Reverse Mounting Arrangement For Proximity Probe

1. Do you suppose that the mounting scheme may depend on the application of the probe? Is it for bearings?

2. Is this a school project or a job?

3. If this is a real application, what does your instrument supplier have to say?

1. yes it is for bearings.

2. Its a Job ..(Power Plant BFP as i mentioned earlier)

3. Well most of local instrument dealers are not very sure. they have both is there reply!!!!

What i want to know is there any criteria for selection of mounting arrangement of Proximity probe?

and what benefit (if is) reverse mounting provide over direct mounting?

SHyam

www.ballus.com says:

Flush Mounting: The "active surface" of the sensor may be set flush with the metal surface in which the switch is mounted. However, the "active surface" must have a free zone in which no metal is present.

Opposite Mounting: When mounting proximity sensor "active surfaces" opposite from one another, there must be a minimum distance of 6 x Sensing Distance between them. This is to prevent the electric fields from "cross talking" and false tripping the sensors.

It is good engineering practice to mount proximity sensors either horizontally or vertically with the active surface facing down. Whenever possible, avoid mounting proximity switches either face up or at an angle that could "trap" contaminants, especially if metal filings, chips, water, coolant, or other debris are present. This is to prevent a chip or other debris from landing on the face of the switch and "sticking" the switch in the "ON" position.

This is not my field. Come to think of it, I don't have a field anymore.

Skasnl,

I was checking the API 670 fourth edition and I dont see anything talking about direct o reverse mounting.

Please, Can you show us some document or image regarding those mounting options?

Regards
JP

@JP,

It is mentioned in API 670. I am not having access to API 670 right now, otherwise i wd have mentioned the page no. Please see the attached datasheet below:

Skasnl

I was checking deeply your question and I suppose you are talking about Benlty Nevada probe's or not?, therefore, I am associating the reverse mounting option with this systems.

According to Bently Nevada the reverse mounting probes are used exclusively with the 31000 and 32000 housings, these have its reason, the probe is threaded inside the housing tubing (this is called probe sleeve), contact to local bently nevada support in order to know more about this housings.

Direct mount probes are using if you are going to install the probes directly over the bearing housing or something like that.

These two option mounting have its advantages, Request more information to Benlty Nevada.

I will be putting some images in order to help

I hope this help

Regards

JP

Thank you JP....

You are correct that these probes are mounted with housing. And this kind of arrangement is available with almost all VMS suppliers. I tried to talk to local supplier they have all information abt both type of arrangement....But they are not very sure abt reason...why and when one should go for Reverse mounting probe?

I will try to talk to some more vendors.....and will post if get to know something new

Thank you all for your replies !! :)

Regards,

Shyam

This depends on the physical arrangement of available or easy-to-make brackets for mounting the sensor, and which way the sensor needs to point. Drawings or sketches would help.

Hy Skasnl

The difference between direct and reverse mounting, from your diagram, seems to be the distance from the locking nut to the sensing face. If your surface to be sensed is close to the surface where the lock nut is then reverse would be your choice. It the surface to be sensed is down a hole then direct mounting might be your best choice. It all depends on the physical dimensions of your application.

Most of our proxies are threaded over the entire sensor body length so we don't have this issue.

The question I have, is why would you want to put a proximity sensor on a bearing? I could understand putting a temperature or vibration sensor there but not a proximity sensor.

Hi Elory,

Well..May be you are correct....but i want to understand in bit more detail..

any way about yr question:

Actually i have to put two proximity probes on Pump bearing in X-Y direction (90 degree apart) for measuring shaft absolute vibration. While preparing specification i found all these confusing things.

Thanks,

Shyam

There are companies out there that make vibration sensors.

This is a VKV021 From IFM Effector. I'm sure there are other companies as well. I've never used one of these so I can't speak as to how well it works.

Elroy

Hi, I think prox. probes are use on babbitt bearings at 90 degrees apart to look for oil whip problems on start up and bearing wear. This is also used on the larger rotating units or high speed centrifugals for run out and Vibe.

I'd be very careful with ifm products made of plastic, I had major reliability issues with several proximity switch series and finally had to preventively replace all the originally installed ones by better products. Not bashing a manufacturer, just based on many years of experience in the industry.