In case this helps anyone in the future, I emailed Durgo tech support and had a very helpful reply from their Technical Manager.....
"
Hi,
Based on the pictures it looks like a DN110 valve.
You can find the dimension and year of manufacture on the top of the valve, engraved on the upper part. Your valve is rater old, based on the color, manufactured before 2010, more than 15 years old.
The DN110 valve is rated B1 according to the standard EN 12380, meaning it should be installed inline or above the appliances it serves.
Nevertheless, the A1- and B1-rated valve function is the same, the difference in rating is how it handles overpressure, especially in case of a total blockage in the drainage system.
Based on the installation point and the design of the bathroom you will clearly notice a potential total blockage in the bathtub or floor trap long before the valve will be affected.
Since the valve has likely been installed in the same location for more than 15 years, I assess the risk of future problems as very low.
For maintenance and if you experience bad smell, you might clean the valve by rinsing it in lukewarm water, don’t use strong solvents.
If you would like to replace the AAV you might consider installing a DN75 instead, almost same air flow capacity but A1-rated, allowed to be installed below flood rim.
Regards"
"
Hi,
Based on the pictures it looks like a DN110 valve.
You can find the dimension and year of manufacture on the top of the valve, engraved on the upper part. Your valve is rater old, based on the color, manufactured before 2010, more than 15 years old.
The DN110 valve is rated B1 according to the standard EN 12380, meaning it should be installed inline or above the appliances it serves.
Nevertheless, the A1- and B1-rated valve function is the same, the difference in rating is how it handles overpressure, especially in case of a total blockage in the drainage system.
Based on the installation point and the design of the bathroom you will clearly notice a potential total blockage in the bathtub or floor trap long before the valve will be affected.
Since the valve has likely been installed in the same location for more than 15 years, I assess the risk of future problems as very low.
For maintenance and if you experience bad smell, you might clean the valve by rinsing it in lukewarm water, don’t use strong solvents.
If you would like to replace the AAV you might consider installing a DN75 instead, almost same air flow capacity but A1-rated, allowed to be installed below flood rim.
Regards"
