Emerson Exchange 365

Hello! The antenna is there for a good reason and that is to convey and to focus the microwaves in a controlled manner. Without the antenna, the pipe will in this particular case act as one, but with very unpredictable result. It is rather similar to when you have a bare bulb without reflector in your flashlight. One reason why the radar have worked for a while might be that the assembly was clean in the beginning and that you now have an extent of build-up and/or condensation that is causing disturbances in the assembly. If then the threshold settings are too narrow set, the radar will most certainly give a bad signal. When it come to the antenna, the rod antenna will not fit the 5402 as it is designed for a much lower frequency, further a rod antenna is a very bad fit in a pipe or a tall nozzle, so it would not help to use a lower frequency radar here either. My best antenna recommendation is to cut an ordinary cone antenna to fit into the pipe, with a minimum gap between the antenna opening and the pipe wall. If you cut the antenna manually; please make sure to make a clear and precise cut.
However, the above is based on the assumption that the erratic bahaviour is caused by a combination of a missing antenna, too narrow threshold settings and contamination. Only when we have more details from the actual gauge, we will know for certain - and such details would be plots from the unit, where we can see the echo curve, a backup of the database and also a visual inspection of the unit. I thus highly recommend you to contact your local Emerson service engineer to get assistance with interpreting the data from the unit and thus find out a suitable solution.

Thanks Ingemar.

What if we get a new 5401 flange-type rod antenna LT and cut our nozzle to about 100mm height? Is this the best solution? Tank height is 1500mm, excluding the 100mm nozzle.

In reply to Rein:

Hello Rein,
I believe that you can use the existing radar with a cut-to-fit cone antenna as your primary solution. Still, we need to see tank plots from the device in order to give you our best recommendations. In general, the 5402 should work fine on the nozzle, given that it is clear cut and free from obstacle - also this we can see in the tank plots from the device. We do not recommend you to use the rod antenna here. Are you familiar with how to save tank plots from the device? If not; please let us know so we can provide you with instructions. Please also let us know if you already are in contact with an Emerson service engineer, or want us to connect you to the service organization in your world area? In such case; where are you located?
Best regards,
Ingemar

In reply to Ingemar Serneby:

Thanks again, Ingemar.

But if that cut-to-fit cone antenna did not work, which among the 4 options below do you think is the best solution?

OPTION 1: Increase the hole size on the mounting flange so that the extended cone antenna can enter.

OPTION 2: Cut-to-fit the cone antenna.

OPTION 3: Use 5401 rod-type antenna and cut the nozzle height to 100mm.

OPTION 4: Use the cut-to-fit antenna of 5402 and cut the nozzle height to 100mm.

Or any other suggestions/options?

In reply to Rein:

Hello!
If possible, I would propose to cut the nozzle and use a cone antenna that is cut to fit (option 4) as my first priority. If it is not possible to cut the nozzle, I would propose an extended cone antenna (option 1). Such extended cone antenna need in such case to be ordered from factory as a "special". The third best solution is the easiest; to install a cut to fit cone antenna in the existing nozzle (option 2). This will likely work fine if the nozzle is clean, without obstructions - and it will be relatively easy to make a trial with this solution.
So: From a technical viewpont, the best solution is option 4, followed by option 1 and then by option 2.
From practical reasons I would however recommend you to first try option 2 before you go ahead and cut the nozzle as this very well might be a working solution. The fact that the unit has been in operation for a longer period of time without any antenna at all, implies that option 2 very well will work fine.
Still: It would be really good to see some tank plots from the unit to rule out the possiblility that something is wrong with the unit itself.
Best regards,
Ingemar

In reply to Ingemar Serneby:

Thanks, Ingemar. We'll do as you have said and let you know the result.

Hello again Ingemar,

We have contacted and sent request for quotation to the supplier (an LBP) of this Rosemount 5402 and they responded by saying that they will look for it. But it's been almost a week now and still no feedback in spite of repeated follow-ups. It looks like they are not interested at all. Do you know of other company who would like to supply this 2 inch cone antenna? Thanks.

In reply to Rein:

Hello Rein,
I am sorry to hear that you have still not got any reply from the supplier. I assume that you indend to purchase an extended cone antenna with taylor-made diameter, correct? I would in such case recommend you to contact your local Emerson office or local Emerson representative and they will work together with factory and/or world area on a solution.
As mentioned earlier, the easiest solution - and a solution that likely will work well - will be to cut the antenna that came together with the radar to fit into the existing nozzle (your "option 2"). This can in such case be made locally. In such case; just ensure that you make a very precise and clear cut in order to get the best conditions for the microwaves to propagate. This is likely the fastest way to reach results - and if that doesn't work well enough, you will always have the option to order a replacement antenna (extended and with taylored diameter).
Are you familiar with the RadarMaster setup software that was delievered together with the instrument? If you are; it would be very helpful if you could make copies of the tank graph (plot) and send it for our review - as we will instantly see whether the suggested method will work or not - and also to determine that the unit is sound.
Kind regards,
Ingemar

In reply to Ingemar Serneby:

Hello Ingemar,
Thanks for your response.
The local rep of Emerson in our area is not responding despite our repeated follow-ups.
I am requesting for the 2-in. cone antenna. Once we have it, we will cut it so that it can pass thru the center hole of the flange.
Yes, I know how to use the RRM tool. Unfortunately, we don't have a Fieldbus modem. Our transmitter has only the 2 terminals loop-powered FF comm. I can use the 475 Field Communicator to check the parameters. I can send you the snapshots of some of the parameters, if that is ok with you. But that will be when I get back to site and when the cone antenna is already installed.

In reply to Rein:

Hello Rein,
Where are you/the site located? I believe that we need to escalate to the world area office in order for them to assist with a new antenna. Out of curiosity; what happended with the antenna that was delivered together with the radar?
Yes, some snapshots of plots and parameters from the 475 is definitely better than nothing, so please arrange for possible snapshots when you are back on site.
Kind regards,
Ingemar

In reply to Ingemar Serneby:

The installer removed the 2 inch cone antenna from the radar after he found out that it cannot enter the flange 40mm hole. Then, somehow, they lost it as they could not find it now. So, we end up in ordering another 2 inch cone antenna. The LBP has replied and the price is US$3,000+ each. Below are the snapshots of the tank geometry configured in the device using 475 FC.

The tank height is not correct. It should be 1500mm.

The L1 & L2 are also not correct. They should be less than 20m.

Looks like I need to change some of the parameters first and test it again.

In reply to Rein:

Hello Rein,
Good to know that you now are working together with the LBP on a solution! Also good that you have found a couple of errors that you will correct during your site visit. I am however a bit concerned about the "0 mV" signal strength as I expected it to be higher - but that might be due to the configuration - however, it would have been extremely good to see some plots/echo curves from the unit in order to verify that it is sound.
Kind regards,
Ingemar

In reply to Ingemar Serneby:

But do you think wrong configuration would lead to BAD output signal/level status/signal strength?
Also, I saw that the configured pipe inner diameter is 100mm, although, it is actually only 45-50mm (DN50 + Sch.160) nozzle.
And the upper null zone is 800mm. It should not be affected by any build-up in the nozzle also.
Btw, the tank height = 1500mm horizontal tank height + 530mm nozzle height = 2030mm.
But how come it was working before with the current configuration?

In reply to Rein:

Hello Rein,
Erratic configuration may very well lead to non-working units, but you are perfectly right that this unit have been in operation, so the error will likely ”just” cause measurement deviations. I am more concerned about the threshold settings in this case as I had expected at least some signal strength. Nevertheless it is good that you will straight out the settings during your site visit. What should be really useful is some screen shots on the echo curves / plots - in order to verify that the unit itself is in good condition and that the thresholds are in good positions - preferably when the antenna is installed.
Kind regards,
Ingemar

In reply to Ingemar Serneby:

Another thing I observed in the configuration is the discrepancy in level (0-100% = 0-100mm) and the output scale (4-20mA=0-1500mm).

I'll correct it when I get to site and see if it will fix the "no output signal status". But then again, It is strange that "no output" is caused by wrong range setting.