量程比

涡街流量计因其介质适应性强、可靠性高、压力损失小、量程比宽等优点，在许多行业中得到了广泛应用。

Vortex flowmeter is widely used according to its advantages of better adaptability , higher reliability , lower pressure loss , wider range ratio and so on .

结果表明本数字涡街流量计具有很低的测量下限，有效地扩大了涡街的量程比，抗干扰能力强，实时性好，具有很高的实用价值。

The result shows that the pulse output model digital vortex flowmeter has a satisfying lower limit of measurable flow rate that increases the range ratio effectively , strong antijamming ability and good real time and thus it is of great practicability .

数字信号处理方法具有抗干扰能力强、精度高、量程比宽等优点，一般采用DSP芯片来实现。

Digital signal processing methods have many advantages , e.g. strong anti-interference ability , high precision and large turn-down ratio , and they are implemented by DSP chips commonly .

认为可以用Re（c1）的值作为判别涡轮流量计特性曲线优劣的准则数，对仪表结构参数进行优化设计，以扩大仪表的量程比。

It can be used to judge the characteristic curves of the turbine flowmeter and choose the optimum design parameters of turbine flowmeter s to increase the ratio of measurement range .

变送器的量程比与精确度

Accuracy and turndown ratio of the transmitters

但是，将其用于低流速测量时仍存在明显不足，涡街的有用信号被强噪声淹没，从而导致无法提取有用信号，致使涡街的量程比小，测不到更低的流量下限。

However , it has poor performance at low flow rate where the useful vortex signal is submerged by stronger noises and hard to be retrieved .

本文在传统射流流量计的基础上，设计了新的振荡腔结构，目的在于拓宽新型射流流量计的量程比，提高其工作的适应性和稳定性。

A fluidic flowmeter with new structure is designed in this work on the basis of the traditional ones in order to widen its measurement range .

涡街流量计易受噪声影响，现场测量精度得不到保证，量程比受限。

Vortex flowmeters are subjected to the influence of noise , so their measurement accuracy can not be ensured in industrial fields and the turn-down ratio is limited .

用现有的模拟处理方法，不能保证流量计的现场测量精度，流量计的量程比受限。

The analogy circuits in flowmeter are unable to ensure the measuring precision of flowmeters in fields , and make the span ratio of flowmeter lower than theoretical value .

然而，孔板流量计存在着一些固有的缺陷，如流出系数不稳定、线形差、重复性不高、准确度受客观因素制约而无法达到设计要求、量程比小、压损大等。

However , the orifice flow meter has some inherent deficiencies , for example instability of the outflow coefficient ; poor liner , low repeatability , big pressure drop .

目前涡街流量计所采用的放大、滤波、整形、计数的处理方式，在从噪声中提取流量信号方面存在较大的局限性，只能采用限制量程比、不测小流量等方法来抑制噪声。

The traditional signal processing methods that amplify , filter , rectify signal and count , which are used in vortex flowmeter now , has shortage in extracting real flow signal from noise .

因其具有可靠性高、压力损失小、量程比宽等优点，被广泛应用于化工、石油、冶金、轻工、食品等流程工业。

It has many advantages such as low pressure loss , wide measurement range , stabilization and so on . Therefore , it is widely used in chemical industry , petroleum , metallurgy , food industry and other flow industry .

然后对小流量时的仪表系数进行了非线性修正，改善了线性度，拓宽了量程比。

It was verified that the eddy current turbine type flow meter improved the performance at low flow rate . Then , the meter factor below the low flow limit was corrected to improve the linearity and the flow range was broadened .

涡街流量传感器是一种比较新型的速度式流量传感器，它具有可靠性高、压力损失小、量程比宽等优点，因此被广泛应用于化工、石油、冶金、轻工、食品等流程工业中。

Vortex flowmeter is a kind of novel velocity-type flowmeter with the advantages of stabilization , low pressure loss and wide measurement range , so it is widely used in chemical industry , petroleum , metallurgy , light industry , food industry and other flow industry .

低流量测量仪表存在易受噪声干扰、现场测量精度不高、量程比有限等问题，需要采用数字信号处理的方法以得到准确的流速测量结果。

Flowmeter of low velocity is subjected to noise disturb , the measuring accuracy in industrial fields is not high , the span ratio is lower than the theoretic value . It need adopts digital signal processing methods to improve flowmeter and get accurate velocity of flow measure result .

例如，欲制作量程阈值比达到105量级的传感器，所用晶振的频率稳定度必须优于108。

For example , if the ratio of the range and threshold value is 105 , the frequency stability of quartz oscillator must be better 10-8 .

此外，国外变送器的测量精度达到0.05%，量程缩放比为1：400，稳定性和寿命5年以上，通信协议更加完善，并且通过安全认证。

Furthermore , it can make the accuracy as 0.05 % , measure ratio to 1:400 and stability & longevity can remain more five years . The communication protocols of those transmitters are more perfect and acquire security certificate .

在差压计量程上限不变的条件下，量程比可达1：9，测量精度可达0.5%。

As the upper limit of the different pressure meter range is unchanged , the range ratio is up to1: 9.The measurement accuracy is up to 0.5 % .