6 replies to this topic

[Andree]

Hello,

I would like to ask if you could advise manufacturer for following item (non-standard):
a cylindrical glass vessel for operation at elevated pressure (5 barg) flanged on both ends, size: diameter 8", length 20" (to replace identical element made of standard 8" steel pipe).
This element will work as the interface level gauge in my lab-scale test rig.
I does not have to be glass, it can be made of other transparent media compatible with diesel and water.
However, I wonder if it make sense to manufacture this as whole glass element or maybe it would be easier and cheaper to fit a sight glass in the steel element...?

My issue is non-typical as I design non-standard equipment just for testing, sorry if you find it confusing.

Please share your ideas, I will appreciate all answers.

Regards,
A.

[Art Montemayor]

Andree:

Back in 1960, I earned extra money at university by working for the Texas A&M Cottonseed Laboratory. I was encharged with rigging up a test setup to absorb oil from cottonseeds. I was to try using hexane at 300 psig and I was to allow for a liquid interface.

My prof gave me a 1" Jerguson level gauge with which to do the basic setup - and it worked. Today, manufacturers like Jerguson and Penberthy have increased the size of their gauges. You may be able to find a 1.5" or 2" model. I doubt you'll find an 8" model.

If you are unfamiliar with the "armored" type of level gauge I'm referring to, then go to:

http://www.nciweb.net/prod01.htm

These type of armored level gauges can easily take 3,000 psig. If the level gauge sizes are too small, you can use a pressure vessel with a weld pad gauge mounted directly on the cylindrical wall of the vessel. I doubt if you will find an 8" diameter glass cylinder to take any reasonable degree of pressure, such as 5.0 barG.

[Andree]

Art,

This is what I have been affraid and you confirmed my anxiety, i.e. vessel diameter can be too big to make it of glass for operation at 5barg (or the glass wall should be inreasonably thick). I discussed this with my colleague working as FEA design engineer of pressure vessels, who said similar things as you wrote. Probably a weld pad gauge mounted on the wall is the best idea, however I have to consider cost and compare this with 1" level gauge connected to the steel vessel.
I was thinking about glass vessel rather than this more typical setup, because the response time of interface level indicated in the small external gauge can be retarded. It matters when level change of interface is very rapid (this is what I expect in my experiments). Moreover, when the interface is not well defined (dispersion band exists), ability of good observation is very important for process control. But I will probably have to change my concept...

Thank you for advise.

Regards,
Andrzej

[Art Montemayor]

Andree:

It's good that you responded quickly. I'm on my way home for the weekend and I thought I'd better share some past experience with you so that you can benefit from old Lessons Learned.

I totally agree with you. One of the hazards involved in trying to control a liquid-to-liquid interphase involves being able to discern the two different liquids. Sometimes this is easy; but often it becomes a nightmare and a possible hazard if you lose sight of the interphase and it goes out of the range of the visual level detector. Do not allow this to happen to you. There is a trick to amplify the ability to detect the liquid interphase: You use custom, built-in lighted plastic covers for the gage glass. All the major level gage detection manufacturers know this and even mention it. However, they don't try to explain how it works and why to readers. They simply assume that you know all about it and they will build it into your level gage if you specifically specify this additional equipment. But if you don't ask, you'll never be told or know about it --- until it is too late.

I would not install a sight level gage for the application you are talking about without built in light capabilities. It really makes a big difference - especially when your liquids tend to dirty up your level glass and it becomes even harder to detect the normal level. The extra cost is not much, compared to the grief of finding out that you can't visually detect or identify the interphase location once the system is operating.

I know that Jerguson, Jacoby Tarbox, and Penberthy all have this feature and can furnish it if it is requested.

I thought you would be interested in knowing, in case you haven't heard about it.

[mishra.anand72@gmail.com]

After due consideration, I regret to inform you to go through B2B Yellow Pages.

[Art Montemayor]

Mishra....:

Could you kindly explain who you are directing your comment to and what is it that you mean by it?

I don't understand what it is that provokes your consideration and why you have regrets about it. Also, what is meant by "B2B Yellow Pages"?

Thank you.

After due consideration, I regret to inform you to go through B2B Yellow Pages.

[Andree]

As mentioned before in this thread I decided to use a weld pad gauge mounted on the cylindrical wall for control of interface level (in sump), but I also consider mounting a sight glass on the main body of the vessel for observation. Does anybody have experience how to estimate glass thickness and maximum allowable dimensions? My pressure is not very high, 5 barg (design 7 barg), vessel will be (hopefully) SS 304L.

Btw. If somebody would be interested: I received the quotation from one English manufacturer, company name LEL, dealing with glass blowing, and they wrote:
"We can offer the following flanged glass tubes:
- 200mm OD x 7mm Wall - This will take up to approx 4.8 bar (MAX)
- 200mm OD x 9mm Wall - This will take up to approx 6.2 bar (MAX)
Connection: 20mm flat flange".