【Q&A Question 051】February 20, 2017
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This post was last edited by 955559 on 2017-7-21 21:57. [Q&A Question No. 051] 2017.02.20: How to determine whether the indication of a glass level gauge is accurate? The reference answers will be visible after responding; points are awarded by identifying the key points. (Unless otherwise specified, all questions and answers are based on hydrogenation units.) ) First, close the upper and lower lead valves on the level gauge to empty it, then open the upper and lower leads separately (keeping one of them closed). If fluid flows into the glass level gauge in both cases, it indicates that the two leads are functioning properly and providing accurate readings. To confirm the glass level gauge, please visit the Petrochemical Section – “Creative Ideas for Energy Saving” event: http://bbs.hcbbs.com/thread-1666758-1-1.html. Voting for the 2016 HaiChuan Top 10 Members has started; choose the member you care most about (please cast your valuable vote for those in the Petrochemical Section): http://bbs.hcbbs.com/thread-1667649-1-1.html. Summary thread of Q&A questions for 2017 (updates available): http://bbs.hcbbs.com/thread-1657793-1-1.html. Summary thread of daily questions for 2017 (updates available): http://bbs.hcbbs.com/thread-1657794-1-1.html. Summary thread of Q&A questions from 2016 (already updated): http://bbs.hcbbs.com/thread-1597792-1-1.html. Third phase of the HaiChuan Outstanding Management Members selection contest: http://bbs.hcbbs.com/thread-1655902-1-1.html. Petrochemical Section – “Creative Ideas for Energy Saving” event: http://bbs.hcbbs.com/thread-1666758-1-1.html. Xiaomi phones are available for grabs. Thread for collecting chemical industry technical materials in the Petrochemical Section: http://bbs.hcbbs.com/thread-1654603-1-1.html. Many prizes are waiting for you (Source: HaiChuan Chemical Forum)
First, close the upper and lower lead valves on the level gauge to empty it, then open the upper and lower leads separately (keeping one of them closed). If fluid flows into the glass level gauge in both cases, it indicates that the two leads are unobstructed, and thus it can be confirmed that the glass level gauge is giving accurate readings
Answer: First, close the upper and lower lead valves of the glass level gauge to empty the gauge, then open the upper and lower lead valves separately (keeping one of the leads closed). If fluid flows into the glass level gauge in both cases, it indicates that both leads are unobstructed, and thus the accuracy of the gauge’s indication can be confirmed.
Compare the liquid level inside the tank; if possible, drain some of it to see whether the level rises back again.
As long as the glass plate level gauge is not clogged, there should be no problems. Approval can be obtained by checking the liquid level: close the root valve, then open both the root valve and the drain valve to see if any fluid flows out. If everything is smooth, the glass panel should be fine.
Flushing level gauge! Check whether the pressure tapping pipeline is blocked!
To determine the accuracy of a glass plate level gauge, simply drain the gauge and then open the upper and lower shut-off valves of the gauge to see if it can return to its original position.
The glass plate level gauge utilizes the principle of a fluid ‘U’-tube, where the liquid levels in the two tubes remain at the same level; thus, the liquid level inside the tower is identical to the level indicated by the glass plate. Incorrect readings from glass plate level gauges cause problems in the operation of distillation towers or storage tanks. The key to proper use of a glass plate level gauge is to ensure that the connections at the upper and lower ends of the glass plate to the tank are unobstructed; if either of these connections becomes blocked, it will affect the accurate indication of the level gauge. In winter, when temperatures are low, poor insulation can cause heavy oils to solidify, while light oils may become clogged with impurities such as rust; both situations can lead to malfunctioning level gauge readings and produce false indications. When using a glass plate level gauge, it should be compared with the level controlled by the instrument. If there is a discrepancy in the level indicated by the glass plate level gauge, it is necessary to check whether the heating is adequate and whether the gauge is sensitive. The level or boundary level can be increased or decreased to determine whether the indication provided by the glass plate level gauge is accurate.
To determine the accuracy of a glass plate level gauge, simply drain the gauge and then open the upper and lower shut-off valves of the gauge to see if it can return to its original position.
First, close the upper root valve and open the lower root valve, then open the lowest drain valve to check whether liquid flows out under positive pressure; if there is negative pressure, gas will be drawn in； Then try again to see if the root valve above is unobstructed.
On-site level gauges made of glass tubes or glass plates generally do not suffer from distortion. If distortion does occur, it is usually due to blockages in the upper and lower connection pipes. One can first close the upper root valve, open the lower root valve, and then open the lowest drain valve to check whether liquid flows out under positive pressure; if there is negative pressure, then gas will be drawn in； Then try again to see if the root valve above is unobstructed. If it’s fully connected, it is generally accurate.