Mean time To fail in Pressure Gauges?
Mean time To fail in Pressure Gauges?
(OP)
Hello fellow colleagues.
Since a 4 years of growth, construction & startup of a new production lines in our fine chemical facility the engineering department will be focusing in improvement projects.
I detected increasingly failures in pressure gauges. After some investigation we found out we are replacing 200 manometers per year of a total of 1000. I'm going to start a plant installation review in a couple of days, based on best practices and the provider comments.
So I want to ask you about your thoughts, and experience in your plants.
What would you say it's a mean time between failures on manometers (I understand it totally depends in the application) is there any average? What number will be ok? Any recommendation that you can share with me? Any further reading or technical information that you could share?
Thank you very much.
95 % of our PG are from 0 to máximum of 7kg/cm2, 0.5% to 1% error, 4.5 in dial, plastic enclosure, SS burdon%conection.
Since a 4 years of growth, construction & startup of a new production lines in our fine chemical facility the engineering department will be focusing in improvement projects.
I detected increasingly failures in pressure gauges. After some investigation we found out we are replacing 200 manometers per year of a total of 1000. I'm going to start a plant installation review in a couple of days, based on best practices and the provider comments.
So I want to ask you about your thoughts, and experience in your plants.
What would you say it's a mean time between failures on manometers (I understand it totally depends in the application) is there any average? What number will be ok? Any recommendation that you can share with me? Any further reading or technical information that you could share?
Thank you very much.
95 % of our PG are from 0 to máximum of 7kg/cm2, 0.5% to 1% error, 4.5 in dial, plastic enclosure, SS burdon%conection.





RE: Mean time To fail in Pressure Gauges?
It could be as simple as having replaced the original quality gauge with an inferior gauge and the inferior product just doesn't hold up.
Some of the things people look at for increasing pressure gauge lifespan are
- doing a forensic on what (and presumably, why) a given gauge in a given location failed, so you have a baseline knowledge to work from in deciding on an alternative
- examining the actual gauge construction - Like my father said, "there's nothing someone can't make cheaper".
- remounting gauges with impulse tubing, capillary or extensions to address temperature failures
- adding snubbers to limit hydraulic shock
- liquid fill - lubricates the movement as well damps some vibration
- seals for corrosion issues
- using a more robust construction, like a helical tube
- training class for the wrench twisters to increase their awareness of the delicate nature of a pressure gauge.
Some vendors, like the German Wika, clearly target the high end user who values quality and understands life cycle cost vs purchase price. They even have a video on 'top 7 reasons gauges fail'.
http://wika-fast.com/best-practices-animation/
RE: Mean time To fail in Pressure Gauges?
I have long ago come to prefer Dwyer Magnehelic gages to u-tube manometers where they make sense.
It's fairly common to install a damper on the gage stem where pressure changes fast, or to use a 'press to read' valve that keeps the gage isolated and vented except when taking a pressure reading. I can't tell from here if either makes sense in your applications.
Mike Halloran
Pembroke Pines, FL, USA
RE: Mean time To fail in Pressure Gauges?
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RE: Mean time To fail in Pressure Gauges?
In both cases an appropriate restriction installed ahead of the gauge can often be all the protection needed.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Mean time To fail in Pressure Gauges?
In your experience how much time could a manometer be in operation with out failing, if installed in a correct application.
Dawn2:
I read al wika information it will be put in good use. Thx.
RE: Mean time To fail in Pressure Gauges?
Mike Halloran
Pembroke Pines, FL, USA
RE: Mean time To fail in Pressure Gauges?
Somthing like this.
http://www.wika.us/23x_34_en_us.WIKA.
RE: Mean time To fail in Pressure Gauges?
I use the word manometer for something else, generally a liquid filled u-tube, or a pressure gage with equivalent range, usually 0 to a meter or less of liquid column.
As mentioned, pressure gages are usually protected from surge/shock by isolation valves or dampers. If your facility doesn't use something like that, do start.
Do also examine any replaced gages you can acquire, to find out why they failed.
Mike Halloran
Pembroke Pines, FL, USA
RE: Mean time To fail in Pressure Gauges?
RE: Mean time To fail in Pressure Gauges?
Roy
RE: Mean time To fail in Pressure Gauges?
Hi Luis,
For High temperature use the Pig tail assembly.
For Over pressure & vibration , use the glycerin filled gauges .
If possible extend the impulse lines and transmit the location of the Gauges from the process area to avoid the process vibration,pulsation and easy accessibility.
Regards,
symon
RE: Mean time To fail in Pressure Gauges?
They typically come with a little sticker that instructs you to, after installation, remove or pierce the little rubber plug that keeps the glycerin from running out during shipment.
An amazing proportion of experienced mechanics, and a larger proportion of engineers, claim to have never noticed the label when their failure to vent the gage is mentioned.
That conversation usually follows their reportage of improbably low pressures, often invalidating several hours of work.
Mike Halloran
Pembroke Pines, FL, USA