Difference in DN size and actual bore in ball valve

[NDS_21]

Hey I got a question. I can't understand why my supplier is giving me a bit different bore when I ordered a full bore ball valve design?
I got a bore of 11.6 mm in a 1/4"(DN8) full bore ball valve, 12.5 mm in a 3/8"(DN10) full bore ball valve and 24 mm in a 1"(DN25) full bore ball valve.
And in higher sizes like 2"(DN50), 3"(DN80) and 4"(DN100) the bore was 50 mm, 80 mm and 100 mm so that matches the full bore DN size values.
So is there any standard which allows the manufacturers to give these bore instead of actual full bore sizes in smaller sizes?
Or giving a bore of 8 mm in 1/4" valve is difficult considering design aspects?
Hope I defined my problem clearly.

 

[gerhardl]

For the smaler sizes valves there is quite common to see the deviations you mention. In most cases this will have no or very small practical consequences. The reasons for the deviations are often manufacturing cost/strength/machining simplifications.

(Side remark: for solenoid valves most often for instance 1/4" describes the connection pipesize, but bore could be 2mm or less)

To my knowledge there is no standard 'allowing' this. (?)

If you have ordered full bore valves (and not company X's model Y full bore, which is somewhat less) you might have a claim.

 

[Drexl]

EN 1983 specifies the minimun diameter of ball valves per DN-size/pressure class. The listed valves are all full bore.

 

[NDS_21]

oh thanks @drexl
Can you provide a picture of the table representing the minimum diameter for full bore?
Thanks in advance.

 

[MGZmechanical]

I think that according EN 17 a full bore valve is that with a bore diameter up to 90% of the nominal (DN 25 --> 22,5. DN 100 --> 90 mm, DN 200 --> 180 mm)