Absolutely amazing overview, the manual is rather dense and doesn't really have a good eli5 description of the operating principle so this helped immensely.
Thanks this vid helped alot. The span can also be adjusted in the top left hand corner of the box where 2 screws attched to the back plate can be loosened so it can be moved, moving the flapper from side to side adjusting the point where the nozzle from the bourdon tube meets it. This changes how much the flapper has to move before its creating backpressure within the bourdon tube. Just one point that was missed but otherwise this was great thanks
@neild123456 What I'm saying is that if the liquid's SG changes, it changes the proportionality between level and buoyant force. Take the "thought experiment" of the SG suddenly doubling: you would have twice as much buoyant force for any given amount of level surrounding the displacer. Not just an added amount of force, mind you, but a *multiplier* of twice. This is why displacer-type level instruments are useless if the liquid SG is known to randomly change.
@neild123456 As a general rule, any factor that has a "multiplying" or "dividing" effect shifts the span, while any factor having an additive or subtractive effect shifts the zero. Since a change in fluid density (SG) does indeed have a multiplying effect, it requires a span compensation. Try a thought experiment to prove it to yourself: what would happen if the liquid's SQ suddenly doubled? Would this double the buoyant force at any given level, or would it merely add some force?
I’m an instrumentation student, this was super helpful!
Absolutely amazing overview, the manual is rather dense and doesn't really have a good eli5 description of the operating principle so this helped immensely.
Thanks this vid helped alot.
The span can also be adjusted in the top left hand corner of the box where 2 screws attched to the back plate can be loosened so it can be moved, moving the flapper from side to side adjusting the point where the nozzle from the bourdon tube meets it. This changes how much the flapper has to move before its creating backpressure within the bourdon tube. Just one point that was missed but otherwise this was great thanks
@neild123456 What I'm saying is that if the liquid's SG changes, it changes the proportionality between level and buoyant force. Take the "thought experiment" of the SG suddenly doubling: you would have twice as much buoyant force for any given amount of level surrounding the displacer. Not just an added amount of force, mind you, but a *multiplier* of twice.
This is why displacer-type level instruments are useless if the liquid SG is known to randomly change.
Great video!!👍
@nugz125 Thanks for the informative comment!
GOOD EXPLANATION
What we're looking at here is a Fisher level trol it's a displacer type level instrument we've got it set up on this rack just for a
@neild123456 As a general rule, any factor that has a "multiplying" or "dividing" effect shifts the span, while any factor having an additive or subtractive effect shifts the zero. Since a change in fluid density (SG) does indeed have a multiplying effect, it requires a span compensation. Try a thought experiment to prove it to yourself: what would happen if the liquid's SQ suddenly doubled? Would this double the buoyant force at any given level, or would it merely add some force?
thats not your span adjustment