2 phase liquid/gasseous helium flowmeter 2

[iainuts]

Anyone ever heard of a flow meter that handles 2 phase liquid helium? (ie: liquid and gasseous helium)

 

[dcasto]

only a coriolis meter could be used.

 

[ione]

You can go through the thread below to get further details

http://www.eng-tips.com/viewthread.cfm?qid=179677&page=1

 

[ione]

If I may add

 

[iainuts]

Thanks for the feedback. I've heard of the Micromotion meters but not heard anything good about them. I emailed someone I know that had 6 of them installed for gasseous helium service at 4 K. Here are his remarks:

These have been troublesome. We have had reliability problems with these, which we have suspected is related to the cold. We lack the mentioned modification to the internal wire gauge – that may be our problem. It’s odd that no one at Micro-motion mentioned the wire gauge mod when they attempted to investigate our failures.

We do have the helium purge. (Micro-motion insisted, despite my objections, that they would work fine with a nitrogen purge; but that was wrong, they did not work. Micro-motion did them over with helium.) Perhaps the knowledge gained on the CERN project has been lost to them.

We have also had a great of trouble getting a consistent calibration on these meters.

I have not tried these on liquid helium. They are not vacuum jacketed.

After having trouble with these we have been very reluctant to apply them elsewhere. They are very expensive and if they fail Micro-motion will usually not repair them. They want you to buy a new one.

Sounds like Micromotion needs to get their s*** together.

 

[dcasto]

first off, their maybe a dozen places on earth where they need to measure ;iquid helium, so finding a meter specialized for such a market is tough enough.

Next, you need to adjust the output of the reading for the speed of sound in the fluid, How many people can even tell you what the density of helium is at 4K let alone the speed of sound.

You can not calibrate a micromotion, nobody can. They have to be calibrated in a lab and the cubic equation that is used to convert the frequency to an infered mass must be entered. In the field you'd need at least 10 data points at various densities and rates to get the calibration factors.

You wanted a two phase flow meter, there is no DP or positive displacement meter that can do this. a velocity meter won't work, there is nothing except micromotion that can get close to measuring two phases.

I'm not a salesman for micro-motion, but I installed my first one in the late 1970's and have forgotten more about them than the average MM sales guy learns.