超聲波液位計近年來隨處可見,別說安裝簡便,性價比高,但如果對超聲波液位計使用不當,還是會造成不良影響的
1.蒸汽、霧氣對超聲波液位計影響: 當工作環境溫度很高時,液體介質容易產生蒸汽或霧氣,由于蒸汽比空氣要輕,所以上浮到罐頂部,形成了一層對超聲波脈沖有吸收和散射作用的蒸汽層。通過加裝靜管,可以減少或削弱蒸汽層對測量的影響。
2.泡沫對超聲波液位計影響: 在用超聲波液位計來測量液位的過程中,經常會遇到泡沫的干擾。泡沫按照屬性可以分為:干、濕、中性、重型四種。 干泡沫和濕泡沫能將超聲波反射回來,故用超聲波液位計來測量無影響;中性泡沫則會吸收和擴散部分超聲波,因而會減弱超聲波的反射,導致回波不穩定。因此當介質表面為稠而厚的泡沫時,超聲波液位計的測量誤差會較大,甚至無法測量。 在干擾嚴重的工況下,超聲波液位計可以通過加裝靜管的辦法來屏蔽泡沫的干擾。
3.攪拌對超聲波液位計影響: 現場容器常常有攪拌,液體波動比較大,影響超聲波液位計的測量;該種情況下可以適當降低攪拌器的轉速、或將探頭偏離攪拌中心;還可以安裝靜管,從而有效消除因攪拌器攪拌對液位測量產生的影響濕度傳感器探頭,不銹鋼電熱管,PT100傳感器,流體電磁閥,鑄鋁加熱器,加熱圈。
4.盲區對超聲波液位計影響: 超聲波液位計的盲區,就如同人的眼睛一樣,盲區是當物體離眼睛非常近的時候,反而看不清楚,這一段距離叫作盲區。超聲波液位計的盲區,根據量程的不同而不同。量程小,則盲區小,量程大,則盲區大。所以要求測量的液位不得高于超聲波液位計的盲區。
5.壓力和溫度對超聲波液位計影響: 首先,聲速在真空下無法傳播,而超聲波的本質是一種聲波,且屬于機械波,故它也不能在真空中傳播。 其次,是溫度,雖然超聲波液位計的參數匯總有壓力值,但是隨著溫度的升高,該壓力值會相應減小,所以在選型的時候要注意此參數。
Ultrasonic level meter can be seen everywhere in recent years, not to mention simple installation, cost-effective, but if the improper use of ultrasonic level meter, or will cause adverse effects
1. Steam, fog impact on ultrasonic level meter: when the working environment temperature is very high, the liquid medium is easy to produce steam or fog, because steam is lighter than air, so float to the top of the tank, forming a layer of ultrasonic pulse absorption and scattering of steam layer. The effect of vapor layer on measurement can be reduced or weakened by installing static pipe.
2. Foam influence on ultrasonic level meter: In the process of measuring liquid level with ultrasonic level meter, foam interference is often encountered. Foam can be divided into four types according to its properties: dry, wet, neutral and heavy. Dry foam and wet foam can reflect ultrasonic back, so there is no influence to measure with ultrasonic level gauge; Neutral foam absorbs and diffuses part of the ultrasonic wave, thus weakening the reflection of the ultrasonic wave, resulting in an unstable echo. Therefore, when the surface of the medium is thick and thick foam, the measurement error of the ultrasonic level meter will be larger, or even can not be measured. Under the condition of serious interference, ultrasonic level meter can be installed static pipe to shield the interference of foam.
3. Stirring effect on ultrasonic level meter: there is often stirring in the field container, liquid fluctuation is relatively large, affecting the measurement of ultrasonic level meter; In this case, the speed of agitator can be appropriately reduced or the probe can be deviated from the stirring center; Also can be installed static tube, so as to effectively eliminate the impact of agitator stirring on the level measurement humidity sensor probe, stainless steel electric heat pipe,PT100 sensor, fluid solenoid valve, cast aluminum heater, heating ring.
4. Blind area on ultrasonic level meter: the blind area of ultrasonic level meter, just like people's eyes, blind area is when the object is very close to the eye, but can not see clearly, this distance is called the blind area. The blind area of ultrasonic level meter is different according to the range. When the range is small, the blind area is small; when the range is large, the blind area is large. Therefore, the highest level required to be measured shall not be higher than the blind area of ultrasonic level meter.
5 pressure and temperature on the impact of ultrasonic level gauge: first of all, the speed of sound in vacuum can not spread, and the essence of ultrasonic is a kind of sound wave, and belongs to the mechanical wave, so it can not spread in vacuum. Second, is the temperature, although the ultrasonic level meter parameters summary has the maximum pressure value, but with the temperature rise, the maximum pressure value will decrease accordingly, so in the selection of the parameter should pay attention to.
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