Hello,
We have some doubts, and would appreciate if you can share or give some feedback on the term used for vibration monitoring.

How do you normally describe the vibration point locations?
Is it using NDE/DE or Inboard/Outboard or other terms(maybe Rear and Front)?
And for Centerhung and Overhung pump, is the 'Inboard' side refer to different location? Or is it always referring to the point close to coupling side/DE?

If using the DE and NDE for point location, for overhung pump, are the two bearings also called DE and NDE or just DE (maybe DE inboard and DE outboard)?

Thanks so much.

From what I am practicing over here, DE = Inboard and NDE = Outboard. Even for overhung pumps, DE/Inboard refers to the bearing location nearest to the coupling and NDE likewise.

wookp,

The literal equivalent of DE is "drive end" and NDE is "non-drive end" so these are self-explanatory.

Some people use a system like 1YD, 1XD, 2YD, 2XD for proximity probes. 1YD refers to bearing #1 looking from the driver to the driven machine. The 2nd designator refers to the "Y" transducer and the 3rd designator refers to the transducer being a proximity probe (D=displacement). With this system, if you had a turbine driving a compressor through a step-up gearbox a vertical accelerometer located on the low speed shaft, which might be bearing 3, would perhaps have a designator of 3YA. That same shaft, if it had orthogonal proximity probes, would likely have transducers designated as 3YD and 3XD. While on the topic of gearboxes the extension end of rotors are often called just that, "low speed extension" or "high speed extension" and sometimes "gear extension" or "pinion extension". The uncoupled ends, which usually don't even protrude from the housing, are often termed "blind". Thus if you talk about the "low speed blind" I know exactly what you are referring to.

What I generally don't like are conventions that refer to transducer locations using terms like north, south, east, west. If you tell me that bearing 2 north is high and bearing 2 south is low then the first thing I need to do is tell you I've never been to your plant and don't know north from south as it refers to your machine. I have to seek additional information.

Whatever system you put together should be intuitive in its use so that the user or outsider has to ask a minimal number of questions. If I walk up to a rack that has a channel identified as 39VS-91, that doesn't tell me much. If however the rack is identified as "Generator DE X" I am informed.

John from PA

Some people prefer De/Nde,some people prefer Inboard/Outboard others 01/02 etc.
Twin shafts or center hung applications maybe described as East/West North/South

Attached is one way I describe the locations, However I try to make sure that the person receiving the report understands the terminology.

DESCRIPTION.doc (203 Kb, 34 downloads)

All,
Thanks all for the input.

The reason I ask, recently I get some difference opinion from people around me that such as for Overhung type, in Pump Handbook it uses Inboard to refer the bearing close to impeller side and Outboard for close to coupling

And also for overhung type, there is no NDE bearing, both are referred as DE Inboard and DE outboard.
I've actually never heard those before, just want to know if there are more with such opinion?

As for me, DE is always the exposed moving part of the shaft (normally connected to coupling). This is normally the only part you can turn, to drive a machine regardless it is pump, motor, compressor, etc, and that is why we call it Driving End

quote:

Originally posted by John from PA:

Whatever system you put together should be intuitive in its use so that the user or outsider has to ask a minimal number of questions. If I walk up to a rack that has a channel identified as 39VS-91, that doesn't tell me much. If however the rack is identified as "Generator DE X" I am informed.

John from PA

I really do agree with you on this point.

Hi Arief,
Normally DE & NDE is used for driver equipment (e.g. motor). For driven equipment (e.g. fan and pump) is difficult to used the DE & NDE term. Much easier to use inboard and outboard for this equipment. Important is to be constant in your term.
They just giving you a hard time down there. Hehehe

Take care
Adam

John for PA,
Loved your point about 2YD and 2XD. I was on site at Chevron in Texas and was asked to confirm vibration readings on a motor that their vibration technician had taken. His terminology was not even close to your bad example. I asked everyone on site what they referred to and no one knew. Best yet, the technician was on vacation!!
Took the readings with my own nomenclature and gave them to the customer with a piece of paper describing where they were.
I have always used DE and NDE.
BEWARE!!! Do not ever use Front and Back, especially with electric motors. The boys in my field (Reliance Electric), if you order a front bearing bracket will send you the bracket that goes to the Non Drive End of the motor. The have always (1894) referred to the NDE of the motor as front and the DE (shaft end) as back.

Actually Adam we have the same problem here as Arief. The pump manufacturers refered to the outboard bearing on a overhung hung pump as being the closest to the coupling. The bearing closest to the coupling on a center hung pump is the one they refer to as the inboard.

We have one department that demands it stays that way. How did we get around it? We started using DE and NDE.

We figured there were better battles to be fought.

Aubrey

I've used the same icon-nomenclature for over 30 years. Universal to alignment & vibration. Machine orientation is standing on the outboard of the driver looking over the driver to the driven machine bearings are in the order they are encountered; A, B, C, D, E, F, etc.. Then left is left. H, V & A means horizontal, vertical and axial. Rotation CW & CCW is also viewed from the O/B of the driver. And, there are machines with split cases.
A Motor (CW) B - C Pump D (pump is split case)

CH = Pump I/B on the right side below the split.
BH = Motor I/B or coupling end or DE on right side.

Vertical pump: B1 = Mtr DE or second bearing from top in-line w/flow. B2 is transverse to flow.

Plus I use photos that are labeled and sometimes also add drawings.

It's simple directions to a location that can be easily identified by anyone. So, regardless of the system or lack thereof anyone can quickly identify a point with no guesswork.

Sam - It's good to have conventions (and I like yours), but there is always an exception. How do you handle a motor with two shafts?

We have some small dual-shaft motors driving lube oil recirculation pumps. Our solution on these is to describe the motor positions relative to the pump (i.e. MTR-CP-HORZ - Motor Circ Pump Horz and MTR-TP-HORZ - Motor Turbo Charger Pump Horz).

We also have motor generator sets with a flywheel.

GENERATOR =||= MOTOR =||= FLYWHEEL

Once again, you have a problem if you start your naming convention at the driver in this case.

Ron,

Thanks for the tip about Reliance motors. I don't make a habit of it, but I have used front and back end, although I always include a diagram on my reports.

I'll put that, along with your tips about using log scale and proper grounding, into my "file" and you can now retire knowing that your legacy will live on.

Sam, like Steve, I have exceptions for you to comment on. Two transducers, looking from driver to driven, one at 9 o'clock and one at 6 o'clock. Which is horizontal and which is vertical?

Or two probes, 135 deg left and right of top dead center?

John from PA

Steve,

So far all my 2 shaft mtrs are simple:

D Pmp 1 C -- B mtr A -- X Pmp 2 Y and again photos.

John,

9 (is that AM or PM? ) is Horz and bottom is Vertical as I do them and have them.

Regarding the eddy current probes - direction of rotation is everything. Bill recently published an orientation and which is horz and which is vert in a post of some months back as I recall as did another one of our peers. Unfortunately I'm not walking around with that in kidney matter at the moment. Hopefully Bill will jump in on this one.

Typically they are installed in the cap instead of the housing assuming I have a good mental picture - we all know I'm mental.

For what it's worth. In a past life, I used a number first and followed by a letter. The convention was increasing numeral from Driver to Driven as you hop from bearing to bearing.

1A = motor free end, axial; 2R = motor coupling end, radial; then 3A 3R 3T & 4A 4R 4T (for example)on the pump or fan or what ever is driven. So on a gearcase you increment from both ends of a pinion to both ends of intermediate shaft and output shaft. I though it was kind of easier to think of bearing number as you work through the machine.

Example case readings set up for 200 HP motor and overhung pump:

MOV = Motor outboard Vertical
MOH = Motor outboard Horizontal
MIV = Motor Inboard Vertical
MIH = Motor Inboard Horizontal
MIA = Motor Inboard Axial
PV = Pump Vertical
PH = Pump Horizontal

Pump only requires one vertical and horizontal point since bearings are ~ 12" apart and housing transmitts vibration well for trending.

For shaft probes: bearing 1 is the outermost bearing on the driver, Standing at the back of the driver work your way down the train using Y on the left, X on the right.

1Y = bearings 1 Vertical
1X = Bearing 1 horizontal
2Y = bearings 2 Vertical
2X = Bearing 2 horizontal
etc

I use what Gary "used to use", which is a numbering scheme with letter signifying direction. Starting on outboard of motor (even in case of dowuble shaft motor) the opposite drive end, or outboard is #1. Drive end, or inboard is #2. Keep numbering sequentially to the last bearing. Gearboxes are numbered by shaft (pinion drive side is #3, opposite drive side is #4). Works well when I talk to other vibe people, as when we talk #3 bearing everyone knows where that is at. I include pictures or drawings with my reports also, don't want any miscommunication about where problem lies.

Dave

Also note on mine; the distinction of Horz vs Vertical equipment.

AH, AV, BH, BV, BA vs. A1, A2, B1, B2, BA
1 = inline, 2 = Transverse to flow

Hi guys,

Interesting discussion.. We are using DE/NDE notations for every piece of equipments we have.. But sometimes it is confusing, at least for an outside guy, to find the location in some gearboxes, especially when the gearboxes have more than one intermediate shafts!! Is there any good method for denoting all the bearing locations of a gearbox?

Have a nice day!!

Jenish,

The numbering system doesn't care how many shafts you have, the odd numbers are always on the driver side and even numbers are always on the side opposite the driver. They are numbered sequentially starting with the input pinion and working your way to the output. Pretty simple.

I use DS and ODS at one place (thats what they want, I don't think any of them can count ) which denotes Driver side and Opposite Driver side. I like the numbers best though.

Dave