Bore of a standard Isolator

[frank999]

Using this cheap imported tat as an example:
http://www.screwfix.com/p/15mm-isolating-valve-pack-of-2/65251

Cant find any bore dimensions any where, looking at the orifice it appears to be reduced to about 10mm in size, does that sound correct.

With reasonable water pressure that shouldn't restrict water too badly ?

Found this:
http://www.tlv.com/global/TI/calculator/water-flow-rate-through-orifice.html
Assume secondary pressure will be virtually same, this tells me a 10mm bore at 4 bar will fill a 100 litre tank in approx one minute - does that seem plausable, seems very fast ... or have I got this wrong ...

Thanks

 

[Dan Robinson]

You're missing a lot of data for such assumptions.

 

[frank999]

Thanks, the app. has an advanced option, is the 'simple' option just a gimmick not to be taken seriously ?

I need to calculate cold water flow through a 4.5mm bore orifice, on mains water pressure (assuming 3-4 bore), any reliable pointers/tables I can reference.

 

[Burnerman]

Absolutely no idea about any reference tables or whatever, but if the volume of water needed is important (outside hose etc) then fit a full bore lever arm isolator.
John

 

[Jackrae]

Is this a water turbine driven from the town mains type job

 

[frank999]

I guess water pressure plays a reasonable part in the rate of flow ?

 

[Jackrae]

I guess water pressure plays a reasonable part in the rate of flow ?

That's putting it mildly
Basically flow through an orifice is a proportional to the square root of the upstream pressure. That might not sound too intuitive but eventually the flow becomes "choked" ie flow rate does not increase proprtionally to the pressure causing it.

 

[frank999]

Yes, thats makes sense, sure there is a lot of science involved ... maybe bit of Googling and YouTubing is in order to better understand

 

[muggles]

The bore of the valves you've linked to is approx 7mm