Looking to find alternative ways to measure LPG level in an underground LPG cavern that goes down 600 feet into the ground. Does anyone have any good contacts for this or experience with this? Currently we use a nitrogen bubbler system and a wire gage system, but the wire gage system hangs up down in the shaft pipe going down into the cavern at the 14 foot level.

 

I'm not sure I understand you. Is the measurement range 600 feet, or is the shaft to the cavern 600 feet?

In either case, I don't know of anybody who has done a successful noncontact application, either radar or laser that far. I don't think radar will work past about 100 feet. You might check with TN/KSI about the OpTech Laser system they are now selling.

Otherwise, I'd put in redundant nitrogen bubblers and go with what works.

Walt Boyes
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Walt Boyes -- MarketingPractice Consultants
[email protected]
21118 SE 278th
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253-709-5046 cell
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fax:801-749-7142
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Radar may be a possibility but more details are required on what you have and what you need for accuracy.

 

Radar is probably not an option with LPG unless you can get a guided waveguide type that will cover the distance - the dielectric constant at around 1.5-1.8 is too low.

Bruce

 

I'm not sure I understand you. Is the measurement range 600 feet, or is the shaft to the cavern 600 feet?

In either case, I don't know of anybody who has done a successful noncontact application, either radar or laser that far. I don't think radar will work past about 100 feet. You might check with TN/KSI about the OpTech Laser system they are now selling.

Otherwise, I'd put in redundant nitrogen bubblers and go with what works.

Walt Boyes
---------------------------------------------
Walt Boyes -- MarketingPractice Consultants
[email protected]
21118 SE 278th
Place - Maple Valley, WA 98038
253-709-5046 cell
425-432-8262 home office
fax:801-749-7142
---------------------------------------------

 

Can anyone on this string explain why the nitrogen bubbler is required for this application vs. just measuring differential pressure across the 2 tubes (one inserted to near the bottom of the cavern and one inserted into the vapor space at the top of the cavern) without the Nitrogen?

 

It's simple, it works, it's reliable and nearly everyone understands the operation.

 

Can anyone on this string explain why the nitrogen bubbler is required for this application vs. just measuring differential pressure across the 2 tubes (one inserted to near the bottom of the cavern and one inserted into the vapor space at the top of the cavern) without the Nitrogen?

If a gas with a higher vapor pressure is not used to purge the bubbler tubes, the LPG vapor pressure in both tubes will be the same and not have a differential pressure to measure. A gas that will be incondensable at cavern pressure and temperature should be used for two reasons: 1) to have relatively the same density in both tubes so that the head of the gas column difference is negligible for accuracy of differential pressure measurement, and 2) the purge gas sweeps accumulated LPG vapor during the purge or reduced it to negligible amounts. The goal is to measure the liquid level only. Nitrogen is relatively inexpensive for the application and inert. Methane or natural gas has been used in place of nitrogen by few cavern operators. Be careful with accumulation of these "incondensable" gasses in your cavern, raising cavern operating pressures and contamination.