, G7104X, G7120X). There are special valves for normal phase applications as well.   Which model pump do you have?    

But for the 1260 you can swap the seals and use either the normal phase or reverse phase seals. (G131X, G711X)

"For running normal phase applications on Agilent Infinity and Infinity II pumps, yellow PE seals are required as piston seals. By default, 1290 Infinity, 1290 Infinity II, and 1260 Infinity II Flexible Pumps use ceramic pistons and yellow PE seals as piston seals. 1260 Infinity I/II pumps use sapphire pistons and black PTFE piston seals in a standard configuration. If using black PTFE seals with normal phase applications, the black PTFE seals wear and generate small particles. Such particles can clog valves and other parts in the flow path. When running normal phase applications on 1260 Infinity I/II pumps, the piston seals have to be changed to yellow PE seals. For optimum performance, PE seals should be replaced during preventive maintenance."

See page 60 of the user's manual: 1290 Infinity II High-Speed Pumps Agilent InfinityLab LC Series User Manual

good day,

thank you for your answer

I have a model pump 7120a. I find information that this model using yellow PE seals with ceramic pistons and this system may be worked can with normal phase so and reverse phase. the will beginning problem if I change yellow seals on black seals and will use the normal phase.  ( https://www.agilent.com/cs/library/usermanuals/public/BestPractices_UnstableSolvents_TN_E ). what you write about.  I can't understand this: this system works a ceramic piston with yellow seals. if will be I using a sapphire piston with yellow seals what will be? Will the pressure not hold? I can use only the normal phase or reverse phase? Why do need PTFE seals if yellow PE seals good work how normal phase so and reverse-phase up to pressure 1200 bar? 

For the G7120 and G7104, they need to remain with the original yellow PE seals with the ceramic pistons, we don't have any other part numbers for any other seals or pistons for these pump heads.  " No modifications are necessary when using standard reversed phase applications with water and other polar protic solvents in combination with most polar aprotic solvents."  These systems will hold high pressure - Up to 130 MPa (1300 bar) at 0 – 2 mL/min ramping down to 80 MPa9800bar) at 5 ml/min

Are you seeing any issues with this setup?

Best Practices for Addressing Problems Associated With Unstable Solvents in an (U)HPLC Environment

For the G7120 and G7104, they need to remain with the original yellow PE seals with the ceramic pistons, we don't have any other part numbers for any other seals or pistons for these pump heads.  " No modifications are necessary when using standard reversed phase applications with water and other polar protic solvents in combination with most polar aprotic solvents."  These systems will hold high pressure - Up to 130 MPa (1300 bar) at 0 – 2 mL/min ramping down to 80 MPa9800bar) at 5 ml/min

Are you seeing any issues with this setup?

Best Practices for Addressing Problems Associated With Unstable Solvents in an (U)HPLC Environment

I understand.

But the question remains open. If the yellow seals with ceramic pistons maybe work how normal phase so how reverse phase then why do need

black seals and saphir pistons? in very deed the yellow seals are universal.