1Turbine Flowmeter features

From the front of the discussion we can see that there is a turbine flowmeter many advantages flow meters. To sum up, it has the following characteristics.

(1)High accuracy

Turbine flowmeter accuracy (0.5-0. 1) percent. Within the scope of online traffic, even if the flow changes, and the cumulative flow will not reduce the accuracy. And in a short period of time, a replay of the turbine flowmeter up to 0.05 percent.

(2)Range than the width

Turbine Flowmeter than the range up to 8-10. In the same diameter, the largest turbine flowmeter flow value is greater than many other flowmeters.

(3)Adaptable

Turbine flowmeter can be made into closed structure, its speed signal non-contact measurement, so easy to achieve high-pressure-resistant design.

If the turbine flow meter and select high temperature bearings, the coefficient of thermal expansion of the small material, it can in a wide temperature range of use. At this time, it should be noted that the instrument coefficient (mainly the flow of cross-section of the change):

KK 0 [1( R 2 H )(tto)] (323)

In-K, K 0 - when the use of the instruments and calibration coefficient;

tt 0 Use and check the fluid temperature

R H For turbines and chassis materials expansion coefficient

(4)Digital signal output

Turbine Flowmeter output and flow in direct proportion to the pulse digital signal. It is in the process of transmission does not reduce the accuracy and easy to accumulate and easy to send the advantages of the computer system.

2. Turbine flowmeter installation

To give full play to the characteristics of turbine flow meter, flow meter on the installation must also be full attention. Below outline discuss this issue.

(1)Measured media

Turbine Flowmeter measured by the liquid, is generally low viscosity of the (general should be less than 15 l0 -6 m 2 / s), low-corrosive liquids. Although the media has been used for various measurements of the turbine flowmeter, but the high-temperature, high-viscosity, strong corrosive media measurement need careful consideration and take corresponding measures. When the medium viscosity v larger than 15 l0 -6 m 2 / s, Flowmeter Instrument factor is the need for liquid calibration, or else they would have a greater error.

Steam - fluid flow, gas - solid two-phase, concentrated - solid two-phase turbine flow meter can not be measured.

(2)Piping installation requirements

Flowmeter installed in the flowmeter great impact on the accuracy of measurement

uneven distribution and velocity of flow in the secondary impact of the existence of turbine flowmeter accuracy of the important factors. Therefore, the turbine flowmeter, the lower reaches of a straight pipe - set requirements. For industrial measurement, the general requirements of the upper reaches 20 D, the lower reaches 5 D length of the straight. For the elimination of secondary movement, preferably in the upstream end of retrofitting Rectifier. If the upstream end to ensure that there are about 20 D of the straight, and to install rectifier, the flow meter can measure the accuracy of the calibration to achieve accuracy levels.

Turbine Flowmeter fluid cleanliness of a higher demand in the flow meter to be installed before the filter to ensure that the clean fluid. Filters can be funnel-shaped, and its cleanliness, can be measured by changes in the two ends of the differential.

To ensure that the liquid flow meter is through single-phase, that is, must not be allowed to enter the air or steam flow meter, in the upper reaches of the necessary flow meter should be installed for Xiaoqi. For easy gasification of the liquid in the downstream flow meter must be guaranteed to back pressure. The back pressure of the most desirable size of traffic flow under the double pressure sensor with the highest temperature measured liquid vapor pressure of 1.2 times.

(3)Signal transmission line

To ensure the instrument showed that the turbine sensor output pulse have sufficient sensitivity, it is necessary to improve the signal to noise ratio. To this end, the installation should be to prevent all kinds of electrical interference, or electromagnetic induction, electrostatic and capacitive coupling. Therefore, the allocation of signal transmission lines, we must pay attention to the following:

limit the maximum length signal lines. Signal for the maximum length, L = dV; one, V for a minimum flow sensor output voltage coil RMS, mV; d for the coefficient, m / mV, the value of its merits: V <1000mV time, d = 1 .0; 1000 mV 5000mV time, d = 2.0. Should, electrostatic and capacitive coupling. Therefore, the allocation of signal transmission lines, we must pay attention to the following:

signal transmission lines should be shielded cable, to prevent the sensors from the external noise. Require transmission lines in the show-meter shield grounding. Transmission lines can not be around strong electromagnetic equipment, and does not allow power lines between line layout.

(4)Maintenance operation

turbine flowmeter when the pipeline needs cleaning, we must open bypass, washing liquid can not flow meter.

pipeline system must be activated when a bypass, to prevent the sudden increase in velocity, excessive speed caused turbine damage.

Turbine Flowmeter bearings should be changed regularly, according to the general flow of small changes to observe its bearings wear.