Newbie. Like, really new. Not stupid, just uneducated, inexperienced, and overwhelmed.

[cryojohnny]

Like the subject says, I have no idea what I'm doing. I do however, know what I want to do, and this seemed like a logical place to start.

I am a plant operator at an Air Separation plant. I would like to start working towards the maintenance and instrumentaion tech areas. I have little to no experience, other than what I've been exposed to here. My electrical is very weak. My mechanical is very strong. If it runs, I can tear it down and rebuild it, provided I don't get electrocuted to death midway through the process!

One question. Do Rosemount 3051 transmitters go bad slowly? I have been told that they either work, or they don't, so there's no need to connect them to a Fluke or Hart. The guy who told me that, has never been correct about anything related to instrumention, alarmingly enough, he's our Intrumentation Tech!!!!

Thanks.

 

[djs]

The calibration of just about any instrument can and will drift. So in that sense yes they can go bad slowly. At some point the drift will become so great that it is impossible to re-calibrate it.

 

[danw2]

The 3051 is a 'smart' transmitter. Smart transmitters are very robust. The drift in modern smart transmitters is negligible compared to their former (legacy) analog counterparts. They're so good that there really isn't provision for making a calibration adjustment other than tweaking the zero and span of the digital-to-analog converter, but most field calibrators lack the conventional "4:1 better accuracy" than the meter itself.

There are other factors that can cause a correctly calibrated DP transmitter to provide a reading that appears incorrect, like
- condensed fluid in an gas impulse tube,
- a leak in the equalizing valve in a 3 valve manifold,
- or plugged impulse tube
to name several

Heat kills electronics over time and it's the electronics that create the reading, so yeah, any overheated device can go bad.

I tend to be in the "it works or it doesn't" group, and look first for other factors when pressure transmitter readings are not up to snuff.

 

[controlsdude]

Knowing electronics

check easy stuff
Power, terminals tight, idiot lights working correctly according to manual, fuses not blown, all the easy stuff.

medium to hard stuff
Then is the instrument working according to manual, and it seems like most instruments work differently so reading the manual is mandatory. I know no one reads the manual.

hard stuff
network issues if the instrument is in a network or some signal interface to the plc or process controller.

 

[cryojohnny]

Thanks everyone. I'll try these suggestions as

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soon as I get back. Danw2, I do remember seeing a leak on one of the three valves on the block below the transmitter. So, you may be on to something.