When solenoid valve is losing power (de-energized) due to shutdown or other reason, it will actuate to its normal position. On regular solenoid valve, it can be put back to operating condition by energizing the solenoid. While on solenoid valve with manual reset, it will not be so. After being energized, it should be manually resetted prior back into normal operation. So it works like a local permissive. 
The necessity of having a manual reset in solenoid valve should be determined during design phase, this shall be identified by process engineer or by operator through HAZOP. The philosophy is based on whether the operator is required to be present on site or not. He/she should check the surrounding condition and make sure everything on site is normal (e.g. no hydrocarbon spill) before resetting the valve.
Thursday, September 4, 2008
Solenoid Valve with Manual Reset
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3 comments:
Hello,
As you know, there are three kinds of construction type for solenoid valve manual reset in the market, i.e., Electrically Tripped, No Voltage Release and Free Handle. But I don't very understand what the difference is? Could you please describe that clear?
Many thanks a lot.
I think your statement is incorrect. The solenoid must be energized prior to manually resetting the solenoid via the maual reset lever. You can confirm this with either an ASCO Representative or an ASCO application engineer.
Tim, thank you for the correction. Now it has been updated.
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