Printer Nox on Babylog ventilator

Dear Sir/Madame

Good Day!

I have experience that expiratory tubings of Babylog ventilator turn to orange when printer nox was used as a machine to deliver nitric oxide with 20 ppm and fio2 demand of 60%. I started noticing it during the 4th day when it was connected. Have anyone experience it before? Kindly give your opinion and suggestions about it. Thank you very much.