Gauge block care and useage

Probably you just reached the wax point of the oil. the 5W10 had a lower wax point but would probably have gone the same way eventually.

We had an oil and transducer problem back in the 80's. A customer claimed that the transducers we were using to measure boiler feedwater flow during a steam turbine performance test were reading 1.5% low.

We were using KDG differential transducers, which used lvdt's to sense diaphragm movement in pairs of dashpots with the back sides of the pots full of silicone oil and connected via a balance pipe. They were using Rosemount transducers which had a single diaphragm between two isolating diaphragms with the enclosed spaces also filled with silicone oil. The Rosemount system measured the change in capacitance between the diaphragm and the two halves of the chamber.

Several weeks of testing showed that our transducers had lousy temperature coefficients (which we knew about and always used the transducers in temperature controlled boxes). The Rosemounts had excellent temperature coefficients. However all the Rosemounts consistently read 1.5% high when subjected to a 2300psi static pressure. This was the source of the difference, since the measurement in dispute was on a flow meter at boiler inlet pressure.

The cause of the error was simply that silicone oil is compressible and as it compresses, its dielectric content changes.

The investigation paid for itself because the error was worth $2m per 650MW turbine in 1984 money.

Mark Rand RTFM

If you are interested in taking the Mitutoyo class or just buying the 1" 3-ring binder of double sided gold - Call Patti Akram at (630) 978-6469 or a fax to the Education Dept. 630 978 6471 or email to mailto: snipped-for-privacy@mitutoyo.com The Handbook is 200 pages and contains 14 basic chapters EDU102-10 was $87.50 plus shipping.

If you take the 'basic' class - the book comes with it.

I was only able to get the book. Rats.

Martin

Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH & Endowment Member NRA Second Amendment Task Force Charter Founder

Mart> Ok here it is from my Metrology book from Mitutoyo.