I have searched and found many good posts on static discharge, but nothing which relates to my situation:
On our hydraulic test benches we use a glass tube, float type flowmeter; fluid is Mil type hydraulic and non-flammable. We occasionally get a report of arcing from this flowmeter, but reports and descriptions of the event are non-specific except that "an arc (or spark )was seen inside the tube between the float and the float stop". I am told in one instance that the glass tube shattered.
I was tempted to jump to a conclusion that we simply had a bad metal-to-metal contact between the flowmeter housing and the back panel, but all connections look clean. I have other reports which claim a ground wire was added between the flowmeter metal case and an earth ground with no apparent effect on preventing the arc. The arc cannot be duplicated upon request, and so I am at a loss to view the phenomenon myself.
1. what is the possible cause of this charge buildup?
2. how does fluid velocity effect size of the charge buildup? (Typical flow measurements are ~20gpm)
3. is it possible to strap a cable to the glass (externally)and connect it to the chassis ground, will this do any good?
4. what else can I do to prevent the arc?
Any advice or explanations of this phenomenon are welcome.
Please help and thankyou.
Tom
On our hydraulic test benches we use a glass tube, float type flowmeter; fluid is Mil type hydraulic and non-flammable. We occasionally get a report of arcing from this flowmeter, but reports and descriptions of the event are non-specific except that "an arc (or spark )was seen inside the tube between the float and the float stop". I am told in one instance that the glass tube shattered.
I was tempted to jump to a conclusion that we simply had a bad metal-to-metal contact between the flowmeter housing and the back panel, but all connections look clean. I have other reports which claim a ground wire was added between the flowmeter metal case and an earth ground with no apparent effect on preventing the arc. The arc cannot be duplicated upon request, and so I am at a loss to view the phenomenon myself.
1. what is the possible cause of this charge buildup?
2. how does fluid velocity effect size of the charge buildup? (Typical flow measurements are ~20gpm)
3. is it possible to strap a cable to the glass (externally)and connect it to the chassis ground, will this do any good?
4. what else can I do to prevent the arc?
Any advice or explanations of this phenomenon are welcome.
Please help and thankyou.
Tom