Hi guys. New to the forum and first time posting. I am a civil engineer by profession but just over a year ago I started working in a laboratory for a fastener manufcturer and we have recently taken delivery of an Ascott 450+XP corrosion chamber to carry out neutral salt spray test (NSS) to BS EN ISO 9227:2006 (which is exactly the same as ASTM B117).

We are currently trying to achieve accreditation through UKAS and we have just recently had our preliminary visit from them where they pointed out a few things we need to correct before their next visit in November.

Anyway, my question is: does anyone here know anything about corrosion chambers? As this is my first experience in working with them I am only beginning to learn about them and a problem I seem to having is the pH of the fallout collected in external containers seems to become a lot more acidic than when it originally went into the chamber from the reservoir. pH of the reservoir before entering was 6.9 (should be between 6.5 & 7.2) however, when it exits the chamber and collects in the external collectors the pH has dropped to closer to 5.

I am guessing that this change in pH is caused by the atomisation of the salt water solution upon entering the chamber and possibly the internal chamber temperature (35C) but I am not 100% certain. So if anyone here can shed some light on the matter for me I would very much appreciate it.

Many thanks in advance.