[dsg-svt] SVT coolant flow meter failure at 100% solenoid field

[Yuri Gotra]

Brian,

Here is what I did to debug the issue with the flow meter.

- asked Ben to help identifying components on the PCB which might be 
susceptible to magnetic field. We opened the cover, removed the LCD and 
examined the board. Ben found some sensors which might be questionable. 
Ben was skeptical about the cable routing too.

- called the manufacturer, verified that the FLR series is a spring 
piston type flow meter which could fail in the magnetic field

- following Ben's advice, borrowed a permanent magnet from Chris (target 
group)

- did a magnet test with the outlet flow meter (see photos) and verified 
that the reading fails in a field with specific direction

- did a magnet test with the inlet flow meter and verified that the 
reading fails in a field with opposite  direction (this explains why it 
did not fail although it was in a stronger field)

In the new location the flow meters will be located perpendicular w.r.t. 
their current orientation in the spot where the field is at least 10 
times less. Both factors should help in resolving the issue. Will test 
next week when solenoid will be energized.

Guess the herring was not that red after all :-)


On 11/9/17 9:27 AM, Brian Eng wrote:
> So much for it being a magnetic field issue then since the field should be lower there.
>
> As far as I can tell there isn't any information available on selection criteria, but going by the specs I don't see anything unreasonable about it (Omega FLR6302D).
>
> The manual does recommend that there should be a filter installed, but that might just be a red herring like the field issue.
>
> If I recall correctly the signal/power cable is routed differently for the sensors (the bottom one runs on the downstream side of the cart), maybe that was the issue and not the meter itself?
>
>> On Nov 9, 2017, at 9:10 AM, Yuri Gotra <gotra at jlab.org> wrote:
>>
>> Brian,
>>
>> No, the outlet one is lower by 1 foot and is further away from the solenoid. Could you please pull up the HBI documentation on selection of this model of the flow meter, re-check the specs and find out what could cause such failure. We need to figure out whether there is a safe place on the cart for normal operation of these flow meters. They could only be moved 2 feet back and 2 feet down if they stay on the cart. We could also consider a separate support cart for the chiller and the flow meters which would be located behind the CVT cart. Thank you
>>
>>
>> On 11/8/17 9:11 PM, Brian Eng wrote:
>>> Is the outlet flow meter the one that is closer to the bore?
>>>
>>> Maybe it just need to be moved further away from the fringe field? Could either go upstream or closer to the floor.
>>>
>>> Seems odd that only one of them failed, since they're identical models.

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