Mass flow meter installation

Status
Not open for further replies.
R

Ron K

Member
I am for the first time working in a class 1 div 2 area. B/C/D. I have to install in a room 5 mass flow meters that themselves are rated correctly. However, they have an D shell connection where 2 of the wires in this cable are for 24vdc power supply(supplied), and am using 2 of the other wires for control by a DCS, 4-20ma. These meters have to be visual of course so bottle flow rate can be monitored. I am thinking running rigid conduit to 5 indivual boxes mounting a 120V recepticle in each to make use of the plug in power supply supplied with the unit. Would a stainless 4x box be sufficient here as long as I seal the inputs? I was thinking of mounting the MFM on individual 'shelves' and running the cable into the box mentioned. Any thoughts? Anyone do anything like this before? These measure flow by the way of N2, Ar, CO2, CO and H2. Thanks for any responses.
 
sorry

sorry

Sorry folks, my first time posting and did not know why my original post did not show, so I re-posted. Apologies, learning the ropes of the board.
 
Ron,
I am thinking running rigid conduit to 5 indivual boxes mounting a 120V recepticle in each to make use of the plug in power supply supplied with the unit. Would a stainless 4x box be sufficient here as long as I seal the inputs?
Click to expand...
Take a look at 501.105(B)(6). You can do that if you follow all of the restrictions in that section. If you can't meet those rules you will have to install explosionproof receptacles. If it is not too late it would be better to use hard wired versions of the mass flow meter.
Don
 
Also look at the mfr install instructions in the MFM manual. Most mfr will have very clear instructions on the hazardous area install, including device locations and proper grounding.

Some MFM have a flow element rated for the area, and a spearate display and transmitter that has to be located in a non-hazardous area. The plug-in power supply may be intended for install in the safe area. Verfiy in the manual.
 
Thanks for the replies folks. Appreciated. These are not Coriollis or anything, just the Sierra Mass flow type.

http://www.sierrainstruments.com/products/c100.html

Turns out things have changed anyway, there are now 7 to mount, but I will be doing so in a purged panel outside. Still class 1 div 2 but now at least have a panel to mount outside. Using a din rail mount 24 vdc power supply.
 
Mass flow meters

Mass flow meters

Hi Ron, Welcome to the forum. You'll learn more from this group of folks than any you've worked with before. Very sharp bunch.

I used to do a little work in these areas also, class 1, Div 1 I only worked with Rosemount meters. (Foxboro DCS platform) I used to get with the lead pipefitter to weld some 1/4 - 20 cap screws on each side of the meter, so I could lug a pigtail and bond each side of the process pipe to the meter as required by the Rosemount install manual. Im sure your Sierra meters will have a similar install requirment.

I remember that the box on these transmitters were already rated for C1D1 locals, with all terminals inside it. I would hard pipe everything, seals where required, first pull box would be in a different room.

Good luck

Steve
 
Interesting responses. I was under the impression that a panel in a class 1 div 2 area if not rated other than outdoor/weatherproof would be fine if a purge kit is used.

I would like to hear more, as this is going on all over our site. Purging seems to be an acceptable practice. I in fact have another panel that controls the burner mgmt. system, 4-20 ma. control, etc. It is not rated but weatherproof, but a purge kit will be installed and this was deemed acceptable by the 'powers that be'. In fact, there will be many panels such as our Delta V, all with purge kits.

To Sundowner...we have tons of Rosemount stuff(as you know now Emerson). PIT's, FIT's, DVC's, Corriollis, etc. We are using Fieldbus. The marshalling panels will be stainless 4X.

Thanks for the idea of the pigtail, am doing almost exactly what you say, and have done this in my last installation also in which parts were C1D2 and parts were not.

The pull box is in a different room.
 
Ron,

Purging is an acceptable practice. My concern for your install - It appeared from your post the flowmeters themselves were to be installed in a purged enclosure. Adding the potential flammable leak source to the inside of a purged enclosure brings in additional requirements that do not apply if the flammable source is located outside of your enclosure.

Bob
 
Ron K said:
Interesting responses. I was under the impression that a panel in a class 1 div 2 area if not rated other than outdoor/weatherproof would be fine if a purge kit is used...
Click to expand...
This is why you must become more familiar with NFPA 496.

Bob G directed you to Chapter 8; I'd like to point you toward the basic definitions of purging and pressurization in Chapter 3. There is a subtle but significant difference between them and what it appears from the OP and your follow-up response is you may actually be trying to use ?pressurization? techniques rather than ?purging? in your application.

Proper purging is even more restrictive than pressurization.
 
Thanks for all your replies. Things have gotten worse, now that 'deadline' is approaching, so many codes have been violated it is unreal.

We are however purging where applicable. (not pressurizing). Numerous purge panels have been ordered and being installed in classified areas.

With that said, startup day will be a day I take off. :)
 
Ron, the plant I worked at had these meters all over the place, all in class 1 div 2. The meter enclosures were listed explosion proof, so all that was needed was to mount on stand, run rigid conduit and pour seals at the meter (I am not sure on grounding requirements however).
 
Status
Not open for further replies.
Top