What is causing the arcing in our hydraulic flowmeter?

In summary: But in general, it sounds like the build-up of static electricity on non-conductive surfaces can cause an arc.
  • #1
tomc5
3
0
I think my situation below can only be explained by a physicist, so I hope I came to the right place!

On our hydraulic test bench we use a glass tube, float type flowmeter (also called a rotameter?); fluid is hydraulic fluid and non-flammable; the float is anodized aluminum. We occasionally get a report of arcing in this flowmeter, but reports and descriptions of the event are non-specific except that "an arc (or spark )was seen inside the tube". I am told in one instance that the glass tube shattered.

My initial conclusion was we simply had a bad metal-to-metal contact between the flowmeter metal base and the back panel, but all surfaces were clean. We then also added a ground wire between the flowmeter metal base and an Earth ground with no apparent effect on preventing the arc.

1. what is the possible cause of this charge buildup?
2. where is the charge being stored? On the Glass? or on the anodized float?
3. what else can I do to prevent the arc?

I have called several flowmeter companies but rec'd no help in explaining the phenomenon.
Thanks for any explanations you can offer.
Tom
 
Physics news on Phys.org
  • #2
If charge is being stored it will be on the glass tube, so grounding the frame will not help.

Is your hydraulic fluid conductive? If so I do not see how a charge will develop. However, if it is non conductive then the possibly of a charge build up approaches certainty. One way to prevent this may be to insert a grounded metallic section in the flow path just before the glass tube. If that does not work perhaps (This is just a thought on my part ) perhaps you could connect the metallic section of tube to a "de Ionizer" this would consist of a low voltage AC signal applied to the tube. The idea would be to induce positive and negative charges which would prevent any significant build up of charge hopefully maintaining a neutral charge on all non conductive surfaces.

This is all wild speculation on my part, have you tried contacting the manufacture of the hydraulic fluid? They may have some helpful information.


EDIT:
A bit of googling shows that static build up is a relatively common issue. It appears that there are filters designed to prevent this. There are also static disapative lines available. Again, contact the manufacturer of your fluid, they should be able to help.
 
Last edited:
  • #3
Sigma-
Thanks for your quick reply.
I am certain the hydraulic fluid we are using is non-conductive although I cannot “quantify” how non-conductive it is. It is a synthetic oil (polyalphaolephin-based oil).

If charge is building up on the inside surface of the glass tube, I imagine it builds to a value which allows it to arc over to some grounded part of the flowmeter, i.e., the metal base which supports and encloses the tube. There is contact between the glass tube and the base, so why can’t the charge just drain off to the base rather than arcing?

Is it possible charge is building up on the anodized aluminum float and then arcing over to the glass as it finds ground through the metal base, or just arcing from float to base?

Thanks again,
Tom
 
  • #4
The trouble is, since the glass tube is an insulator the charges are not mobile and cannot all drain off at the base. Your best bet may be one of those de ionizing filters or static dissipative hoses.
 
  • #5
I've been web searching your idea of adding a deionizer in the form of filter as you suggested. I will also have to study how these devices will affect my flow and system pressure requirements (very hi pressure = 3500 psi and flow is 25-30 gpm). Your original idea of an active deionizer is also interesting to me.

However, I am not clear on what the theory would be in my application; would the deionizing process pretreat the fluid to some charged state before it reaches the glass tube so that flow within the glass tube gets neutralized somehow? I'm way out of my league here, so your help is greatly appreciated.

Thanks again,
Tom
 
  • #6
We have had certain hydraulic systems experience the same phenomena. However our situations involved the hydraulic lines themselves arcing and eventually splitting. I can not remember the particular hose type went to after the problems arose. I would have to look that up come Monday.
 

1. What is an arcing flowmeter phenomenon?

The arcing flowmeter phenomenon is a phenomenon that occurs in certain types of flowmeters, where an electrical discharge or spark is produced in the fluid being measured. This discharge can cause inaccuracies in the flow measurement and can also damage the flowmeter itself.

2. What causes the arcing flowmeter phenomenon?

The arcing flowmeter phenomenon is caused by the presence of electrically conductive particles or impurities in the fluid being measured. When these particles come into contact with the electrodes or other electrically conductive components in the flowmeter, it can create an electrical discharge or spark.

3. How can the arcing flowmeter phenomenon be prevented?

To prevent the arcing flowmeter phenomenon, it is important to ensure that the fluid being measured is free from electrically conductive particles or impurities. This can be achieved by properly filtering the fluid before it enters the flowmeter. Regular maintenance and cleaning of the flowmeter can also help prevent the buildup of impurities that can lead to arcing.

4. What are the consequences of the arcing flowmeter phenomenon?

The arcing flowmeter phenomenon can lead to inaccurate flow measurements, which can affect the overall efficiency and performance of a system. It can also cause damage to the flowmeter, leading to costly repairs or replacements. In some cases, the electrical discharge can even pose a safety hazard in certain environments.

5. Are there any specific types of flowmeters that are more prone to the arcing flowmeter phenomenon?

The arcing flowmeter phenomenon can occur in any flowmeter that has electrically conductive components or electrodes. However, it is more common in flowmeters that use electromagnetic or ultrasonic principles, as these types of flowmeters rely on electrical signals to measure flow. It is important to consult with a flowmeter expert to determine the best type of flowmeter for a specific application to minimize the risk of arcing.

Similar threads

  • Electromagnetism
Replies
5
Views
2K
  • Introductory Physics Homework Help
Replies
3
Views
1K
Replies
46
Views
2K
  • Mechanical Engineering
Replies
1
Views
3K
Replies
8
Views
6K
Replies
4
Views
3K
  • Quantum Physics
2
Replies
45
Views
9K
Replies
1
Views
1K
  • High Energy, Nuclear, Particle Physics
Replies
8
Views
3K
Replies
2
Views
7K
Back
Top