Fuel going thru Air Eliminators 2

[caluna]

Fuel leaking thru Air Eliminators at tank farm dispenser bldgs.
In several of our installations we have had problems with fuel leaking thru air eliminators. These are small scale dispensing facilities for diesel. We do not have this propblem in every facility, nor can we figure out why it occurs in some and not in others. We have Neptune compact meters with air eliminators located in the piping. We have looked at the PRVs in bypasses around all the valves on the lines and checked them for direction of flow and setting. Even when these are all OK we are still having troubles in one location with fuel blowing thru. Any thoughts?
thanks.

 

[jmw]

I do hope you can manage to contact Neptune, or whoever they are today.
The fact is they have experienced crushed floats previously and they did develop and produce a "crush-proof" foam filled float.
This suggests the problem has a relatively common cause (and possibly related to hammer or large amounts of entrained air - liquid following through after air can have a significant shock effect and is one of the major causes of damage to PD meters) and one that required a product design solution rather than an operational solution, at least, in many cases.

The point being that many installations and operations are not ideal but are reasonable and that if normal conditions creates situations where the standard float is vulnerable then the crush-proof float is a solution i.e. survivability was considered more practicable than remedial action to prevent what is probably an occasional transient condition (the floats don't crush on a daily basis).

However, from your investigations so far, there is a possibility that the cause is not an acceptable transient condition; you have reported that some PRVs were installed wrongly and this may indicate other problems that can and should be remedied.

I would hope that Neptune can give some greater insights based on their experience. Or, you could try one of the other manufacturers for their experience (they'd love the opportunity to be able to supply alternative equipment if they can show it is an equipment design fault and they'd need to be sure their own equipment doesn't suffer a similar fate). You might try some of the other manufacturers for their advice e.g. such as Liquid Controls, Smiths etc.



JMW

http://www.ViscoAnalyser.com

 

[kenneth2]

Thank you so much JMW for this. We are looking into the solid composite balls however it seems to be a quick fix not addressing the root cause. We are all at a loss to understand where such a large liquid hammer effect could be coming from. Possible the slamming of the preset auto stop valve bolted to the meter itself just downstream of the air eliminator ( with the ball inside ). If a pressure spike as large as 500 psig was occurring I would venture to say that more than just a ball float would be failing as these devices ( Actaris type 4 MT petroleum meter 2 inch) would show other signs of failures at these pressures. Not so -we have not seen anything other than clearly imploded/folded floats. Actaris/Neptune ( now Itron out of Greenwood South carolina 1-800-833-3357_) are involved. THeye emaintain that these stainless steel ball floats are used in both LPG and pertoeluam fuel applicataions and are all tested to 500psig.

 

[BigInch]

It would be interesting to see if a fast application of -40 temp on one side and a relatively warm temp on the other side would fold it in.

I've always been told that you have to maintain a backpressure on meters, holding them full of liquid when they are shut down, so you don't get the slugging into air filled lines and impacts on the turbines when you restart flow. If they were down for servicing, and drained, we fill them manually, venting all air out before restarting flow. As I have always designed, operated and worked with metering systems that did have about a 25 psig minimum backpressure held against them, I can't really say if not having that backpressure could be responsible.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[jmw]

kenneth2,
what do they say about the foam filled float?

Incidentally, I see something new to me on their website which is a differential valve installed downstream of the meter and connected to the air release;

http://www.neptuneflowmeter.com/literature/M-663(B).pdf

This is for use where there is more air than the air release can handle and which would therefore flow through the meter if flow were to continue.
I'm just trying to figure out if, where there is a situation of crushing floats, this would help or amplify the problem.

In the O&M Manual I find this:
[quote[Air Release Valve Troubles
Troubles with this unit may arise from:
a) Collapsed ball float allowing vent to remain open.[/quote]

http://www.neptuneflowmeter.com/literature/M-203(A).pdf

In other words, this happens and hopefully they should be able to diagnose the common causes.


JMW

http://www.ViscoAnalyser.com

 

[kenneth2]

Thank you JMW.. I have seen the literature you have mentioned and have read about this differential device. What I am proposing to the GNWT is that I attend the site wih the operations supervisor and do a thorough system check.. In ther words, we would install a pressure gauge on the drain plug port on the type 4 Mt petroleum meter. We would re-establish the vent ( it was plugged on Dec 19/08 after these ball failures were allowing fuel to spill everywhere in the building thru the vent) and start the pump. I would use a stethiscsope to listen while we start up, then watch the gauge and flow thru the vent while we load a bulk truck at 130 LPM. If this is a hammer situatiion I strongly suspect one could hear this immediately on start up, which wopuld be oserved as well as a large pressure spike on the gauge ( > 500psig) WE will then observe if fuel flows up vent, and shut down, take apart and inspect the ball. The solid composite balls are available according to Acatris in Greenwood but were mainly designed and used in Europe. The supplier Accuflo of these meters had not even heard of the composite solid flaots. Anyways we plod on.

 

[786392]

Nice suggestion, should provide way forward,
sorry for late comments

Best Regards
Qalander(Chem)

 

[kenneth2]

THank you all for the comments. I will keep posting what happens.